A multifunctional photonic integrated circuit (PIC) suitable for the manufacture of fiber optic gyroscopes (FOG) is described. The PIC is constructed and arranged to exhibit a scale factor of substantially high stability and accuracy. The PIC may comprise, for example, a high optical birefringence and low propagation loss waveguide, a low wavelength-dependent split-ratio Y-junction, a high extinction ratio linear polarizer, and high efficiency fiber-to-waveguide mode-size converters. Considerations for ensuring high-level FOG performance are addressed by, for example, optimization of waveguide structure, functional requirements for individual components, and combined effects of the circuit layout. A high-end, tactical grade FOG may be built using the disclosed PIC, after connecting to polarization maintaining optical fiber coil, a light source, and a photodetector.

An optical circuit for routing a signal includes a coupler and first and second waveguides. The coupler has an input for the signal and has first and second outputs. The first waveguide has a first optical connection to the first output, and the second waveguide has a second optical connection to the second output. Both waveguides have the same propagation length. The first and second waveguides include different widths at the respective optical connections to the respective outputs. This coupler can be used with another input couplers, two additional waveguides, and two 2×2 output couplers to provide a 90-degree hybrid for mixing signal light and local oscillator light in a coherent receiver or the like.

Improvements to gratings for use in waveguides and methods of producing them are described herein. Deep surface relief gratings (SRGs) may offer many advantages over conventional SRGs and Bragg gratings, an important one being a higher S-diffraction efficiency. In one embodiment, deep SRGs can be implemented as polymer surface relief gratings or evacuated Bragg gratings (EBGs). EBGs can be formed by first recording a holographic polymer dispersed liquid crystal (HPDLC) grating. Removing the liquid crystal from the cured grating provides a polymer surface relief grating. Polymer surface relief gratings have many applications including for use in waveguide-based displays.

Techniques for tuning an optical communication system are disclosed. The system includes a first signal path for transmitting data, including an optical source, a first one or more variable optical attenuators (VOAs), a modulator, and a transmission fiber. The system further includes a second signal path for receiving data, including a receiver fiber and a second one more VOAs. The first one or more VOAs are tuned using the optical source in the first signal path for transmitting data, based on comparing a plurality of optical signal power values in the first path while a first tuning mode is enabled. The second one or more VOAs are tuned, using the optical source in the first signal path for transmitting data, based on comparing a plurality of optical signal power values in the second path while a second tuning mode is enabled.

Techniques for tuning an optical communication system are disclosed. The system includes a first signal path for transmitting data, including an optical source, a first one or more variable optical attenuators (VOAs), a modulator, and a transmission fiber. The system further includes a second signal path for receiving data, including a receiver fiber and a second one more VOAs. The first one or more VOAs are tuned using the optical source in the first signal path for transmitting data, based on comparing a plurality of optical signal power values in the first path while a first tuning mode is enabled. The second one or more VOAs are tuned, using the optical source in the first signal path for transmitting data, based on comparing a plurality of optical signal power values in the second path while a second tuning mode is enabled.

An optical circuit for routing a signal includes a coupler and first and second waveguides. The coupler has an input for the signal and has first and second outputs. The first waveguide has a first optical connection to the first output, and the second waveguide has a second optical connection to the second output. Both waveguides have the same propagation length. The first and second waveguides include different widths at the respective optical connections to the respective outputs. This coupler can be used with another input couplers, two additional waveguides, and two 2×2 output couplers to provide a 90-degree hybrid for mixing signal light and local oscillator light in a coherent receiver or the like.

An optical assembly for optical signal processing including a first input for coupling in a first light signal; a second input for coupling in a second light signal; a first beam splitter for splitting the first light signal into a first part and a second part; a second beam splitter for splitting the second light signal into a first part and a second part; a superposing unit; a detector; an electronic signal processing unit; at least one actuating unit; and a delay line for generating a delay of the running time of the first part of the first light signal and of the first part of the second light signal up to the superposing unit. The delay line is configured such that the first part of the first light signal and the first part of the second light signal pass through the delay line in opposite directions.

An optical-fiber measurement system includes an optical transceiver comprising an optical transmitter and an optical receiver. A multi-core optical fiber has a proximal end with a first optical core coupled to the transceiver and a second optical core coupled to the transceiver, and a distal end with the first optical core coupled to a sample path that is configured to convey light collected from a sample positioned external to the multi-core optical fiber and the second optical core coupled to a reference path such that the sample path and the reference path experience mostly a same disturbance along the multi-core optical fiber. The optical receiver is configured to interferometrically detect light from the sample path and light from the reference path.

The present disclosure is directed to photonic wavelength division multiplexing (WDM) receivers with polarization diversity and/or low reflectance. In embodiments, a WDM receiver is provided with a splitter, a plurality of waveguides and a plurality of photodetectors in series. The waveguides having particular equal path lengths relationship from the splitter to respective ones of the photodetectors. In other embodiments, the WDM receiver is provided with a splitter, a looped waveguide, a plurality of photodetectors, and a plurality of variable optical attenuators (VOAs). The VOAs are configured to suppress reflection of signal beams back to the transmitter. In various embodiments, the WDM receiver is a receiver sub-assembly of a silicon photonic transceiver disposed in a silicon package. Other embodiments may be described and/or claimed.

Disclosed herein are optical integration technologies, designs, systems and methods directed toward Optical Coherence Tomography (OCT) and other interferometric optical sensor, ranging, and imaging systems wherein such systems, methods and structures employ tunable optical sources, coherent detection and other structures on a single or multichip monolithic integration. In contrast to contemporary, prior-art OCT systems and structures that employ simple, miniature optical bench technology using small optical components positioned on a substrate, systems and methods according to the present disclosure employ one or more photonic integrated circuits (PICs), use swept-source techniques, and employ a widely tunable optical source(s).

In another embodiment the system uses an optical photonic phased array. The phase array can be a static phased array to eliminate or augment the lens that couples light to and from a sample of interest or can be static and use a spectrally dispersive antenna and a tunable source to perform angular sweeping. The phased array can be active in 1 or 2 dimensions so as to scan the light beam in angle. The phased array can also adjust focus. The phased array can implement an optical waveform that will extend depth of field focus for imaging. The phase array can also be a separate standalone element that is fed by one or more optical fibers. The phased array can be for scanning a biomedical specimen used in conjunction with a swept-source OCT system, can be used in a free-space coherent optical communication system for beam pointing or tracking, used in LIDAR applications, or many other beam control or beam steering applications.