Embodiments of the present invention relate to the field of optical communications technologies, and in particular, to an optical switch chip, an optical switch driving module, and an optical switch driving method.
An optical communications network mainly includes three parts: a transport network, a switching network, and an access network. An electrical switch in the switching network is faced with technical limits of a switching speed, energy consumption, and the like, and cannot meet a requirement of a large switching throughput when high bandwidth is required. As an optical signal switching technology of low energy consumption and a large throughput, an all-optical switching technology is to replace an electrical switching technology and become a main technology in a future switching network.
A core component for implementing the all-optical switching technology is an optical switch matrix. The optical switch matrix is formed by a particular quantity of optical switch units according to a regular topology structure. A switching scale in which both a quantity of input ports of the optical switch matrix and a quantity of output ports of the optical switch matrix are N is called an N×N switching scale. In the N×N switching scale, a total quantity of optical switch units that the optical switch matrix requires may be N2. Each optical switch unit requires one or two phase shifters. The phase shifter can enable, merely in a specific direct current voltage or current, the optical switch unit to be in a direct-connected state or a cross-connected state. Therefore, each optical switch unit needs to be configured with and driven by an independent digital-to-analog conversion (DAC) driving unit, and one optical switch matrix generally needs to be driven by many DAC driving units.
For example, an optical switch module includes a main chip, a phase shifter, a DAC driving unit, and the like. The main chip includes an optical switch matrix, and the main chip is surrounded by a circle of electrodes, where each electrode is configured to connect to a corresponding phase shifter and DAC driving unit, and the DAC driving unit can drive a corresponding optical switch unit.
However, as a scale of the optical switch matrix increases, when optical switch units reach a particular quantity, even if the main chip is fully surrounded by electrodes, a quantity of electrodes of the main chip still cannot match the quantity of optical switch units, and consequently some optical switch units cannot be driven normally.
Embodiments of the present invention provide an optical switch driving module and an optical switch driving method that can reduce a quantity of used electrodes.
A first aspect of the present invention provides an optical switch driving module, including an optical switch chip and a multi-frequency driving signal source that is connected to the optical switch chip; the optical switch chip includes an optical switch matrix, and optical switch units of the optical switch matrix are divided into N groups, where N is a natural number greater than or equal to 1; each group of optical switch units shares a pair of electrodes, each pair of electrodes is configured to connect to a multi-frequency driving signal source, and each optical switch unit is connected to a band-pass filter and connects to the multi-frequency driving signal source by using the band-pass filter; pass bands of M band-pass filters that are connected to M optical switch units in a same group are different, where M is a natural number greater than or equal to 2; and the multi-frequency driving signal source outputs multiple driving signals of different frequencies that are respectively corresponding to the pass bands of the M band-pass filters, so as to drive the group of optical switch units.
A second aspect of the present invention provides an optical switch chip that includes multiple optical switch units, where the multiple optical switch units are divided into N groups, and N is a natural number greater than or equal to 1; each group of optical switch units shares a pair of electrodes, each pair of electrodes is configured to connect to a multi-frequency driving signal source, and each optical switch unit is connected to a band-pass filter and connects to the multi-frequency driving signal source by using the band-pass filter; and pass bands of M band-pass filters that are connected to M optical switch units in a same group are different, where M is a natural number greater than or equal to 2.
A third aspect of the present invention provides an optical switch driving method, including: dividing optical switch units of an optical switch matrix into N groups, where N is a natural number greater than or equal to 1; each group of optical switch units shares a pair of electrodes, each pair of electrodes is configured to connect to a multi-frequency driving signal source, and each optical switch unit is connected to a band-pass filter and connects to the multi-frequency driving signal source by using the band-pass filter; and pass bands of M band-pass filters that are connected to M optical switch units in a same group are different, where M is a natural number greater than or equal to 2; and outputting, by the multi-frequency driving signal source, multiple driving signals of different frequencies that are corresponding to the pass bands of the M band-pass filters, so as to drive the group of optical switch units.
