Patent Application
20130202312
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Conventional Dense Wavelength Division Multiplexing (DWDM) systems employ a laser in combination with a series of modulators, which serve the function of manipulating the amplitude, phase, and/or frequency of the laser beam to create an optical signal based on an incoming electrical signal. Multiple modulators are typically employed to multiplex several different electrical signals, such as radio frequency signals, onto a single optical signal by employing each modulator or modulator pair, depending on implementation, to alter a specific wavelength of light. The resulting optical signal may then be placed on an optical fiber for transmission.
One approach to creating a transmitter for use in a DWDM system is to use discrete modulators. This implementation method forces the creation of an extremely complex and expensive transmitter architecture requiring a large number of optical functions and elements. This complexity problem has led to research into large scale photonic integration, which would allow the integration of multiple optical functions and wavelength channels onto a single circuit component. The integrated approach reduces architecture complexity, increases system reliability, and reduces system power consumption compared to systems employing discrete optical components.
Most DWDM networks employ Mach-Zehnder Modulators (MZM) to modulate optical signals. These MZMs are typically made of lithium niobate because of its high electro-optical coefficients and high optical transparency in the near infrared wavelengths. Lithium niobate is highly anisotropic, which requires its input ports to be positioned in the opposite direction from its output ports. Further, the anisotropic nature of a typical MZM prevents significant on-chip lightpath bending. These design constraints have forced all previous attempts at large scale photonic integration to rely on a monolithic architecture. This monolithic structure requires incoming electrical signal routing related to the MZMs at the center of the monolith to become increasingly complex to the point of impossibility depending on the number of MZMs employed. This in turn creates an upper limit on the number channels available to a monolithic system. In high speed systems, the difference in length between the simple short routing to the outer MZMs when compared to the longer complex routings to the inner MZMs also causes a significant difference in the propagation of the associated electrical signals. This difference in propagation delay must also be considered by other components of the system, creating further system complexity and cost.
In an embodiment, the disclosure includes an apparatus comprising a first circuit component comprising a plurality of optical devices. Each optical device has an optical input port and an optical output port. All of the optical input ports and all of the optical output ports are positioned on a first side of the circuit component.
In an embodiment, the disclosure includes a circuit component comprising a plurality of optical devices. The circuit component further comprises a plurality of electrical inputs coupled to the optical devices and positioned on a first side of the circuit component. The circuit component also comprises a plurality of optical input ports coupled to the optical devices and positioned on a second side of the circuit component that does not share any edges with the first side.
In an embodiment, the disclosure also includes a method comprising directing an optical signal from an optical input port to an optical device, redirecting the optical signal at least 180 degrees, modifying the optical signal with the optical device, and directing the optical signal to an optical output port.
These and other features will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings and claims.
For a more complete understanding of this disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts.
It should be understood at the outset that, although an illustrative implementation of one or more embodiments are provided below, the disclosed systems and/or methods may be implemented using any number of techniques, whether currently known or in existence. The disclosure should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, including the exemplary designs and implementations illustrated and described herein, but may be modified within the scope of the appended claims along with their full scope of equivalents.
Disclosed herein is a series of optical building blocks, which may be employed for large scale non-monolithic photonic integration. Isotropic materials are employed to allow optical signals to be bent at relatively sharp angles in a small area on a circuit component. Using this property, the devices disclosed herein have both optical inputs and optical outputs positioned on the same side of the circuit component. The optical inputs may be modulated using MZMs to create optical signals which may be multiplexed with other signals or otherwise employed by other related components. The MZMs may be made from Group 13-15 (also known as Group IIIB-VB) materials and may be controlled by an electrical input signal. The electrical input may be positioned on the opposite side of the circuit component from the optical inputs and outputs. Such positioning allows for simple electrical signal routing which reduces complexity and allows for relatively uniform electrical path length. Uniform electrical path length further reduces complexity by ensuring relatively uniform electrical signal propagation delay, thereby reducing or eliminating the need for devices to compensate for differing propagation delay on different electrical paths. The embodiments discussed herein may be used to create a photonic integrated device (PID) and/or a photonic integrated circuit (PIC). A PID may be a PIC that is integrated in a non-monolithic fashion.
The optical device 100 may also be configured to receive an electrical input signal 109. The electrical input signal 109 may be connected to the third lightpath 105 by an electrical input 110 and connected to a ground or sent to another component by an electrical output 111. The electrical input signal 109 may cause a modification in the optical signal in the third lightpath 105. The optical signal in the second lightpath 104 may then be combined with the optical signal from the third lightpath 105 by a 2:1 coupler 106, such as a 2:1 MMI coupler, creating an optical output signal 108 that is modulated by the electrical input signal 109. The optical output signal 108 may then be transmitted along a fourth lightpath to the optical output port 107 and be transmitted to other components.
