Abstract: This disclosure is concerned with digital optical circuits, including an optical astable multivibrator. In one example, an optical astable multivibrator is provided that includes a lasing semiconductor optical amplifier (LSOA), such as a VLSOA for example. The LSOA is optically coupled to a time delay component and includes a pump input, amplifier input, amplifier output, and a ballast laser output. The time delay component includes an input that is optically coupled with the ballast laser output of the LSOA. The time delay component further includes an output that is optically coupled with the amplifier input of the LSOA. The output of the LSOA is a clock signal having a periodic square waveform whose frequency is determined by the time delay component.

Abstract: A clock recovery system and related method are disclosed. One example of the clock recovery system includes an optical detector and lasing SOA that are arranged so that the optical detector detects ballast laser light emitted by the lasing SOA. The optical detector includes an output that is connected to a first input of a phase detector that includes both first and second inputs. A filter is included in the clock recovery system as well and has an input and an output, the input being connected to the output of the phase detector. Finally, this example of the clock recovery system includes an oscillator having an input and an output arranged so that the input of the oscillator is connected to the output of the filter, and the output of the oscillator is connected with the second input of the phase detector.