To describe the technical solutions in the embodiments of the present invention more clearly, the following briefly describes the accompanying drawings required for describing the embodiments. Apparently, the accompanying drawings in the following description show merely some embodiments of the present invention, and a person of ordinary skill in the art may still derive other drawings from these accompanying drawings without creative efforts.
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.
Referring to
Referring to
The filter 120 is a band-pass filter, and allows only a signal of a specific frequency to drive a corresponding phase shifter. Pass bands of N band-pass filters that are connected to N optical switch units 110 in a same group are different. A multi-frequency driving signal source 200 connected to each group of optical switch units can provide driving signals of multiple frequencies, and the frequencies of the driving signals respectively correspond to the pass bands of the band-pass filters. Amplitude of a driving signal of each frequency can be independently adjusted, and different optical switch units can be controlled by adjusting amplitude or power values of different frequency components.
Phase shifters of optical switch units in a same group require different driving signal frequencies. Phase shifters of optical switch units in different groups may use a same frequency, but the phase shifters need to be connected to different electrodes.
In an embodiment shown in
In an embodiment shown in
In an implementation manner, the coupler 112 is a 50:50 optical coupler.
In the foregoing embodiment, a corresponding optical switch unit may be driven by using a driving signal of a corresponding frequency. However, in another implementation manner, in addition to a frequency of a driving signal that affects a working status of a band-pass filter, amplitude of a driving signal is also one of factors that control the working status of the filter. For example, when the optical switch unit is a low-speed optical switch (such as a thermo-optic switch), switching time of the switch is generally relatively long, that is, a response frequency is extremely low. If the low-speed optical switch is driven by using an alternating current signal whose frequency is far higher than a switching frequency of the switch, a status of the optical switch is related only to amplitude of the alternating current signal, and high-frequency fluctuation of the alternating current signal has little impact on the switch status. A thermo-optic switch of a millisecond order of magnitude is used as an example. If the thermo-optic switch is driven by using an alternating current signal in MHz (a corresponding period is of a μs order of magnitude), high-speed fluctuation of an alternating current signal can only cause little-amplitude fluctuation of a status of the optical switch, and cannot cause large impact on the status of the optical switch. The status of the optical switch significantly changes only when amplitude of the alternating current signal changes.
As shown in waveform diagrams of
The filter 120 may be a band-pass filter in various forms. For example, in a first embodiment shown in
In
Different capacitance values and resistance values are used in a loop of each phase shifter, so that different phase shifters can receive driving signals of different frequencies. Statuses of different optical switches can be controlled by controlling amplitude of signals of different frequencies that are in the driving signals.
Isolation of a band-pass filter that is in a loop of a phase shifter can be enhanced by cascading multiple levels of low-pass filters and multiple levels of high-pass filters, so that the band-pass filter is less affected by another frequency.
A typical active band-pass filter is formed by the capacitors and the resistors that are in a loop of the foregoing integrated operational amplifier. Generally, an outband suppression feature of an active band-pass filter is better than that of a passive filter of a same level, so that crosstalk between loops of different phase shifters can be reduced.
Isolation of a band-pass filter can be improved by using a method in which multiple levels of active band-pass filters are cascaded or multiple levels of active low-pass filters and active high-pass filters are cascaded, so as to reduce crosstalk between loops of different phase shifters.
In another implementation manner, a circuit of an active band-pass filter may be built by using another linear device (such as a triode and a field effect transistor).
In a fourth embodiment shown in
of the LC resonant circuit, impedance of the LC resonant circuit is 0. When a frequency of a signal generated by the multi-frequency signal source deviates from the resonance frequency ω1, the LC resonant circuit presents specific impedance. Likewise, other LC resonant circuits in the diagram also have corresponding resonance frequencies
If proper inductance and capacitance values are selected, each LC resonant circuit presents a short-circuited state when receiving a signal whose frequency is the same as a resonance frequency of the LC resonant circuit, and presents extremely high impedance for a signal of another frequency, which is equivalent to an open circuit state. The amplification circuit that includes the integrated operational amplifier, the resistor, the capacitor, and the inductor amplifies a signal of the frequency ω1 by a multiple of R0/R1, amplifies a signal of the frequency ω2 by a multiple of R0/R2, and amplifies a signal of the frequency ωn by a multiple of R0/Rn.
