An
optical parametric oscillator (OPO) is described that efficiently converts a near-
infrared laser beam to tunable mid-
infrared wavelength output. In some embodiments, the OPO includes an optical
resonator containing a nonlinear
crystal, such as periodically-poled
lithium niobate. The OPO is pumped by a continuous-wave
fiber-
laser source having a low-power oscillator and a high-power
amplifier, or using just a power oscillator). The
fiber oscillator produces a single-frequency output defined by a distributed-feedback (DFB) structure of the
fiber. The DFB-fiber-
laser output is amplified to a pump level consistent with exceeding an oscillation threshold in the OPO in which only one of two generated
waves (“
signal” and “idler”) is resonant within the
optical cavity. This pump source provides the capability to tune the DFB
fiber laser by straining the fiber (using an attached piezoelectric element or by other means) that allows the OPO to be continuously tuned over substantial ranges, enabling rapid, wide continuous tuning of the OPO output frequency or frequencies.