Properties of 20-Hz eye-safe cascade Raman laser with Ba(NO_3)_2 crystal

摘要

Recently, lasers operating in the eye-safe wavelength around 1.5mum have found increasing demand in the laser radar (LIDAR). Raman laser pumped by well established lasers such as Nd: YAG lasers is a favorable candidate with such characteristics at high repetition rate, narrow linewidth, and good beam quality.~1 As the Raman conversion medium, a Ba(NO_3)_2 crystal has attracted much attention because of its high gain and strong mechanical properties.~2 Laser output in the eye-safe wavelength region can be obtained with the Ba (NO_3)_2 crystal either in a first Stokes line pumped by 1.3 mum Nd: YAG laser~2, or in a third Stokes line pumped by 1.06 mum Nd: YAG laser~3. When the Raman crystal exhibits substantial residual absorption in th pump or Stokes wavelength, these solid-state Raman lasers require some thermal management to scale up to high average power systems such as in LIDAR. Hence, we experimentally studied the thermal characteristics of the Ba (NO_3)_2 cascade Raman conversion process.