Low-cost 7 mW CW 355-nm diode-pumped intracavity frequency-tripled microchip laser

This 2006 publication laid the technical groundwork for Oxxius’s diode-pumped, single-frequency UV laser technology — principles still applied today in the company’s CW 355 nm laser sources for semiconductor inspection and biological analysis.

Abstract

Low noise CW milliWatt scale UV lasers are needed for many analysis applications in the semiconductor and the biological fields. Intracavity tripling has been widely used to improve the UV output power of Q-switched or modelocked lasers, but no efficient diode-pumped CW UV laser was ever reported. One of the key to success is the use of a monolithic laser structure which both eliminates the birefringence interference issue and facilitates the single frequency operation. The monolithic structure is obtained by optically contacting crystals. It does not require any alignment, reduces the manufacturing cost and improves reliability. The optimization of the amplifying medium and doubling and tripling crystals involves as many parameters as pump absorption, thermal lens, cavity length, 1064 nm mode size, walk-off, acceptance angles, polarizations, phases… The interplay between these parameters will be …