Laser diode-pumped Tm, Ho:YLF single-frequency laser

Abstract To attain high efficiency, miniature and stable laser, we take Tm, Ho:YLF(Tm 6%; Ho 0.4%) microchip pumped by diode laser as the seed laser. Short resonant cavity which owns broad free spectral range is useful to select single-frequency. The microchip is 0.9 mm. Both end faces are coated. The microchip itself is the oscillate cavity. It is placed in the Dewar bottle. The bottle is filled with liquid nitrogen to keep the temperature at 77 K, which enhances the stability of output power. Self-beat of fiber delay method is used to measure the short-term frequency stability. It indicates that the short term stability is about 2.6 kHz/μs. And by using the oscilloscope, the long term stability is estimated at 35 MHz. Single-mode output laser with the wavelength of 2.067 μm is obtained, and its bandwidth is less than 40 MHz. The beam quality is about 1.082 which is measured by the knife-edge method. The maximal output power is up to 32.8 mW. The slope efficiency is 25.2%, and the optical-optical efficiency is 23.8%. The instability of the output power is less than 1%.