Provided are methods for optical communication, comprising: generating a phase difference signal with heterodyne or homodyne phase-locked-loop (PLL) from between an optical input signal and a local laser source; controlling the local laser source with the phase difference signal; demodulating the optical input signal using the local laser source as a carrier signal to generate a baseband output signal; and controlling the heterodyne or homodyne PLL and the demodulation with an electrical oscillator signal. Also provided are related methods.

An underwater communications system may include a first device and a second device being movable relative to one another. The first device may include a first laser transmitter configured to generate a first laser beam having a selectable spatiotemporal beam shape from among a plurality thereof, and a first controller coupled to the first laser transmitter and configured to select a spatiotemporal beam shape for the first laser beam from among the spatiotemporal beam shapes. The second device may include a second laser receiver configured to receive the first laser beam, and a second controller coupled to the second laser receiver.

An optical network component, system, and method are herein described. The system and method include introducing an AM tone and data to an optical modulator generating a modulated optical signal, measuring an amplitude response of the AM tone within the modulated optical signal, calculating a frequency response based on the amplitude response, and calibrating the optical modulator with the frequency response.

A device includes a photonic integrated circuit having an optical phased array. The optical phased array includes multiple array elements, where each array element includes (i) an antenna element configured to transmit or receive optical signals and (ii) a phase modulator configured to phase-shift the optical signals transmitted or received by the antenna element. The device also includes multiple digital register in integrated circuit (DRIIC) cells, where each DRIIC cell is associated with one of the array elements. The DRIIC cells are configured to receive digital inputs and to provide outputs to the phase modulators of the associated array elements in order to control the phase-shifts of the optical signals transmitted or received by the antenna elements based on the digital inputs.

The invention relates to a method and apparatus of operating a bidirectional optical transmission link. The optical transmission link includes a first and a second optical transceiver at a dedicated end of the optical transmission link and an optical path connecting the first and second optical transceiver. The optical transceivers apply the methods of converting an electrical digital transmit signal into an electrical PAM-n transmit signal, pre-emphasizing the electrical PAM-n transmit signal) by digital filtering and using the pre-emphasized electrical PAM-n signal.sub.2) as modulating signal for optically modulating an optical carrier signal. The optical modulation method deployed is configured to create an optical PAM-n transmit signal with a positive or negative chirp. For initializing the optical transmission link (100), an initialization process is performed in which at least one loop including the following steps is run through creating, in the first optical transceiver, an optical PAM-n training transmit signal and transmitting it to the second optical transceiver, the optical PAM-n training transmit signal being created using an electrical PAM-n training transmit signal including a binary training sequence. Initial values for filter parameters are used for pre-emphasizing the electrical PAM-n training transmit signal and an initial value is used for a chirp parameter that defines the positive or negative chirp of the optical PAM-n training transmit signal receiving, in the second optical transceiver, the optical PAM-n training transmit signal as an optical PAM-n training receive signal using direct detection. The optical PAM-n training receive signal is converted into an electrical PAM-n training receive signal. The method includes obtaining sampled values of the electrical PAM-n training receive signal (RP.sub.el,1) by sampling this signal at predetermined points in time; and using the sampled values obtained and corresponding sampled values of an ideal electrical PAM-n transmit signal to determine operating values for the filter parameters and an operating value for the chirp parameter.

An optical device comprises a laser diode configured to emit an optical signal, wherein the optical signal diffracts into a plurality of emitted optical signals, and a submount comprising a mirror, wherein the mirror is configured to at least partially reflect and redirect the plurality of emitted optical signals to produce a plurality of reflected optical signals, and wherein the mirror is further configured to substantially reshape a vertical far field angle of the optical signal.

An injection locked transmitter for an optical communication network includes a primary seed laser source input substantially confined to a single longitudinal mode, an input data stream, and a laser injected modulator including at least one secondary laser having a resonator frequency that is injection locked to a frequency of the single longitudinal mode of the primary seed laser source. The laser injected modulator is configured to receive the primary seed laser source input and the input data stream, and output a laser modulated data stream.

An apparatus includes: a laser driver configured to output a laser diode current in accordance with a transmit data, a bias control code, and a modulation control code, a laser diode configured to receive the laser diode current and output a light signal, a photodiode configured to receive the light signal and output a photodiode current, a reference driver configured to output a reference current in accordance with the transmit data, the transmit enable signal, a reference bias code, and a reference modulation code, a two-fold comparison circuit configured to compare the photodiode current and the reference current and output a first decision and a second decision, and a DSP configured to adjust the bias control code and the modulation control code in accordance with the first decision and a second decision. A method provides reliable light output using the described apparatus.

An optical device includes an input array, an output array and a waveguide array. The input array is connected to a first slab structure, while the output array is connected to a second slab structure. The waveguide array is optically coupled to the first slab structure and the second slab structure. The waveguide array includes a first connecting part, a second connecting part and a plurality of waveguide channels. The first connecting part is joined with the first slab structure. The second connecting part is joined with the second slab structure, wherein the second connecting part includes a central portion and at least one flank portion, the central portion is connected to and overlapped with the second slab structure, and the at least one flank portion extends over a side surface of the second slab structure. The waveguide channels are joining the first connecting part to the second connecting part.

An apparatus is provided that includes a modulator and an optical transmitter coupled to the modulator and configured to emit an optical beam that the modulator is configured to modulate with data. The optical transmitter may thereby be configured to emit the optical beam carrying the data and without artificial confinement for receipt by an optical receiver configured to detect and recover the data from the optical beam. The optical transmitter may be configured to emit the optical beam with a divergence angle greater than 0.1 degrees, and with a photonic efficiency of less than 0.05%. The photonic efficiency may relate a number of photons of the optical beam detectable by the optical receiver, to a number of photons of the optical beam emitted by the optical transmitter.