Abstract

Laser spectroscopy, long the domain of the dye laser, is experiencing a renaissance due to the development of tunable, higly coherent, external cavity diode lasers (ECDL’s). Such lasers have been used extensively as sources for precision spectroscopy experiments. Recently, ECDL’s have become commercially available, sparking interest in the development of diode laser based sensors for many industrial and process control applications. One particular class of applications involves the sensing of atoms during the growth of thin films. Many atoms have strong ground state absorption lines between 380-420 nm, a wavelength range that is fortuitously at 1/2 the output wavelength of mature GaAs based diode laser technology and accessible with either LiNbO₃, LiTaO₃, and KTP QPM-SHG waveguides. The marriage of ECDL’s and nonlinear quasi-phasematched second harmonic generation waveguide allows the generation of tunable, highly coherent radiation in the blue-UV spectral range required for atomic absorption spectoscopy. Furthermore, the low power levels and ~ 10 GHz tuning ranges required for atomic absorption spectroscopy are readily achievable with ECDL’s and QPM-SHG waveguides. Atomic absorption spectrosocpy can yield information about the deposition process and can be used to monitor and control the film growth rate. In this presentation we review the development of frequency doubled ECDL’s and applications to the material synthesis of aluminum and titanium films.

© 1996 Optical Society of America