Patent Application
20160154247
This application claims priority to Chinese Patent Application No. 201410715002.9, filed on Nov. 29, 2014, which is hereby incorporated by reference in its entirety.
The present invention relates to the field of optical communications technologies, and in particular, to a beam processing device, a beam attenuation and switching device, and an optical wavelength selective switch system.
For an optical transmission network, a reconfigurable optical add/drop multiplexer (Multiplexer, ROADM) technology may implement wavelength switching and dimension switching on an optical network node, and can flexibly expand a network capacity and reduce operating expense to meet a requirement for flexible scheduling on a service network.
Currently, in the ROADM, a beam processing device in an optical wavelength selective switch (WSS) system is generally used to perform polarization state splitting and adjustment on an input beam or an output beam. Currently, the beam processing device generally uses the following manner to process the input beam and the output beam: The input beam is shaped by using a micro lens array (MLA); after passing through a Wollaston prism, the shaped beam is split into two beams of linearly polarized lights whose polarization directions are perpendicular to each other. The two beams of linearly polarized lights are split along different directions with respective to an optical axis of the MLA, and then undergo phase compensation performed by a birefringent crystal; finally, after passing through a half-wave plate, one beam of linearly polarized lights rotates 90 degrees, to obtain two linearly polarized lights whose polarization directions are parallel to each other.
In order to implement splitting and adjustment of a beam polarization state, a solution of using the Wollaston prism, a phase compensation plate, and the half-wave plate for implementation is used in the foregoing. However, the Wollaston prism is generally obtained by using a technology such as grinding, where a production technology is complex, and a complex process is needed to assemble the foregoing parts, so that production of the beam processing device is also relatively complex, and production costs are also relatively high.
Embodiments of the present invention provide a beam processing device, a beam attenuation and switching device, and an optical wavelength selective switch system. The structure and the production technology of the beam processing device are simple.
According to a first aspect, a beam processing device is provided, including at least one quarter-wave plate array, where each quarter-wave plate array is corresponding to at least one polymer polarization grating, and the polymer polarization grating and the quarter-wave plate array are successively arranged on an optical transmission path, where:
the polymer polarization grating splits a beam that is incident on a surface of the polymer polarization grating into a left-handed circularly polarized light and a right-handed circularly polarized light; and
the quarter-wave plate array includes at least two quarter-wave plates whose slow axes are in different directions, and adjusts, to linearly polarized lights that have a same polarization direction, the left-handed circularly polarized light and the right-handed circularly polarized light that are obtained after the polymer polarization grating performs the splitting.
With reference to the first aspect, in a first implementation manner, each quarter-wave plate array is corresponding to one polymer polarization grating; and
the one polymer polarization grating corresponding to each quarter-wave plate array is configured to split a beam that is incident on a surface of the polymer polarization grating into a left-handed circularly polarized light and a right-handed circularly polarized light that have different transmission angles.
With reference to the first aspect, in a second implementation manner, each quarter-wave plate array is corresponding to two polymer polarization gratings; and
the two polymer polarization gratings corresponding to each quarter-wave plate array are configured to split a beam that is incident on a surface of the polymer polarization gratings into a left-handed circularly polarized light and a right-handed circularly polarized light that have a same transmission angle.
According to a second aspect, a beam attenuation and switching device is provided, including a switchable polarization grating and an optical path angle adjustment device, where the switchable polarization grating and the optical path angle adjustment device are successively arranged on an optical transmission path, where:
the switchable polarization grating is configured to: when a first voltage is applied, after diffracting an incident beam, change a polarization state and a transmission angle that are of the incident beam; when a second voltage is applied, after diffracting an incident beam, skip changing a polarization state and a transmission angle that are of the incident beam; or when different voltages are applied, diffract an incident beam, so as to change the incident beam to another transmission angle different from an original transmission angle, and attenuate a beam in a direction of the original transmission angle; and
the optical path angle adjustment device is configured to adjust, to a different transmission angle, a beam that is incident on the optical path angle adjustment device after passing through the switchable polarization grating, and then output the beam.
With reference to the second aspect, in a first implementation manner, the optical path angle adjustment device is a liquid crystal on silicon or micro-electro-mechanical systems.
