Diode-pumped optical parametric oscillators

Summary form only given. We give an overview on selected examples of diode pumped OPOs. We report on diode pumped triply and doubly-resonant CW OPOs with low threshold powers in the range of about 100 /spl mu/W to 100 mW. Such OPOs are of interest, e.g. for a phase-coherent all-optical frequency division, such as in a self-phase-locked degenerate OPO. We present an all-optical frequency-by-3 divider, where a two-section PPLN crystal enables operation of the OPO simultaneously with intracavity frequency doubling of the idler wave, for an optical phase-locking of the signal wave at twice the idler frequency. The OPO converts the 812 nm wavelength of an AlGaAs diode laser into a signal wavelength of 1218 nm and an idler wavelength of 2436 nm, where these wavelengths are exact (integer) multiples of the pump wavelength. At higher diode pump powers, such as provided by MOPA systems, it becomes possible to operate singly-resonant CW-OPOs (SROs) well above threshold. We describe a signal-resonant ring-cavity SRO which is based on PPLN and is pumped with an InGaAs diode MOPA system at wavelengths around 925 nm. The SRO shows a threshold of 1.6 W whereas the single-frequency maximum 2.07 /spl mu/m idler output power is 0.5 W at a pump power of 2.5 W. Coarse and quick tuning across hundreds of nanometers is achieved by tuning the diode laser over an interval of 1.5 nm. More than 50 GHz continuous (mode-hop free) tuning of the idler wave is possible by continuous tuning of the diode laser wavelength.