Reconfigurable all-optical activation functions having normalized output power

An optical device, comprising:

• a Mach-Zehnder interferometer (MZI) comprising a first branch and a second branch;
• a microring resonator (MRR) coupled to the first branch;
• a first phase-shift mechanism coupled to the MRR configured to tune a resonance frequency of the MRR;
• a second phase-shift mechanism coupled to the second branch, the second phase-shift mechanism configured to control biases of the MZI to tune optical interference between optical signals propagating in the first and second branches;
• and
• an optical amplification mechanism coupled to an output of the MZI and configured to add optical gain to an output of the MZI, wherein the optical amplification mechanism comprises:
• a cathode formed on a waveguide coupled to the output of the interferometer;
• a mesa structure formed on the cathode, the mesa structure comprising an optically active medium;
• and
• an anode formed on the mesa structure,
• wherein the cathode is formed between the waveguide and the anode, and
• wherein the optically active medium emits light based on a bias applied between the cathode and the anode.

A method for operating a nonlinear activation device, the method comprising:

• adjusting a first bias of an interferometer included in the nonlinear activation device by controlling a first phase-shift mechanism coupled to a first branch of the interferometer to tune a phase difference between the first branch and a second branch of the interferometer;
• adjusting a second bias of a resonator cavity, coupled to a second branch of the interferometer, such that the nonlinear activation device functions at approximately a resonance frequency of the resonator cavity by controlling a second phase-shift mechanism coupled to the resonator cavity;
• tuning a voltage bias applied to a semiconductor optical amplifier coupled to an output of the interferometer based on the phase difference between the first branch and the second branch of the interferometer to tune an amplitude of the output of the interferometer,
• wherein the first and second bias are controlled to achieve a desired activation function;
• and
• switching between a first activation function and the desired activation function by tuning one or more of the first and second bias,
• wherein the voltage bias applied to the semiconductor optical amplifier is tuned so that an amplitude of an optical power output by the semiconductor optical amplifier for the desired activation function is approximately equal to an amplitude of an optical power output by the semiconductor optical amplifier for the first activation function.