Electronically tunable fiber-feedback optical parametric oscillator with intracavity echelle grating stretcher

We introduce the concept of a gain-switched diode-based fiber-feedback optical parametric oscillator with an intracavity echelle grating stretcher for time-dispersion wavelength tuning. Our approach enables four different tuning ranges corresponding to different grating orders in the stretcher. Within each tuning range, the wavelength is adjusted electronically by varying the pump laser's repetition rate. This approach maintains entirely static optics while delivering a narrow linewidth of less than 1 nm and a wavelength reproducibility of 2 pm. Time-dispersion wavelength tuning by a static echelle grating stretcher with grating-order multiplexing combines high repeatability, stability, and electronic tuning, and expands the tuning range by the number of grating orders. This concept can be transferred to other grating types and spectral ranges and is ideal for applications in infrared narrowband AM/WM spectroscopy.