All the R1, R2, and Rn are adjustable resistors. Amplification multiples of different frequency components amplified by the amplification circuit can be adjusted by adjusting different adjustable resistors, and an amplification multiple of another frequency component is not affected. In this way, amplitude of different frequencies of output signals can be independently adjusted.
Output signals of the multi-frequency signal source 210 may include only frequency components of ω1, ω2 and ωn, or may include another frequency component. The multi-frequency signal source 210 may be a wide-spectrum noise source.
The LC resonant circuit shown in
In a fifth embodiment shown in
When a status of an optical switch needs to be changed, a time domain waveform obtained by superimposing all frequency components needs to be recalculated, and the high-speed DAC re-sends a required driving signal according to a new waveform.
In a sixth embodiment shown in
S01. Send an optical switch status switching request to a multi-frequency driving signal source 200.
S02. Calculate a driving power vector c that a corresponding phase shifter requires.
S03. Calculate a power vector d=cT−1 of a driving signal that the multi-frequency driving signal source 200 needs to generate.
S04. The multi-frequency driving signal source 200 generates the driving signal according to the vector d.
If phase shifters of several optical switch units that share a pair of electrodes are respectively driven by driving signals of frequencies ω1, ω2, . . . , and ωn, output powers of multi-frequency driving signals of these frequencies are respectively a1, a2, . . . , and an, and after the driving signals pass through a filter, powers received by the phase shifters are respectively b1, b2, . . . , and bn.
It is assumed that specific crosstalk exists in the filter, and crosstalk between adjacent channels is p. That is, crosstalk of a power pω2 of a power ω2 exists in a phase shifter that receives ω1 and a phase shifter that receives ω3, which may be expressed by using a matrix, that is b=Ta, where b=[b1, b2, . . . , bn] and a=[a1, a2, . . . , an].
The foregoing matrix is a transmission function of a change from a signal power output by a multi-frequency signal source to a signal power received by a phase shifter. If a power vector of a driving signal that the phase shifter requires is c=[c1, c2, . . . , cn], a power d=cT−1 of each required frequency component of the multi-frequency signal source may be calculated by using a suppressed transmission function T, and then a power vector d of a driving signal that the multi-frequency signal source needs to generate may be calculated. A problem of crosstalk between driving signals of different phase shifters that is caused by poor isolation of a filter may be relieved by using this algorithm.
Referring to
S1. Divide optical switch units of an optical switch matrix into N groups, where N is a natural number greater than or equal to 1; each group of optical switch units shares a pair of electrodes, each pair of electrodes is configured to connect to a multi-frequency driving signal source, and each optical switch unit is connected to a band-pass filter and connects to the multi-frequency driving signal source by using the band-pass filter; and pass bands of M band-pass filters that are connected to M optical switch units in a same group are different, where M is a natural number greater than or equal to 2.
S2. The multi-frequency driving signal source outputs multiple driving signals of different frequencies that are corresponding to the pass bands of the M band-pass filters, so as to drive the group of optical switch units.
S3. When the optical switch unit is a low-speed switch, adjust amplitude of a driving signal to switch a status of the optical switch unit according to a switching request.
In the foregoing optical switch driving module and the optical switch driving method, an optical switch is driven by using an alternating current signal, and different optical switches are driven by using signals of different frequencies. This method is used to enable different optical switches to share a pair of chip electrodes, so as to effectively relieve a problem that driving electrodes around a large-scale optical switch chip are insufficient.
The foregoing descriptions are merely various specific embodiments of the present invention, and the solutions described in the embodiments may be used separately or may be used together. Variation or replacement readily figured out by a person skilled in the art within the technical scope disclosed in the present invention shall fall within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
This application is a continuation of International Application No. PCT/CN2014/094229, filed on Dec. 18, 2014, the disclosure of which is hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CN2014/094229 | Dec 2014 | US |
| Child | 15625829 | US |