Tunable midwave infrared generation with an optical parametric oscillators and difference frequency generation

Continuous tunable mid IR generation is analyzed by difference frequency generation (DFG) in an optical parametric oscillator (OPO). The periodically poled KTiOPO4(PPKTP) crystals are used for DFG of position tuning, temperature tuning and noncollinear angle tuning. Using position tuning and temperature tuning of OPO, signal wavelength tuning of DFG is also analyzed. The tuning curves, the tolerances and the walk-off angles of these tuning methods are given. The noncollinear angle tuning in combination with the temperature tuning is a better tuning method. Its advantages include wider tunable range and rapid tunability.