The circuit component 200 may further comprise one or more electrical input ports 201, which are positioned on a second side 203 of the circuit component 200. The second side 203 of the circuit component 200 may be the opposite side of the circuit component 200 from the first side 202 in that it may not be the same as and may not share any edges with the first side 202. One skilled in the art will recognize that each electrical input 110 may be connected through the electrical input ports 201, be connected to an optical device 100, and be paired with a corresponding electrical output 111 for proper transfer of the electrical input signals 109. The electrical output 111 may be a ground or may connect to another component. In
As shown in
One skilled in the art will recognize that a Mach-Zehnder Interferometer (MZI) which is useful for QPSK, may be created using circuit component 500 or circuit component 600. The optical device array of circuit component 500 or 600 may be optically aligned or coupled with other components such as a planar lightwave circuit (PLC) or similar devices. The circuit component 500 or circuit component 600 may split a single optical input signal 101 into two equivalent optical output signals 108. The equivalent signals may be transmitted to the PLC to be recombined and tested for constructive or destructive interference.
As shown above, the various embodiments of the optical device array disclosed herein may be used to transmit an optical signal to an optical device from an optical input port, redirect the optical signal about 180 degrees, modify the optical signal with the optical device, and transmit the optical signal to an optical output port. The optical input ports and the optical output ports may be positioned on the same side of a circuit component. Modifying an optical signal may comprise modulating the signal or performing other signal processing methods on the signal.
Multiple embodiments are disclosed and variations, combinations, and/or modifications of the embodiment(s) and/or features of the embodiment(s) made by a person having ordinary skill in the art are within the scope of the disclosure. Alternative embodiments that result from combining, integrating, and/or omitting features of the embodiment(s) are also within the scope of the disclosure. Where numerical ranges or limitations are expressly stated, such express ranges or limitations may be understood to include iterative ranges or limitations of like magnitude falling within the expressly stated ranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than 0.10 includes 0.11, 0.12, 0.13, etc.). For example, whenever a numerical range with a lower limit, Rl, and an upper limit, Ru, is disclosed, any number falling within the range is specifically disclosed. In particular, the following numbers within the range are specifically disclosed: R=Rl+k*(Ru−Rl), wherein k is a variable ranging from 1 percent to 100 percent with a 1 percent increment, i.e., k is 1 percent, 2 percent, 3 percent, 4 percent, 5 percent, . . . , 50 percent, 51 percent, 52 percent, . . . , 95 percent, 96 percent, 97 percent, 98 percent, 99 percent, or 100 percent. Moreover, any numerical range defined by two R numbers as defined in the above is also specifically disclosed. Use of the term “optionally” with respect to any element of a claim means that the element is required, or alternatively, the element is not required, both alternatives being within the scope of the claim. Use of broader terms such as comprises, includes, and having may be understood to provide support for narrower terms such as consisting of, consisting essentially of, and comprised substantially of. Accordingly, the scope of protection is not limited by the description set out above but is defined by the claims that follow, that scope including all equivalents of the subject matter of the claims. Each and every claim is incorporated as further disclosure into the specification and the claims are embodiment(s) of the present disclosure. The discussion of a reference in the disclosure is not an admission that it is prior art, especially any reference that has a publication date after the priority date of this application. The disclosure of all patents, patent applications, and publications cited in the disclosure are hereby incorporated by reference, to the extent that they provide exemplary, procedural, or other details supplementary to the disclosure.
While several embodiments have been provided in the present disclosure, it may be understood that the disclosed systems and methods might be embodied in many other specific forms without departing from the spirit or scope of the present disclosure. The present examples are to be considered as illustrative and not restrictive, and the intention is not to be limited to the details given herein. For example, the various elements or components may be combined or integrated in another system or certain features may be omitted, or not implemented.
In addition, techniques, systems, subsystems, and methods described and illustrated in the various embodiments as discrete or separate may be combined or integrated with other systems, modules, techniques, or methods without departing from the scope of the present disclosure. Other items shown or discussed as coupled or directly coupled or communicating with each other may be indirectly coupled or communicating through some interface, device, or intermediate component whether electrically, mechanically, or otherwise. Other examples of changes, substitutions, and alterations are ascertainable by one skilled in the art and may be made without departing from the spirit and scope disclosed herein.