According to a third aspect, a beam attenuation and switching device is provided, including a first half-wave liquid crystal plate, a first quarter-wave plate, a polymer polarization grating, and an optical path angle adjustment device that are successively arranged on an optical transmission path, where:
the first half-wave liquid crystal plate is configured to: at different voltages, change a polarization direction of a linearly polarized light that is incident on a surface of the first half-wave liquid crystal plate;
the first quarter-wave plate is configured to adjust, to a left-handed circularly polarized light or a right-handed circularly polarized light, a linearly polarized light that is obtained after the first half-wave liquid crystal plate performs processing;
the polymer polarization grating is configured to split, into lights that have different transmission angles, the left-handed circularly polarized light or the right-handed circularly polarized light that is obtained after the first quarter-wave plate performs processing; and
the optical path angle adjustment device is configured to adjust, to different transmission angles, the lights that have different transmission angles, are obtained after the polymer polarization grating performs the splitting, and are incident on a surface of the optical path angle adjustment device, and then reflect adjusted lights for outputting, where after successively passing through the polymer polarization grating, the first quarter-wave plate, and the first half-wave liquid crystal plate, the reflected lights become linearly polarized lights that have a same polarization direction.
With reference to the third aspect, in a first implementation manner, the optical path angle adjustment device is micro-electro-mechanical systems.
With reference to the third aspect, in a second implementation manner, the optical path angle adjustment device is a liquid crystal on silicon, the beam attenuation and switching device further includes a second quarter-wave plate and a second half-wave liquid crystal plate that are successively arranged on the optical transmission path, the second quarter-wave plate and the second half-wave liquid crystal plate are located between the liquid crystal on silicon and the polymer polarization grating, the second quarter-wave plate is adjacent to the polymer polarization grating, and the second half-wave liquid crystal plate is adjacent to the liquid crystal on silicon, where:
the second quarter-wave plate is configured to adjust, to linearly polarized lights, the left-handed circularly polarized lights or the right-handed circularly polarized lights that have different transmission angles and are obtained after the polymer polarization grating performs the splitting;
the second half-wave liquid crystal plate is configured to adjust, to linearly polarized lights that have a same polarization direction, the linearly polarized lights that are obtained after the second quarter-wave plate performs processing, and enable the polarization direction of the linearly polarized lights that are incident on a surface of the liquid crystal on silicon to be consistent with a direction of an optical axis of the liquid crystal on silicon; and
the liquid crystal on silicon is configured to adjust, to different transmission angles, the linearly polarized lights that are adjusted by the second half-wave liquid crystal plate and then are incident on the surface of the liquid crystal on silicon, and reflect adjusted lights for outputting, where after successively passing through the second half-wave liquid crystal plate, the second quarter-wave plate, the polymer polarization grating, the first quarter-wave plate, and the first half-wave liquid crystal plate, the reflected linearly polarized lights become linearly polarized lights that have a same polarization direction.
According to a fourth aspect, an optical wavelength selective switch system is provided, including an optical fiber array, a beam processing subsystem, an optical path transmission subsystem, and an optical path switching subsystem, where
the optical fiber array is configured to send at least one input beam to the beam processing subsystem and receive at least one output beam output by the beam processing subsystem;
the beam processing subsystem includes the beam processing device involved in the first aspect or either implementation manner of the first aspect, and performs polarization state splitting and adjustment on the input beam or the output beam by using the beam processing device, to obtain linearly polarized lights that have a same polarization direction;
the optical path transmission subsystem is configured to diffract and split, according to different angles, the linearly polarized lights that have the same polarization direction and are obtained after the beam processing device in the beam processing subsystem performs processing, and then transmit the linearly polarized lights to the optical path switching subsystem; and
the optical path switching subsystem includes the beam attenuation and switching device involved in the second aspect, the implementation manner of the second aspect, the third aspect, or either implementation manner of the third aspect, and is configured to change an angle of a beam transmitted by the optical path transmission subsystem, so as to implement attenuation and optical path switching functions.
With reference to the fourth aspect, in a first implementation manner, the optical path transmission subsystem includes a first cylindrical lens, a transmission grating, and a second cylindrical lens, where
an optical axis of the second cylindrical lens and an optical axis of the first cylindrical lens are perpendicular to each other;
the transmission grating is located between the first cylindrical lens and the second cylindrical lens, and a distance between the transmission grating and the second cylindrical lens is less than a distance between the transmission grating and the first cylindrical lens;
the beam processing device in the beam processing subsystem and the beam attenuation and switching device in the optical path switching subsystem are located at a location of focuses of the first cylindrical lens and the second cylindrical lens;
the first cylindrical lens is configured to reflect the linearly polarized lights that have the same polarization direction and are obtained after the beam processing device in the beam processing subsystem performs processing, to parallel linearly polarized lights in a plane that is perpendicular to the optical axis of the first cylindrical lens;
the transmission grating is configured to perform, according to different angles, first diffraction on the parallel linearly polarized lights obtained after the reflection performed by the first cylindrical lens, and perform, according to different angles, second diffraction on a beam reflected by the second cylindrical lens; and
the second cylindrical lens is configured to reflect beams obtained after the transmission grating performs the first diffraction, to parallel linearly polarized lights in a plane that is perpendicular to the optical axis of the second cylindrical lens, and enable the reflected parallel linearly polarized lights to be incident on the transmission grating.
