Broadly Tunable, Narrow Linewidth Dye Laser Emission in the near Infrared*

The generation of broadly tunable, narrow linewidth. high power radiation in the near infrared is important for a number of scientific applications. The infrared radiation may be utilized as a spectroscopic source or in laser-matter interactions that require a high power. wavelength tunable light source. Frequency doubling of the near infrared radiation leads to a tunable source of high spectral brightness in the near ultraviolet and visible blue [I] Also, difference frequency experiments can be performed which involve mixing tunable near infrared radiation with a fixed frequency laser source to generate tunable mid-infrared radiation [Z-4] We wish to report the operating characteristics of an efficient, narrow bandwidth infrared dye laser source This source employs polymethine dyes [S] and is capable of a wide tuning range for a single dye, previously reported only for dye lasers operating in the visible spectrum. Broadband infrared dye lasers reported to date produce peak powers of about 1 MW in a IOO300 .& bandwidth for a 70 MW laser pump. Upon the introduction of wavelength dispersive elements to the dye laser cavity, narrowband infrared output is obtained with reported tuning ranges of 100-500 a for a single dye [ 1 m-61