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: An optical multiplexer is provided that includes a reconfigurable switching fabric with a number of inputs and outputs. In addition, the reconfigurable switching fabric employs VLSOAs that facilitate at least partial reconfiguration of the switching fabric by serving as switches to add, drop or pass-through one or more optical signals received at the inputs of the reconfigurable switching fabric. In some cases, one or more of the VLSOAs also serve to amplify one or more optical signals so as to compensate for losses that may be experienced by the signal in transit through the switching fabric, or elsewhere. Finally, this example of the optical multiplexer includes a wavelength division multiplexer coupled to the reconfigurable switching fabric and configured to multiplex at least some of the optical signals received from outputs of the reconfigurable switching fabric.