In the beam processing device, the beam attenuation and switching device, and the optical wavelength selective switch system provided in the embodiments of the present invention, the beam processing device includes a polymer polarization grating and a quarter-wave plate array, and the polymer polarization grating splits an input beam into a left-handed circularly polarized light and a right-handed circularly polarized light. The quarter-wave plate array adjusts, to linearly polarized lights that have a same polarization direction, the left-handed circularly polarized light and the right-handed circularly polarized light that are obtained after the polymer polarization grating performs the splitting. Therefore, in the embodiments of the present invention, splitting and adjustment of a beam polarization state may be implemented by using the polymer polarization grating and the quarter-wave plate array, where a structure is simpler and assembly is also simpler compared with a traditional beam processing device that is formed by using a Wollaston prism, a phase compensation plate, and a half-wave plate. In addition, production technologies of the polymer polarization grating and the quarter-wave plate are also simpler compared with a production technology of the Wollaston prism; therefore, the embodiments of the present invention may simplify the production technology of the beam processing device.
The following clearly describes the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are merely some but not all of the embodiments of the present invention. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.
The polymer polarization grating splits a beam that is incident on a surface of the polymer polarization grating into a left-handed circularly polarized light and a right-handed circularly polarized light; the quarter-wave plate array includes at least two quarter-wave plates whose slow axes are in different directions, and adjusts, to linearly polarized lights that have a same polarization direction, the left-handed circularly polarized light and the right-handed circularly polarized light that are obtained after the polymer polarization grating performs the splitting.
In the following, an embodiment of the present invention uses an example in which a beam processing device performs processing on a beam that is shaped by a micro lens array for description, as shown in
In this embodiment of the present invention, a beam processing device 102 is adjacent to a micro lens array 101. The beam processing device 102 includes a polymer polarization grating 1021 (PPG) and a quarter-wave plate array 1022 (QWPA). The micro lens array 101, the polymer polarization grating 1021, and the quarter-wave plate array 1022 are successively arranged on an optical transmission path.
In this embodiment of the present invention, the PPG 1021 included in the beam processing device 102 may be obtained by production in a manner of interference light exposure to a polymer liquid crystal.
First, a layer of an optical stereoregular polymer material 202 is formed on a glass substrate 201 in a manner such as painting, as shown in
Second, a light field that is obtained by mutual interference of a left-handed ultraviolet light and a right-handed ultraviolet light 203 is used for light exposure to the optical stereoregular polymer material 202, as shown in
Third, a layer of a liquid crystal material 204 that has a polymerization characteristic is coated on the optical stereoregular polymer material 202 that has been exposed in
Finally, an uniform ultraviolet light 205 is used to shine on the liquid crystal material 204 that has the polymerization characteristic, thereby solidifying a liquid crystal molecule arrangement in the liquid crystal material 204, as shown in
In this embodiment of the present invention, the QWPA 1022 included in the beam processing device 102 may also be obtained by production in the manner of interference light exposure to a polymer liquid crystal. A specific production technology is similar to a process of producing the PPG 1021. However, in a process of light exposure to the optical stereoregular polymer material 202, a linearly polarized ultraviolet light is used, but not the left-handed ultraviolet light and the right-handed ultraviolet light.
In this embodiment of the present invention, the PPG 1021 has functions of changing a polarization state and a transmission angle that are of a right-handed circularly polarized light and a left-handed circularly polarized light, as shown in
In this embodiment of the present invention, the QWPA 1022 is equivalent to multiple quarter-wave plates that are of a same width, in different directions of slow axes, and successively arranged. The quarter-wave plates may be arranged side by side or arranged up and down. As shown in
In this embodiment of the present invention, the PPG 1021 is adjacent to the MLA 101 and configured to split a beam that is shaped by the MLA 101 into a left-handed circularly polarized light and a right-handed circularly polarized light. Shaping a beam refers to changing a size of a light spot of the beam. The QWPA 1022 is located on an optical transmission path that is adjacent to the PPG 1021, and adjusts, to linearly polarized lights that have a same polarization direction, the left-handed circularly polarized light and the right-handed circularly polarized light that are obtained after the PPG 1021 performs the splitting.
