A passive dual polarization unit and coherent transceiver and/or receiver including one or more passive dual polarization units are provided. An example passive dual polarization unit includes a polarization splitter configured to split an input signal into a TE mode and TM mode signals; TE/TM splitters each designed to split the TE/TM mode signals into first TE/TM signals and second TE/TM signals; a first TE signal polarization rotation component for receiving the first TE signal and providing a third TM signal having the same magnitude and time dependence as the first TE signal; a first TM signal polarization rotation component for receiving the first TM signal and providing a third TE signal having the same magnitude and time dependence as the first TM signal; and TE/TM couplers that couple the second TE/TM signals and the third TE/TM signals to generate output TE/TM signals.

A random acoustic phase scrambler device is installed in-line with a telecommunications fiber link to prevent voice detection via fiber links. The device includes a transducer to produce vibrations; a length of optical fiber positioned to receive the vibration from the transducer; and a random acoustic phase driver configured to control the intensity and frequency of the vibrations. The transducer produces randomized vibrations within an acoustic bandwidth. The device is configured to introduce device-induced phase changes to signals within the telecommunications fiber link. The bandwidth of the device-induced phase changes is greater than the bandwidth of voice-induced phase changes, and the device-induced phase changes are greater in intensity than the voice-induced phase changes. The device-induced phase changes mask voice-induced phase changes through the telecommunications fiber link that are otherwise detectable by voice detection equipment tapped to the telecommunications fiber link.

A circuit for detecting an optical data signal includes a photonics substrate and first and second photodiodes formed in the photonics substrate. The first photodiode is configured to receive, via an input port formed in the photonics substrate, a first portion of the optical data signal and convert light power of the first portion of the optical data signal to generate a first current based on the optical data signal. The second photodiode is configured to output a second current without receiving any portion of the optical data signal. The second current corresponds to a dark current induced in the second photodiode. The circuit is configured to subtract the second current from the first current to generate an output signal corresponding to a power of the optical data signal without dark current induced in the first photodiode.

A circuit for detecting an optical data signal includes a photonics substrate and first and second photodiodes formed in the photonics substrate. The first photodiode is configured to receive, via an input port formed in the photonics substrate, a first portion of the optical data signal and convert light power of the first portion of the optical data signal to generate a first current based on the optical data signal. The second photodiode is configured to output a second current without receiving any portion of the optical data signal. The second current corresponds to a dark current induced in the second photodiode. The circuit is configured to subtract the second current from the first current to generate an output signal corresponding to a power of the optical data signal without dark current induced in the first photodiode.

An optical transmission/reception unit includes a carrier rotatable around an axis of rotation, an optical receiver arranged at the carrier on the axis of rotation so as to receive an optical reception signal from a first direction, an optical transmitter arranged at the carrier adjacent to the optical receiver so as to emit an optical transmission signal in a second direction, and a transmission/reception optic arranged at the carrier on the axis of rotation above the optical receiver and extending across the optical receiver and the optical transmitter, wherein the transmission/reception optic includes a reception optic and a transmission optic arranged in the reception optic, wherein the reception optic is configured to guide the optical reception signal striking the transmission/reception optic towards the optical receiver on the axis of rotation.

An optical transmission/reception unit includes a carrier rotatable around an axis of rotation, an optical receiver arranged at the carrier on the axis of rotation so as to receive an optical reception signal from a first direction, an optical transmitter arranged at the carrier adjacent to the optical receiver so as to emit an optical transmission signal in a second direction, and a transmission/reception optic arranged at the carrier on the axis of rotation above the optical receiver and extending across the optical receiver and the optical transmitter, wherein the transmission/reception optic includes a reception optic and a transmission optic arranged in the reception optic, wherein the reception optic is configured to guide the optical reception signal striking the transmission/reception optic towards the optical receiver on the axis of rotation.

Disclosed are systems for transmitting and receiving a radio frequency (RF) signal and an optical signal. One system may include a communication terminal comprising a primary concave reflector providing a first focal length to a focal point, and a secondary concave reflector providing a second focal length to the focal point. The communication terminal may further comprise an optical transceiver facing the secondary concave reflector, and one or more RF transceivers facing the primary concave reflector. The optical transceiver may be configured to transmit and receive the optical signal via the primary and secondary concave reflectors through the focal point, and the one or more RF transceivers may be configured to transmit and receive the RF signal via the primary concave reflector. The one or more RF transceivers may be positioned adjacent to the focal point and offset from a path of the optical signal.

A bidirectional transceiver includes a transmitter and a receiver that respectively transmits a local signal to and receives remote signal from a common bidirectional communication channel, thus the bidirectional channel signal is the superimposition of the local and remote signals. The bidirectional transceiver also includes a transmit canceller that substantially removes the local transmitted signal from the superimposed signals on the bidirectional channel before the local receiver. The remote signal is transmitted by a remote transceiver over the bidirectional channel. A sampling phase is set, based on timing information in the received remote signal, and the received signal is sampled. Timing relation of transitions in the local transmit signal relative to the receiver sampling phase is set such that transmit signal cancellation is optimum at receiver sampling phase, by changing the delay applied to the local transmit signal. To keep the timing relation of the local transmit signal relative to the remote transceiver, a second delay is applied to the local transmit signal before transmission into the bidirectional channel that provides a delay substantially same as the first delay but opposite in direction.

A bidirectional transceiver includes a transmitter and a receiver that respectively transmits a local signal to and receives remote signal from a common bidirectional communication channel, thus the bidirectional channel signal is the superimposition of the local and remote signals. The bidirectional transceiver also includes a transmit canceller that substantially removes the local transmitted signal from the superimposed signals on the bidirectional channel before the local receiver. The remote signal is transmitted by a remote transceiver over the bidirectional channel. A sampling phase is set, based on timing information in the received remote signal, and the received signal is sampled. Timing relation of transitions in the local transmit signal relative to the receiver sampling phase is set such that transmit signal cancellation is optimum at receiver sampling phase, by changing the delay applied to the local transmit signal. To keep the timing relation of the local transmit signal relative to the remote transceiver, a second delay is applied to the local transmit signal before transmission into the bidirectional channel that provides a delay substantially same as the first delay but opposite in direction.

A 6.4 Tbps silicon-based photonics engine transceiver chip module for high-speed optical communication manufactured based on processing techniques of semiconductors such as silicon-on-insulator (SOI) and indium phosphide (InP). The photonics engine transceiver chip module uses a silicon photonic chip as a substrate, and optical chips of an InP laser and an optical amplifier are heterogeneously integrated with the silicon photonic chip through bonding or flip-chip soldering. As a pump light source, the laser generates a soliton-based optical frequency comb by using an ultra-low loss silicon nitride (SiN) resonator cavity, and can be used as a multi-wavelength laser. This reduces use of a single-wavelength laser chip, reduces a power consumption and heat conduction of a laser in an optical chip of a photonic engine, and improves an integration level of an optical device. The optical frequency comb generates an optical carrier with wide bandwidth coverage and a large quantity of wavelengths.