Abstract

We present theoretical calculations of an optical parametric oscillator (OPO) containing, in addition to the OPO crystal, a crystal for intracavity sum-frequency generation (SFG). The latter crystal combines light at the pump frequency ω_p with light at the OPO signal frequency ω_s to produce the desired frequency ω_d= ω_p+ ω_s. Only the frequency ω_s oscillates in the cavity. This system is modeled in the plane-wave approximation for both spatial orderings of the crystals. The pump power is ultimately converted to the desired radiation, to idler radiation of frequency ω_i =2ω_p – ω_d, and to cavity losses at frequency ω_s. Since the ω_i and ω_d radiation grows from zero on each pass, changes in the cavity length do not produce interference effects. The choice of crystal for the OPO is limited by the requirement that this crystal transmit the long-wavelength idler. With proper choice of design parameters, little pump power remains unconverted by the two crystals over an extended range of the incident pump intensity. In steady-state operation the ratio η of the photon flux emitted at ω_d to the photon flux incident at ω_p can be nearly 0.5.

© 1992 Optical Society of America