Diode laser frequency doubling using nonlinear crystal resonator with electronic resonance locking

摘要

A semiconductor laser apparatus comprises a DC power supply coupled with an RF source which generates a low-amplitude RF current which is injected into a diode laser source. An optical beam shaping system processes the laser beam and directs it to a nonlinear resonator having a plurality of longitudinal resonator frequencies with a fundamental spatial mode. The nonlinear resonator uses a phase-matched, second harmonic generation (SHG) process to generate a second laser beam by frequency doubling the central carrier frequency of the diode laser source, and further reflects a portion of the incident laser beam to an electronic resonance locking system. The electronic resonance locking system has a photodetector to receive the reflected portion of the incident beam from the resonator and generates an RF signal arising from the difference in phase shifts or amplitude losses experienced by the RF sidebands. An RF mixer receives the RF signal from the photodetector and an input from the RF source to generate an error signal as a feedback signal which is supplied to the diode laser source for tuning the laser injection current.