In the beam processing device provided in this embodiment of the present invention, an input beam is split into a left-handed circularly polarized light and a right-handed circularly polarized light by using a PPG 1021, and the left-handed circularly polarized light and the right-handed circularly polarized light that are obtained after the PPG 1021 performs the splitting are adjusted by using a QWPA 1022 to linearly polarized lights that have a same polarization direction. Therefore, in this embodiment of the present invention, the beam processing device may implement splitting and adjustment of a beam polarization state by using the PPG 1021 and the QWPA 1022, where a structure is simpler and further assembly is also simpler compared with a traditional beam processing device that is formed by using a Wollaston prism, a phase compensation plate, and a half-wave plate. In addition, in this embodiment of the present invention, the PPG 1021 and the QWPA 1022 may be obtained by production in a manner of light exposure to a polymer liquid crystal, and a used production technology is also simpler compared with a production technology of the Wollaston prism; therefore, this embodiment of the present invention may simplify a production technology of the beam processing device.
Further, in this embodiment of the present invention, production of the PPG 1021 and the QWPA 1022 may be implemented on a large glass substrate, and then a device of a required size is obtained by using a cutting technology. For example, a size of a device that is used is 2*5 square millimeters; then, a two-inch square glass substrate may produce 250 devices; therefore, a cost of a single device is quite low.
The beam processing device provided in this embodiment of the present invention may be applied to an optical system in which a beam polarization state needs to be adjusted, where the optical system may be, for example, an optical wavelength selective switch system. The beam processing device provided in this embodiment of the present invention may flexibly adjust a combination manner of the PPG 1021 and the QWPA 1022 that are in the beam processing device 102, so as to be applicable to different optical systems.
In this embodiment of the present invention, in order to implement that an incident beam is split and adjusted into two linearly polarized lights that have different transmission angles and a same polarization direction, one PPG 1021 and a group of QWPAs 1022 may be used in the beam processing device 102. After an input beam passes through the PPG 1021, the input beam may be split into a left-handed circularly polarized light and a right-handed circularly polarized light that have different transmission angles; then, after the left-handed circularly polarized light and the right-handed circularly polarized light pass through the QWPA 1022, linearly polarized lights that have a same polarization direction may be obtained. A plane in which a beam polarization state is split is perpendicular to a plane in which input optical fibers and output optical fibers reside. For a specific structure, reference may be made to
In this embodiment of the present invention, directions in which optical fibers are arranged in the beam processing device may also be parallel with the plane in which the beam polarization state is split, as shown in
In this embodiment of the present invention, in order to implement that an incident beam is split and adjusted into two linearly polarized lights that have a same transmission angle and a same polarization direction, two PPGs 1021 and a group of QWPAs 1022 may be used in each beam processing device 102. After an input beam passes through the first PPG 1021, the input beam may be split into a left-handed circularly polarized light and a right-handed circularly polarized light that have different transmission angles. After passing through the first PPG 1021, the left-handed circularly polarized light and the right-handed circularly polarized light pass through the second PPG 1021, and a left-handed circularly polarized light and a right-handed circularly polarized light that shine in parallel with each other may be obtained. The right-handed circularly polarized light and left-handed circularly polarized light that pass through the second PPG 1021 and shine in parallel to each other pass through the QWPA 1022, so that linearly polarized lights that have a same polarization direction may be obtained, as shown in
In
Based on the beam processing device provided in the foregoing embodiment of the present invention, an embodiment of the present invention further provides an optical wavelength selective switch system 900. The optical wavelength selective switch system 900 includes a beam processing subsystem 901, an optical path transmission subsystem 902, and an optical path switching subsystem 903, and certainly the optical wavelength selective switch system 900 further includes an optical fiber array 904, as shown in
In
A beam that is attenuated and switched by the optical path switching subsystem 903 is separately processed by the optical path transmission subsystem 902 and the beam processing subsystem 901 according to a reversible process of an optical path. A beam that is returned and coupled is output to the optical fiber array that is used as an output port.
