Example photoconductive devices and example methods for using photoconductive devices are described. An example method may include providing a photoconductive device having a metal-semiconductor-metal structure. The method may also include controlling, based on a first input state, illumination of the photoconductive device by a first optical beam during a time period, and controlling, based on a second input state, illumination of the photoconductive device by a second optical beam during the time period. Further, the method may include detecting an amount of current produced by the photoconductive device during the time period, and based on the detected amount of current, providing an output indicative of the first input state and the second input state. The example devices can be used individually as discrete components or in integrated circuits for memory or logic applications.

The laser driver including a difference amplifier, a target potential circuit, an adjusting circuit, and bypass circuit is disclosed. The differential amplifier outputs a driving signal and a reverse driving signal having a phase opposite to a phase of the driving signal. The bypass circuit outputs an output current in response to the driving signal for generating a driving current for a semiconductor laser element that emits an optical signal in response to the driving signal. The adjusting circuit controls average potential of the driving signal and the reverse driving signal, so that the average potential becomes substantially equal to a target potential provided by the target potential circuit. The target potential corresponds to average optical power of the optical signal. When amplitude of the driving signal is changed for adjusting an extinction ratio of the optical signal, the adjusting circuit maintains the average optical power in a constant value.

A solid-state light source (SSLS) with light modulation control is described. A SSLS device can include a main p-n junction region configured for recombination of electron-hole pairs for light emission. A supplementary p-n junction region is proximate the main p-n junction region to supplement the recombination of electron-hole pairs, wherein the supplementary p-n junction region has a smaller electron-hole life time than the electron-hole life time of the main p-n junction region. The main p-n junction region and the supplementary p-n junction region operate cooperatively in a light emission state and a light turn-off-state. In one embodiment, the recombination of electron-hole pairs occurs in the main p-n junction region during a light emission state, and the recombination of electron-hole pairs occurs in the supplementary p-n junction region light during the light turn off-state.

A semiconductor device includes a series of layers formed on a substrate, including a first plurality of n-type layers, a second plurality of layers that form a p-type modulation doped quantum well structure (MDQWS), a third plurality of layers disposed between the p-type MDQWS and a fourth plurality of layers that form an n-type MDQWS, and a fifth plurality of p-type layers. The first plurality of layers includes a first etch stop layer of n-type formed on an n-type contact layer. The third plurality of layers includes a second etch stop layer formed above the p-type MDQWS and a third etch stop layer formed above and offset from the second etch stop layer. The fifth plurality of layers includes a fourth etch stop layer of p-type formed above the n-type MDQWS and a fifth etch stop layer of p-type doping formed above and offset from the fourth etch stop layer.

The laser driver including a difference amplifier, a target potential circuit, an adjusting circuit, and bypass circuit is disclosed. The differential amplifier outputs a driving signal and a reverse driving signal having a phase opposite to a phase of the driving signal. The bypass circuit outputs an output current in response to the driving signal for generating a driving current for a semiconductor laser element that emits an optical signal in response to the driving signal. The adjusting circuit controls average potential of the driving signal and the reverse driving signal, so that the average potential becomes substantially equal to a target potential provided by the target potential circuit. The target potential corresponds to average optical power of the optical signal. When amplitude of the driving signal is changed for adjusting an extinction ratio of the optical signal, the adjusting circuit maintains the average optical power in a constant value.

A III-V semiconductor device in an optical transceiver includes a signal processing circuit. The signal processing circuit includes processing circuitry configured to receive or transmit an electrical signal corresponding to an optical signal, and feedback control circuitry communicatively coupled to the processing circuitry by a circuit loop. The feedback control circuitry is configured to sense a characteristic of the electrical signal, and based on the sensed characteristic, transmit over the circuit loop a feedback signal to the processing circuitry. The circuit loop includes a first transistor formed using a III-V semiconductor material and configured to function as a first sensing resistor having a first resistance value that limits loading applied to the processing circuitry by the feedback control circuitry.

A photonic crystal surface-emitting laser includes a light emitting module and a driving module. The light emitting module includes a photonic crystal layer, an active light emitting layer on a side of the photonic crystal layer, a first electrode on a side of the active light emitting layer facing away from the photonic crystal layer, and a second electrode partially on the side of the active light emitting layer facing away from the photonic crystal layer. The driving module makes electrical contact with surfaces of the first electrode and the second electrode facing away from the photonic crystal layer. The driving module outputs driving signals to the first electrode and the second electrode to drive the active light emitting layer to generate photons. The photons are incident into the photonic crystal layer to generate a laser light through oscillation on Bragg diffraction. An optical system is also disclosed.