We describe a simple and passive nanosecond-long laser-pulse stretcher using multiple optical ring cavities. We present a model of the pulse-stretching process for an arbitrary number of optical ring cavities. This new model explicitly includes the effects of cavity delay time, beam-splitter reflectivity, total number of optical cavities, and describes the effects of spatial profile sensitivity. Using the model, we optimize the design of a pulse stretcher for use in a spontaneous Raman-scattering excitation system that avoids laser-induced plasma spark problems. From the optimized design, we then experimentally demonstrate and verify the model with a three-cavity pulse-stretcher system that converts a 1000-mJ, 8.4-ns-long input laser pulse into an approximately 75-ns-long (FWHM) output laser pulse with a peak power reduction of 0.10× and an 83% efficiency.
© 2002 Optical Society of America
(140.0140) Lasers and laser optics : Lasers and laser optics
(140.3550) Lasers and laser optics : Lasers, Raman
(220.4830) Optical design and fabrication : Systems design
(320.4240) Ultrafast optics : Nanosecond phenomena
(320.5540) Ultrafast optics : Pulse shaping
Jun Kojima and Quang-Viet Nguyen, "Laser Pulse-Stretching with Multiple Optical Ring Cavities," Appl. Opt. 41, 6360-6370 (2002)