In the optical wavelength selective switch system provided in this embodiment of the present invention, the beam processing subsystem 901 is configured to perform processing on an input beam and an output beam. The optical fiber array 904 in the optical wavelength selective switch system is used as an input port and an output port to send at least one input beam to the beam processing subsystem 901 and receive at least one output beam output by the beam processing subsystem 901. The input beam is an incident beam that is transmitted through an input port of the optical fiber array to the optical system, and the output beam is a beam that is returned and coupled by the optical system and then output to an output port. In this embodiment of the present invention, for a process in which the beam processing subsystem 901 performs polarization state splitting and adjustment on the input beam to obtain linearly polarized lights that have a same polarization direction, reference may be made to the processing process shown in
Second, in this embodiment of the present invention, the optical path transmission subsystem 902 may use a transmission grating, a first cylindrical lens, and a second cylindrical lens to diffract and split, according to different angles, the linearly polarized lights that have the same polarization direction and are obtained after the beam processing device in the beam processing subsystem 901 performs processing. A cylindrical lens may be considered as a non-axisymmetric special aspheric lens. The cylindrical lens may provide a scattering or focusing function in a plane that is perpendicular to an optical axis of the cylindrical lens, and the cylindrical lens in a plane that is parallel with the optical axis of the cylindrical lens is equivalent to a plane. In this embodiment of the present invention, that the transmission grating, the first cylindrical lens, and the second cylindrical lens diffract and split, according to different angles, the linearly polarized lights that have the same polarization direction may use the following manner: An optical axis of the first cylindrical lens is parallel with a direction in which the optical fiber array is arranged, and an optical axis of the second cylindrical lens is perpendicular to the optical axis of the first cylindrical lens. The transmission grating is located between the first cylindrical lens and the second cylindrical lens, and a distance between the transmission grating and the second cylindrical lens is less than a distance between the transmission grating and the first cylindrical lens; the first cylindrical lens is configured to reflect the linearly polarized lights that have the same polarization direction and are obtained after the beam processing device in the beam processing subsystem 901 performs processing, to parallel linearly polarized lights in a plane that is perpendicular to the optical axis of the first cylindrical lens; the transmission grating is configured to perform, according to different angles, first diffraction on the parallel linearly polarized lights that are obtained after the reflection performed by the first cylindrical lens and are in the plane that is perpendicular to the optical axis of the first cylindrical lens, and perform, according to different angles, second diffraction on a beam reflected by the second cylindrical lens; and the second cylindrical lens is configured to reflect a beam obtained after the transmission grating performs the first diffraction, to parallel linearly polarized lights in a plane that is perpendicular to the optical axis of the second cylindrical lens, and enable the reflected parallel linearly polarized lights to be incident on the transmission grating. In this embodiment of the present invention, the transmission grating may diffract and split, according to different angles, beams that are of wavelengths and are incident on a surface of the transmission grating. In addition to changing a light spot, the cylindrical lenses may further reflect, to the transmission grating, a beam diffracted by the transmission grating, to enable the transmission grating to perform the second diffraction on the beam, so that the beam passes through the transmission grating twice; further, an angle at which the beam is split is larger; and further, locations of devices that are in the optical system and used to transmit the beam may be more compact, reducing an overall size of the optical system, and reducing power consumption.
In this embodiment of the present invention, a linearly polarized light is used as an example for description. In a plane that is perpendicular to an optical axis of a first cylindrical lens, as shown in
In this embodiment of the present invention, the optical path transmission subsystem 902 may use the transmission grating and the cylindrical lenses, which may enable a beam to pass through the transmission grating twice, and further enable a split angle at which the beam is diffracted to double. Two adjacent optical signals that have a gap of 50 GHz are used as an example, and it is assumed that distances by which the two optical signals are split in the optical path switching subsystem are the same. Because a split distance in the optical path switching subsystem is a product of a focal length and a split angle, if a split angle increases twice, a focal length may decrease by a half, which means that a focal length of the entire system may decrease by a half. Because the focal length of the entire system becomes shorter, a distance between the optical fiber array and the cylindrical lens also becomes shorter. In this case, the system becomes more compact, and a smaller beam waist may be used for transmission, thereby further obtaining 3 dB spectrum bandwidth.
It should be noted that
An optical path angle adjustment device may generally be used in the optical path switching subsystem 903. A beam is attenuated by using the optical path angle adjustment device, and the beam is routed to a set output port and then coupled for outputting. The optical path angle adjustment device may be, for example, a liquid crystal on silicon (LCOS), micro-electro-mechanical systems (MEMS), or the like. The LCOS adjusts an output angle by generating phase gratings of different periods, and the MEMS adjust an output angle by directly adjusting angles of different micro lenses.
Currently, in a process in which only the optical path angle adjustment device performs attenuation and switching on a beam, random crosstalk of the beam may be made to another transmission path, which causes instantaneous crosstalk. In this embodiment of the present invention, a switchable polarization grating (SPG) may be added in front of the optical path angle adjustment device, so as to conveniently implement attenuation of an optical path and overcome a problem of instantaneous crosstalk.
