Independently tunable, dual-wavelength source based on two-crystal, continuous-wave, singly resonant optical parametric oscillator

摘要

Independently tunable, coherent dual-wavelength light sources are of great interest for applications including spectroscopy, short- and long-wavelength generation using nonlinear frequency conversion and many more. While optical parametric oscillators (OPOs) are now established as versatile and practical sources of widely tunable radiation, the generation of a signal-idler pair of truly arbitrary wavelength pairs is not possible due to constrained phase-matching (kp=ks+ki) and energy conservation (ωp=ωs+ωi). Although operating OPO near degeneracy can results a pair of signal-idler with concomitant difficulties [1], the energy coupling between the signal and idler makes it impossible to generate wavelength pairs with truly arbitrary values. Here, we present a novel and generic approach for the generation of two truly independently tunable wavelengths, which are unbound by energy conservation and can be independently controlled to provide any arbitrary value using a simple design based on a compact four mirror ring-cavity cw OPO. Moreover, both wavelengths are resonant within the same cavity, thus providing high circulating intensities at the two wavelengths, and the beams can have the same power. Such a novel system can be used to generate tunable THz radiation down to 0.55 THz.