Abstract

The usage of compact diode-pumped nanosecond pulse length, mJ energy and kHz repetition frequency range QCW lasers seems to be very prospective for such applications as micromachinery, spectroscopy, photolithography, color laser displays, etc. Application areas could be sufficiently extended if the near IR laser output could be efficiently converted into the visible and UV spectral ranges¹ (see also Lambda Physik product data: StarLine laser) Assuming the typical Q-switched Nd:YAG laser optical conversion efficiency (at 1064 nm) of about 20 - 30% (with respect to absorbed pump power at 808 nm) one can estimate the required peak pump power incident to the gam crystal (at 300-μs pulses) being in the range of from tens to hundreds of Watt. The corresponding average pump power should be of the order of tens of Watt (at duty cycle of about 20 - 30%). Meaning thermal loading, this level is permissible for end pump layout, which is preferable from a view point of laser conversion efficiency and beam quality. The required pump power for such a laser can be provided by several high power laser diode bars (LDBs), but there is a problem of a proper beam shaping to provide circular symmetrical and tight focusing of a pump light into laser crystal. One of the ways of laser diode bar combining and shaping was reported earlier². In this paper we describe a QCW Nd.YAG laser of the IR, visible and UV ranges, using the modification of mentioned pump technique. It should be also noted that this technique is especially valuable for lasing at quasi 3-level 946-nm neodymium transition.

© 1998 IEEE