The SPG in this embodiment of the present invention may be produced by using the following production process:
First, an electrode layer 1102 and a light sensitive polymer material 1103 are separately formed on two glass substrates 1101, the two glass substrates on which the electrode layer 1102 and the light sensitive polymer material 1103 are formed are packaged together, and a gap between the two glass substrates is reserved for injection of liquid crystal, as shown in
Second, an optical field that is obtained by mutual interference of a left-handed ultraviolet light and a right-handed ultraviolet light 1104 is used for light exposure to the light sensitive polymer material 1103 and solidifying a molecule arrangement in the light sensitive polymer material 1103, and then liquid crystal 1105 is injected into the gap, so that liquid crystal molecules are arranged according to a hologram of the polymer material, as shown in
In this embodiment of the present invention, the SPG that is produced by using the foregoing method may have characteristics shown in
In this embodiment of the present invention, the SPG is added in front of the optical path angle adjustment device in the optical path switching subsystem 903, beams that pass through the SPG are transmitted in different directions according to values of voltages applied to the SPG and different polarization states of the input beams. When a high voltage is applied to the SPG, an input light may be transmitted in an original direction; when a low voltage is applied to the SPG, a left-handed circularly polarized light or a right-handed circularly polarized light becomes a right-handed circularly polarized light or a left-handed circularly polarized light and is diffracted to another direction at a relatively large angle; a light reflected by the optical path angle adjustment device cannot be coupled to an output port of the optical fiber array because of a too large angle, and therefore is completely lost, as shown in
In a specific implementation process of this embodiment of the present invention, a beam that is transmitted by the optical path transmission subsystem to the optical path switching subsystem is a linearly polarized light; therefore, two QWPs and one SPG are combined together to implement the foregoing beam attenuation function in this embodiment of the present invention, as shown in
In this embodiment of the present invention, the optical path angle adjustment device 1303 may be an LCOS or MEMS. If the optical path angle adjustment device 1303 is the LCOS, and the LCOS is applied to this embodiment of the present invention, an optical path switching process may be implemented without using a complex control algorithm for the LCOS. If the optical path angle adjustment device is the MEMS, and the MEMS are applied to this embodiment of the present invention, a problem of instantaneous crosstalk in the optical path switching process may be prevented by using one-dimensional MEMS without using two-dimensional MEMS, thereby reducing MEMS processing difficulty and reducing a cost.
In this embodiment of the present invention, a beam outgoing angle of the optical path switching subsystem 903 may also be increased, so as to achieve coupling to more output ports of the optical fiber array, and also to improve diffraction efficiency of the optical path switching subsystem 903. In this embodiment of the present invention, a PPG, a QWP, a half-wave liquid crystal plate, and an optical path angle adjustment device that are successively arranged on an optical transmission path may be used in the optical path switching subsystem 903. The half-wave liquid crystal plate is configured to: at different voltages, change a polarization direction of a linearly polarized light that is incident on a surface of the half-wave liquid crystal plate; the QWP is configured to adjust, to a left-handed circularly polarized light or a right-handed circularly polarized light, a linearly polarized light that is obtained after the half-wave liquid crystal plate performs processing; the PPG is configured to split, into lights that have different transmission angles, the left-handed circularly polarized light or the right-handed circularly polarized light that is obtained after the quarter-wave plate performs processing, and change polarization states; and the optical path angle adjustment device is configured to adjust, to different transmission angles, the lights that are incident on a surface of the optical path angle adjustment device, and then reflect adjusted lights for outputting, where after successively passing through the PPG, the QWP, and the half-wave liquid crystal plate, the reflected lights become linearly polarized lights that have a same polarization direction, and the linearly polarized lights are routed to the output port of the optical fiber array.
In this embodiment of the present invention, the optical path angle adjustment device may be an LCOS or MEMS.
If the optical path angle adjustment device is the LCOS, in this embodiment of the present invention, a second QWP and a second half-wave liquid crystal plate that are successively arranged further need to be disposed between the LCOS and the PPG, so as to meet a requirement of the LCOS for the linearly polarized lights. The second QWP is adjacent to the PPG, and the second half-wave liquid crystal plate is adjacent to the LCOS. The second QWP is configured to adjust, to linearly polarized lights, the left-handed circularly polarized lights or the right-handed circularly polarized lights that have different transmission angles and are obtained after the PPG performs the splitting; the second half-wave liquid crystal plate is configured to adjust, to linearly polarized lights that have a same polarization direction, the linearly polarized lights that are obtained after the second QWP performs processing, and enable the polarization direction of the linearly polarized lights that are incident on the LCOS to be consistent with a direction of an optical axis of the LCOS; the LCOS is configured to adjust, to different transmission angles, the linearly polarized lights that are adjusted by the second half-wave liquid crystal plate and then are incident on a surface of the LCOS, and reflect adjusted lights for outputting, where after successively passing through the second half-wave liquid crystal plate, the second QWP, the PPG, the QWP, and the half-wave liquid crystal plate, the reflected linearly polarized lights become linearly polarized lights that have a same polarization direction. As shown in
If the optical path angle adjustment device is the MEMS, there is no special requirement for a beam polarization state; then, a second QWP and a second half-wave liquid crystal plate do not need to be disposed.
