Described herein are photonic integrated circuits (PICs) comprising a semiconductor optical amplifier (SOA) to output a signal comprising a plurality of wavelengths, a sensor to detect data associated with a power value of each wavelength of the output signal of the SOA, a filter to filter power values of one or more of the wavelengths of the output signal of the SOA, and control circuitry to control the filter to reduce a difference between a pre-determined power value of each filtered wavelength of the output signal of the SOA and the detected power value of each filtered wavelength of the output signal of the SOA.

An optical amplifier (21) configured to operate with saturated output power is coupled on the receive side with respect to a receiver (18) coupled to a transmitter (17) via an optical fiber (14). The saturated output power is represented as a saturation characteristic drawing a flat curve in which, as power (input optical power) of an optical signal (22i) inputted to the optical amplifier (21) increases in excess of a given level, the variation in power (output optical power) of an optical signal (22o) outputted from the optical amplifier (21) decreases. Consequently, information represented by the optical signal (22o) inputted from the optical amplifier (21) to the receiver (18) can be properly received.

Disclosed are techniques and amplifier stages that include wave division multiplexers, semiconductor optical amplifiers and wave division demultiplexers that amplify optical signals. An input optical signal having a first bandwidth is partitioned into a plurality of subband optical signals by thin film filters tuned to a selected bandwidth that is less than the first bandwidth. Each of the plurality of subband optical signals has a bandwidth that is a portion of the first bandwidth. Each subband optical signal is input into a semiconductor optical amplifier that is tuned to the respective portion of the first bandwidth that corresponds to the subband optical signal. The combination of the partitioned input optical signal and tuned semiconductor optical amplifiers provides improved optical signal transmission performance by reducing polarization dependent gain.

An optical receiver includes an optical amplifier that amplifies a received optical signal containing multiple wavelengths, a monitor circuit that monitors light intensities of the demultiplexed optical signal, a processor, and a memory having information representing a relationship between a total incident light intensity of the optical signal incident onto the optical amplifier and gains of the optical amplifier for the respective wavelengths. The processor repeats first calculation for determining the gains of the respective wavelengths from the memory, based on a drive current for driving the optical amplifier and an estimation value of the total incident light intensity of the optical signal, second calculation for calculating the incident light intensities of the respective wavelengths of the optical signal based on the gains and the monitored light intensities, and third calculation to calculate the total incident light intensity of the optical signal, until the total incident light intensity converges.

Disclosed herein are methods, devices, and system for beam forming and beam steering within ultra-wideband, wireless optical communication devices and systems. According to one embodiment, a free space optical (FSO) communication apparatus is disclosed. The FSO communication apparatus includes a semiconductor optical device configured to have a transient response time of less than 500 picoseconds (ps), a lens, and a first band select filter.

Disclosed herein are devices, methods, and systems for selectively amplifying optical signals using an optical circuit. The optical circuit includes an input port to receive a plurality of input laser signals and a switching array connected to the input port. The switching array includes a plurality of switching optical amplifiers configured to amplify a laser signal of the plurality of input laser signals as an amplified laser signal and absorb the remaining of the plurality of input laser signals. The optical circuit also includes a splitting circuit connected to the switching array. The splitting circuit is configured to split the amplified laser signal into a plurality of output laser signals.

Disclosed herein are methods, devices, and system for beam forming and beam steering within ultra-wideband, wireless optical communication devices and systems. According to one embodiment, a free space optical (FSO) communication apparatus is disclosed. The FSO communication apparatus includes an array of optical sources wherein each optical source of the array of optical sources is individually controllable and each optical source configured to have a transient response time of less than 500 picoseconds (ps).

An optical network using an optical amplifier in a gain saturation region includes an optical transmission apparatus. The optical transmission apparatus includes an optical transmitter configured to output an optical signal, a semiconductor optical amplifier (SOA) configured to amplify the optical signal outputted through the optical transmitter, and a controller configured to control the SOA to operate in a gain saturation region or a linear gain region depending on whether a forward error correction (FEC) function is used in the optical network.

Disclosed herein are methods, devices, and system for beam forming and beam steering within ultra-wideband, wireless optical communication devices and systems. According to one embodiment, a free space optical (FSO) communication apparatus is disclosed. The FSO communication apparatus includes an array of optical sources wherein each optical source of the array of optical sources is individually controllable and each optical source configured to have a transient response time of less than 500 picoseconds (ps).

Techniques for improving redundancy in semiconductor-based optical communication systems are provided. For example, two or more semiconductor optical amplifiers (SOAs) may be provided in an optical repeater, and each SOA may form a respective amplification path. When failure occurs on a first SOA, a second SOA that is different from the first SOA can be selected. In one example, the selection may be based on wavelength division multiplexing (WDM), and in another example, the selection may be based on optical switching. The two or more SOAs (and other optical components) may be integrated in the same substrate package.