Abstract

Coherent ultraviolet light has many applications in science and industry. Although excimer lasers conveniently produce deep UV light, they operate only in pulsed mode. Different applications areas can be developed when a cw coherent UV source becomes available. Nonlinear optical frequency conversion techniques will become important to obtain the deep UV light. Recent advancements in nonlinear optical materials and laser techniques make frequency doubling of blue-green cw lasers more realistic. Although the effective optical nonlinearity is not as large as other crystals usable in the doubling of near-infrared fundamental light, beta barium borate (BBO) crystal is the best among the nonlinear materials for UV generation because of its wide phasematching region down to 205-nm by SHG, low optical loss, and durability.¹ In fact, the low nonlinear coefficient can be compensated by its low absorption through an effective enhancement of the fundamental power by using an optical resonator.

© 1993 Optical Society of America