An apparatus is described which uses directly modulated InGaN Light-Emitting Diodes (LEDs) or InGaN lasers as the transmitters for an underwater data-communication device. The receiver uses automatic gain control to facilitate performance of the apparatus over a wide-range of distances and water turbidities.

A method and system, in an optical receiver, includes receiving a first photocurrent from a first photodetector and a second photocurrent from a second photodetector; amplifying the first photocurrent with a first amplifier to provide a first output signal and the second photocurrent with a second amplifier to provide a second output signal; adjusting a frequency response of a first path the first photocurrent and a second path of the second photocurrent; and determining a difference between the adjusted first photocurrent and the adjusted second photocurrent.

An optical receiver can implement a transimpedance amplifier (TIA) to process received light using a closed loop optical pre-amplification. The optical receiver can use an average input value of the TIA to control an semiconductor optical amplifier (SOA) or pre-amplification as received average signal varies. The optical receiver can include a gain controller for the TIA that can measure the TIA swing to adjust the gain of the SOA to pre-amplify received light in a closed loop control configuration.

Disclosed is an optical receiver. The optical receiver includes an optical splitter that splits an external light signal to output a first light signal and a second light signal, a first amplifier that amplifies the first light signal in a linear gain section to output an amplified first light signal, a second amplifier that amplifies the second light signal in a saturation gain section to output an amplified second light signal, a polarization division hybrid that outputs an in-phase hybrid light signal and a quadrature-phase hybrid light signal, based on a reference light signal and the amplified second light signal, and an optoelectronic conversion unit that outputs an electrical signal, based on the amplified first light signal, the in-phase hybrid light signal, and the quadrature-phase hybrid light signal.

Disclosed is an optical receiver. The optical receiver includes an optical splitter that splits an external light signal to output a first light signal and a second light signal, a first amplifier that amplifies the first light signal in a linear gain section to output an amplified first light signal, a second amplifier that amplifies the second light signal in a saturation gain section to output an amplified second light signal, a polarization division hybrid that outputs an in-phase hybrid light signal and a quadrature-phase hybrid light signal, based on a reference light signal and the amplified second light signal, and an optoelectronic conversion unit that outputs an electrical signal, based on the amplified first light signal, the in-phase hybrid light signal, and the quadrature-phase hybrid light signal.

An optical receiver is disclosed, including an optoelectronic detector, a transimpedance amplification (TIA) circuit, a single-ended-to-differential converter, an I/O interface, and a controller. The optoelectronic detector, having bandwidth lower than required system transmission bandwidth, converts an optical signal into a current signal. The TIA circuit compensate gain for the received current signal based on a received control signal, to obtain a voltage signal, where a frequency response value of the current signal within first bandwidth is greater than that within the bandwidth of the optoelectronic detector, and any frequency in the first bandwidth is not lower than an upper cut-off frequency of the optoelectronic detector. The single-ended-to-differential converter converts the voltage signal into a differential voltage signal. The I/O interface outputs the differential voltage signal. The controller generates the control signal based on the differential voltage signal. The optical receiver disclosed can reduce costs while ensuring signal quality.

Provided in the present invention is an automatic gain control method for a burst-mode transimpedance amplifier. A transistor is connected in parallel at either end of a feedback resistor of a transimpedance amplifier. A gate-source voltage of the transistor is controlled by detecting and then reversely amplifying an output voltage of the transimpedance amplifier. The present invention also provides a circuit implementing the method, obviates the need for support from any particular process, and is implementable using conventional components.

In optical receivers, cancelling the DC component of the incoming current is a key to increasing the receiver's effectiveness, and therefore increase the channel capacity. Ideally, the receiver includes a DC cancellation circuit for removing the DC component; however, in differential receivers an offset may be created between the output voltage components caused by the various amplifiers. Accordingly, an offset cancellation circuit is required to determine the offset and to modify the DC cancellation circuit accordingly.

An optical receiver circuit includes an input terminal receiving current signal from photodetector; a trans-impedance amplifier converting the current signal into voltage signal; an inductor having one end connected to the input terminal and another end connected to the input of the trans-impedance amplifier; a first variable resistor having a first end connected to the other end of the inductor, a second end receiving bias voltage, and a third end receiving a control signal, where the first variable resistor varies a resistance between the first end and the second end in accordance with the control signal; and a second variable resistor having a first end connected to the one end of the inductor, a second end receiving bias voltage, and a third end receiving a control signal, where the second variable resistor varies a resistance between the first end and the second end in accordance with the control signal.

The present disclosure relates to optical receivers. One example optical receiver includes an optoelectronic detector, a transimpedance amplification (TIA) circuit, a single-ended-to-differential converter, an I/O interface, and a controller. The optoelectronic detector, having bandwidth lower than required system transmission bandwidth, converts an optical signal into a current signal. The TIA circuit compensates gain for the received current signal based on a received control signal to obtain a voltage signal, where a frequency response value of the current signal within first bandwidth is greater than that within the bandwidth of the optoelectronic detector, and any frequency in the first bandwidth is not lower than an upper cut-off frequency of the optoelectronic detector. The single-ended-to-differential converter converts the voltage signal into a differential voltage signal. The I/O interface outputs the differential voltage signal. The controller generates the control signal based on the differential voltage signal.