Integrated OPGs and OPOs for the Mid-Infrared Spectral Range

OPGs and OPOs are attractive devices to generate tuneable coherent radiation in a broad wavelength range for many applications mainly in spectroscopy, environmental sensing and process monitoring. Particularly Ti-diffused waveguides in periodically poled Lithium Niobate (PPLN) proved to be most attractive devices to develop OPGs and OPOs for the mid infrared (MIR) wavelength range due to their very low propagation losses (~0.03 dB/cm). In this work generation of tunable radiation in the wavelength range between 2 and 4 µm is discussed. High power OPGs and OPOs, starting with device fabrication, characterization, experimental setup and results, are presented in continuous and pulsed mode of operation. For the first time mode field distribution and generation of MIR pulses are comprehensively characterized theoretically and experimentally. Bent waveguides of the length up to 20 cm for the MIR spectral range are also discussed. Comparison with results of other groups and possible further steps and application examples are presented.