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Narrow Spectral line width of high power lasers

High power laser diodes have been developed for applications including solid-state laser pumping, fiber laser pumping, and material processing. The spectral bandwidth of high power diodes typically spread over the range of 3-5 nm. Narrow emission spectrum in the range of 0.1-0.5 nm and a smaller wavelength tolerance can be extremely beneficial for special applications such as the spin-exchange optical pumping (SEOP), which is of great importance in the field of nuclear physics , atomic physics , laser cooling and neutron scattering. A variety of external cavity techniques has been developed to narrow the spectral line width of high power diode lasers. Two types of gratings are used to form the external cavity. The diffraction grating external cavity provides a large tunable range of the center wavelength ~10 nm. Meanwhile, the volume holographic grating (VHG) external cavity has a smaller footprint with a limited tunable center wavelength range of <0.5 nm. The resonant wavelength of a VHG can be precisely tuned with temperature control. Using a thick VHG (14-18 mm) one can narrow the spectral line width down to a few GHz (7-10 GHz) with output power exceeding tens of watts.
Due to the low beam quality of high power broad-area laser diodes, it is difficult to effectively couple the laser power into a multi-mode fiber without special beam shaping treatment. High power, narrow spectral line width diode lasers are useful for optical pumping of alkali metal vapors. High power, spectral narrowed lasers with good stability are the key to the success of SEOP. However, such laser diode arrays are not the best choice for the high-efficiency optical pumping applications.
Achieving the narrow spectral linewidth that is required for a long coherence length makes for complicated and expensive lasers, although complexity and size can be somewhat reduced by going with a semiconductor laser design. Now, Optromix single frequency high power fiber Laser Irybus-SF-1030-X series offers a wide-range thermal wavelength tuning and optional active wavelength control. Irybus-SF-1030-X is a single frequency high power low noise 1030 nm – 1100 nm Yb-doped fiber laser. Its key advantage is an ultra narrow line width (<100 kHz) based on a longitudinal single mode. Irybus-SF-1030-X comes with a piezoelectric tuning, internal and external wavelength modulations at kHz bandwidth for locking purposes.