INJECTION-LOCKING OF CAVITY-DUMPED FLASHLAMP PUMPED DYE LASERS (HIGH POWER, QUANTUM ELECTRONICS, DESIGN, AMPLIFIER)

Injection-locking has long been recognized as an effective method of externally controlling the spectral characteristics of a laser. This technique has been employed primarily in applications where high energy yet narrow-linewidth pulsed laser emision is required. In pulsed injection-locked systems, line-narrowing is accomplished by injecting a low energy, narrow-linewidth pulse into a high power laser oscillator. If injection occurs prior to the onset of lasing in the high power oscillator, a "head-start" is given to that radiation which is within the spectral band of the injected signal. If this "head-start" is substantial enough, lasing is initiated at the wavelength and the linewidth of the injected signal. In the work presented here, this technique was applied to a cavity-dumped coaxial flashlamp pumped dye laser in an effort to obtain nanosecond duration pulses which have both high energy and narrow-linewidth. In the absence of an injected laser pulse, the cavity-dumped dye laser was capable of generating high energy (('(TURN))60mJ) nanosecond duration output pulses. These pulses, however, had a fixed center wavelength and were extremely broad-band (('(TURN))6nm FWHM). Experimental investigations were performed to determine if the spectral properties of these outputs could be improved through the use of injection-locking techniques. A parametric study to determine the specific conditions under which the laser could be injection-locked was also carried out. Significant linewidth reduction (to >0.0015nm) of the outputs was obtained through injection-locking but only at wavelengths near the peak lasing wavelength of the dye. It was found, however, that, by inserting weakly dispersive tuning elements in the laser cavity, these narrow-linewidth outputs could be obtained over a wide (24nm) tuning range. Since the weakly dispersive elements had low insertion losses, the tunability of the output was obtained without sacrificing output pulse energy.