Broadly tunable coherent mid-IR sources based on difference frequency mixing of high power laser diodes in periodically poled LiNbO 3

The recent development of both broadly tunable high power single-spatial mode laser diodes and of periodically poled LiNbO₃ (PPLN) for quasi-phasematching (QPM) has enabled the demonstration of novel laser diode based mid-IR sources based on difference frequency mixing (DFM). These sources are broadly tunable throughout the mid-IR wavelength range and offer the practical advantages of compact size, room temperature operation, and the use of inexpensive, highly reliable LiNbO₃ material. The QPM approach allows noncritical phasematching of near-IR wavelengths where high power, high reliability laser diodes have been demonstrated. The authors discuss approaches for obtaining broadly tunable mid-IR radiation by laser diode DFM in both waveguide and bulk periodically poled LiNbO₃