Low noise CW UV lasers are needed for applications in bioinstrumentation (cell sorting, cytometry...) and
semiconductors (wafer inspection, micromachining ...). We have recently demonstrated that such laser sources
can be obtained with diode pumped solid state (DPSS) architectures. One key to success was the quasimonolithic
structure of the laser. The advantages of quasi-monolithic DPSS lasers for UV generation are
simplicity of design, compactness, efficiency and thus low power requirements and limited heating.
In this paper, we present for the first time a long term characterization of the diode pumped CW 355 nm laser.
The interplay between pump absorption, cavity length, 1064 mode size, walk-off angle, acceptance angle has
been optimized. In our experiments, the temperature of each element of the laser was controlled and UV power,
noise and spectra were monitored versus these temperatures. At 2.5 W pump power, low noise UV power
beyond 30 mW was measured on most samples built. At a reduced pump power of 1.65 W, all lasers were
operating at 10 to 15 mW and could be maintained at 10 mW over days. The noise level remained below the 1%
rms level. More long-term measurements will be presented at the conference.