As shown in
It may be learned from
In this embodiment of the present invention, the optical path angle adjustment device may be an LCOS or MEMS. If the optical path angle adjustment device is the LCOS, the LCOS is applied to this embodiment of the present invention, and it is assumed that a quantity of output ports keeps unchanged, a diffraction angle of the LCOS may decrease by a half, so that a phase grating period of the LCOS doubles; therefore, a variation of a phase of a grating may be smoother, and diffraction efficiency may be improved. If the optical path angle adjustment device is the MEMS, the MEMS are applied to this embodiment of the present invention, and it is assumed that a quantity of output ports keeps unchanged, a rotation angle of the MEMS may decreases by a half, thereby reducing a drive voltage of the MEMS, simplifying design of a drive circuit, and reducing a cost.
In the optical wavelength selective switch system 900 provided in this embodiment of the present invention, compared with a Wollaston prism, a phase compensation plate, and a half-wave plate that are traditionally used, a PPG and a QWPA are used in a beam processing subsystem, which can implement splitting and adjustment of a beam polarization state more easily, and production technologies of the PPG and the QWPA are simple, so that assembly and production of a beam processing device in the beam processing subsystem are also simpler.
In the optical wavelength selective switch system 900, a transmission grating and cylindrical lenses are used in a beam transmission subsystem, so that a beam may pass through the transmission grating twice, which can reduce a focal length of the optical wavelength selective switch system. Because the focal length of the entire system becomes shorter, the optical wavelength selective switch system is more compact. In addition, a smaller beam waist may be used for transmission, thereby further obtaining 3 dB spectrum bandwidth. In the optical wavelength selective switch system 900, an SPG is used in a beam switching subsystem, which may implement attenuation more conveniently, and can solve a problem of instantaneous crosstalk. In the optical wavelength selective switch system 900, a PPG, a QWP, and a half-wave liquid crystal plate are used in the optical path switching subsystem, which increase an outgoing angle of a beam routed by the optical path switching subsystem 903, so as to achieve coupling to more output ports of an optical fiber array, and improve diffraction efficiency.
An embodiment of the present invention further provides a beam attenuation and switching device, including an SPG and an optical path angle adjustment device that are successively arranged on an optical transmission path.
The SPG is configured to: when a first voltage is applied, after diffracting an incident beam, change a polarization state and a transmission angle that are of the beam; when a second voltage is applied, skip changing a polarization state and a transmission angle that are of a beam; or when different voltages are applied, change energy of a beam diffracted to another transmission angle different from an original transmission angle, and attenuate a beam in a direction of the original transmission angle. For example, in this embodiment of the present invention, when a zero voltage or a low voltage is applied, after an incident beam is diffracted, a polarization state and a transmission angle (level ±1) that are of the beam are changed; when a high voltage is applied, a transmission angle (level 0) or a polarization direction that are of a beam is not changed; when different voltages are applied, a beam may be controlled to be diffracted to level ±1, thereby implementing different attenuation of a level-0 beam.
The optical path angle adjustment device is configured to adjust, to a different transmission angle, a beam that is incident on the optical path angle adjustment device after passing through the SPG, and then output the beam.
The beam attenuation and switching device provided in this embodiment of the present invention includes an optical path angle adjustment device and an SPG. The SPG is used in front of the optical path angle adjustment device. The SPG may be used to implement attenuation; the optical path angle adjustment device is merely used for optical path switching, which simplifies a control process of optical path switching. Further, in this embodiment of the present invention, in an optical path switching process, attenuation of the SPG is first adjusted to a maximum value, and then optical path switching is performed by using the optical path angle adjustment device. After the optical path angle adjustment device is steady, the attenuation of the SPG is adjusted to a required value, which may prevent instantaneous crosstalk in the optical path switching process.
In this embodiment of the present invention, the optical path angle adjustment device may be an LCOS or MEMS. If the optical path angle adjustment device is the LCOS, and the LCOS is applied to this embodiment of the present invention, an optical path switching process may be implemented without using a complex control algorithm for the LCOS. If the optical path angle adjustment device is the MEMS, and the MEMS are applied to this embodiment of the present invention, a problem of instantaneous crosstalk in the optical path switching process may be prevented by using one-dimensional MEMS without using two-dimensional MEMS, thereby reducing MEMS processing difficulty and reducing a cost.
