A method of optical signal amplification. Incident photons are received at a photodetector including a doped semiconductor biased by a power source. The photons generate a change in a reflective property, refractive index, or electrical conductivity of the doped semiconductor. For the change in reflective property or refractive index, a first optical signal is reflected off the photodetector to provide a reflected beam, or the photodetector includes a reverse biased semiconductor junction including the doped semiconductor within a laser resonator including a laser medium, wherein a second optical signal is emitted. For the change in electrical conductivity the photodetector includes a reversed biased semiconductor junction that is within an electrical circuit along with an electrically driven light emitting device, where a drive current provided to the light emitting device increases as the electrical conductivity of the photodetector decreases, and the light emitting device emits a third optical signal.