An optical device comprises a light input, a light modulating means and a light output. The optical device further comprises an optical amplification device arranged to amplify light travelling between said light modulating means and said output. The optical amplification device comprises first and second serially connected post SOA (Semiconductor Optical Amplifier) units, each comprising at least one respective serially connected post SOA segment, which device is arranged to vary a light amplification by varying respective SOA bias voltages across said post SOA segments. A total SOA length of the first post SOA unit is relatively longer than a total SOA length of the second post SOA unit, which is relatively shorter. The optical device is arranged to, during operation using a particular operation program, always keep respective SOA bias voltages across each of the post SOA segments of the first post SOA unit at +0.5 V or more.

A connector which serves as an optical transmitter in accordance with an embodiment of the present invention includes: a transmitting circuit configured to convert a data signal into an electric current signal, the data signal being a three-valued; and an LD configured to convert the electric current signal into an optical signal. The transmitting circuit detects, as an IDLE interval, an interval during which the data signal falls within a predetermined range that is between a high level and a low level. The transmitting circuit controls, during the IDLE interval, the electric current signal to be not greater than a threshold electric current of the LD.

A method for physical random number generation includes the steps of: modulating the gain of a vertical-cavity surface-emitting laser periodically from the lower threshold to the upper threshold and back; maintaining the gain per round trip positive for a longer period than the round trip time of the cavity; maintaining the net gain per round trip negative for a longer period than the round trip time of the cavity, in order to create optical pulses of random amplitude; detecting the optical pulses; converting the optical pulses into electrical analog pulses; and digitising the electrical analog pulses into random numbers.

The DML driver includes: a post driver which supplies a driving current to the LD; and a pre-driver which drives the post driver in response to a modulated signal. The pre-driver has a transistor, a peaking inductor, a peaking inductor, a group delay inhibition inductor, and a peaking capacitor.

An embodiment circuit includes a diode having a first terminal coupled to a first reference voltage; a first controllable switch coupled between a second terminal of the diode and a second reference voltage; and a capacitive element having a first terminal coupled to the first reference voltage and a second terminal controllably coupled to the second terminal of the diode.

A connector which serves as an optical transmitter in accordance with an embodiment of the present invention includes: a transmitting circuit configured to convert a data signal into an electric current signal, the data signal being a three-valued; and an LD configured to convert the electric current signal into an optical signal. The transmitting circuit detects, as an IDLE interval, an interval during which the data signal falls within a predetermined range that is between a high level and a low level. The transmitting circuit controls, during the IDLE interval, the electric current signal to be not greater than a threshold electric current of the LD.

An embodiment circuit includes a diode having a first terminal coupled to a first reference voltage; a first controllable switch coupled between a second terminal of the diode and a second reference voltage; and a capacitive element having a first terminal coupled to the first reference voltage and a second terminal controllably coupled to the second terminal of the diode.

The disclosure provides an optical module, including a laser, the laser including a light emitting region and a modulation region, and light emitted by the light emitting region emitting toward the modulation region; a first driver circuit, the first driver circuit being connected to the light emitting region, so that the light emitting region emits light with adjusted optical power; and a second driver circuit, the second driver circuit being connected to the modulation region, so that the modulation region changes the optical power of the light emitted from the light emitting region.

Various embodiments of an optical transmitter and a method of operating an optical transmitter are disclosed. In one embodiment, the optical transmitter includes a laser and a laser driver configured to drive the laser using either a voltage driving topology (CDT) or a current-driving topology (VDT). The laser driver includes a switch that is configured to switch between the CDT and the CDT based on an operating frequency of the optical transmitter.

The present disclosure relates to the field of optical communication, particularly to an optical module. An optical module according to embodiments of the disclosure includes: a laser device including an emission region, and a modulation region to which light emitted by the emission region is transmitted; a bias circuit connected with the emission region, configured to drive the emission region to emit light at stable optical power; a modulation circuit connected with the modulation region, configured to drive the modulation region, so that the modulation region varies the optical power of the light emitted from the emission region; and a semiconductor optical amplifier configured to receive the light from the modulation region, and to vary the optical power of the light.