The beam attenuation and switching device provided in this embodiment of the present invention may be applied to various optical systems, for example, an optical wavelength selective switch system. For description, not detailed enough, about the beam attenuation and switching device provided in this embodiment of the present invention, reference may be made to
An embodiment of the present invention further provides a beam attenuation and switching device, including a first half-wave liquid crystal plate, a first QWP, a PPG, and an optical path angle adjustment device that are successively arranged on an optical transmission path, where
the first half-wave liquid crystal plate is configured to: at different voltages, change a polarization direction of a linearly polarized light that is incident on a surface of the first half-wave liquid crystal plate;
the first QWP is configured to adjust, to a left-handed circularly polarized light or a right-handed circularly polarized light, a linearly polarized light that is obtained after the first half-wave liquid crystal plate performs processing;
the PPG is configured to split, into lights that have different transmission angles, the left-handed circularly polarized light or the right-handed circularly polarized light that is obtained after the first QWP performs processing; and
the optical path angle adjustment device is configured to adjust, to different transmission angles, the linearly polarized lights that are incident on a surface of the optical path angle adjustment device, and then reflect adjusted lights for outputting, where after successively passing through the PPG, the first QWP, and the first half-wave liquid crystal plate, the reflected linearly polarized lights become linearly polarized lights that have a same polarization direction.
In this embodiment of the present invention, the optical path angle adjustment device may be an MEMS or LCOS.
In this embodiment of the present invention, if the optical path angle adjustment device is the LCOS, the beam attenuation and switching device further includes a second QWP and a second half-wave liquid crystal plate that are successively arranged on the optical transmission path, the second QWP and the second half-wave liquid crystal plate are located between the LCOS and the PPG, the second QWP is adjacent to the PPG, and the second half-wave liquid crystal plate is adjacent to the LCOS, where
the second QWP is configured to adjust, to linearly polarized lights, the left-handed circularly polarized lights or the right-handed circularly polarized lights that have different transmission angles and are obtained after the PPG performs the splitting;
the second half-wave liquid crystal plate is configured to adjust, to linearly polarized lights that have a same polarization direction, the linearly polarized lights that are obtained after the second QWP performs processing, and enable the polarization direction of the linearly polarized lights that are incident on a surface of the LCOS to be consistent with a direction of an optical axis of the LCOS; and
the LCOS is configured to adjust, to different transmission angles, the linearly polarized lights that are adjusted by the second half-wave liquid crystal plate and then are incident on the surface of the LCOS, and reflect adjusted lights for outputting, where after successively passing through the second half-wave liquid crystal plate, the second QWP, the PPG, the first QWP, and the first half-wave liquid crystal plate, the reflected linearly polarized lights become linearly polarized lights that have a same polarization direction.
In the beam attenuation and switching device provided in this embodiment of the present invention, a half-wave liquid crystal plate, a QWP, and a PPG are used in front of an optical path angle adjustment device, which may enable an outgoing angle of an optical path switching subsystem to double, which achieves coupling to more output ports.
In this embodiment of the present invention, the optical path angle adjustment device may be an LCOS or MEMS. If the optical path angle adjustment device is the LCOS, the LCOS is applied to this embodiment of the present invention, and it is assumed that a quantity of output ports keeps unchanged, a diffraction angle of the LCOS may decrease by a half, so that a phase grating period of the LCOS doubles; therefore, a variation of a phase of a grating may be smoother, and diffraction efficiency may be improved. If the optical path angle adjustment device is the MEMS, the MEMS are applied to this embodiment of the present invention, and it is assumed that a quantity of output ports keeps unchanged, a rotation angle of the MEMS may decrease by a half, thereby reducing a drive voltage of the MEMS, simplifying design of a drive circuit, and reducing a cost.
The beam attenuation and switching device provided in this embodiment of the present invention may be applied to various optical systems, for example, an optical wavelength selective switch system. For description, not detailed enough, about the beam attenuation and switching device provided in this embodiment of the present invention, reference may be made to
It should be noted that, an incident beam, a beam that is processed by a related device, or the like that is described in the foregoing and shown in the accompanying drawings in the embodiments of the present invention uses one beam as an example for description, which is merely for ease of illustration and description. The embodiments of the present invention set no limitation on a quantity of beams. A quantity of the beams that are involved in the embodiments of the present invention is at least one, and a quantity of beams that involve same or different transmission angles, or same or different polarization directions is at least two.
Obviously, a person skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. The present invention is intended to cover these modifications and variations provided that they fall within the scope of protection defined by the following claims and their equivalent technologies.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201410715002.9 | Nov 2014 | CN | national |
