Optics and Photonics Journal, 2013, 3, 51-62 http://dx.doi.org/10.4236/opj.2013.31009 Published Online March 2013 (http://www.scirp.org/journal/opj) Diode Pumped High Peak Power Quasi Q-Switched and Passively Q-Switched Nd:YVO 4 Lasers at 1064 nm and 532 nm Using Cr:YAG and KTP Crystals Ashraf F. El-Sherif 1,2 , Mahmoud M. Talat 3 1 Townes Laser Institute, CREOL College of Optics and Photonics, University of Central Florida, Orlando, USA 2 Laser Photonics Research Group, Engineering Physics Department, Military Technical College, Cairo, Egypt 3 Military Technical Institute, Cairo, Egypt Email: ashraf.alsharif@staff.aast.edu, ashraf.elsherif@creol.ucf.edu Received November 6, 2012; revised December 7, 2012; accepted December 14, 2012 ABSTRACT Diode end-pumped solid-state lasers have the potential to yield high quality laser beams with high efficiency for laser range finding and warning receiver applications as well as day and night military laser designation systems. In this pa- per we presents theoretical calculations using Advanced Dynamics Professional LASCAD software and experimental studies for a high power pigtailed fiber diode laser module of 8 W operating at 808 nm with a specially designed high efficiency cooling system, end pumped high-efficiency Nd:YVO 4 laser of 3 × 3 × 10 mm rod and overall cavity length of 44 mm. To the best of our knowledge a self Q-switching effects was generated in Nd:YVO 4 laser by changing the cavity dimensions and the position of the intracavity KTP crystal at certain regime of operation for the first time, in which the cavity length is reduced to be 30 mm and the distance between Nd:YVO 4 rod and KTP crystal is only 1mm. Self Q-switched laser pulse at 532 nm with high peak power of 96 W, pulse width of 88 ns at FWHM and repetition rate of 400 kHz was achieved. Experimental studies of a passive Q-switched Nd:YVO 4 laser using Cr:YAG crystal with three different transmissions of 30%, 40% and 70% were investigated. Passive Q-switched laser pulse at 1064 nm and narrow line width of less than 1.5 nm with highest peak power of nearly 18 kW, short pulse width of less than 4 ns at FWHM and higher repetition rate of 45 kHz using Cr:YAG with transmission of 30% was achieved for the first time. Keywords: High Power Diode Laser; High Power Nd:YVO 4 Laser; Cr:YAG Saturable Absorber Mirror; Passive Q-Switching; KTP Crystal; Self Q-Switching; Special Cooling System 1. Introduction Three decades of solid-state laser research have contri- buted to the development of a unique family of powerful photonic tools. Solid-state laser media, such as neodym- ium-doped crystal, was used in applications like laser fusion, material processing, optical communications, prod- uct marking, remote sensing and surgery [1,2]. Optical pumping using a semiconductor laser diode instead of conventional flash lamp provides more efficient, reliable, stable laser output, rigid and compact for different of military applications. In contrast to flash lamp pumping (the conventional method for generating a population in- version in solid-state gain media); excitation using a monochromatic and spatially coherent laser pump source offers lower threshold, higher output efficiency, reduc- tion of thermal loading and improving mode quality. Semiconductor lasers were in their formative years, pro- viding low powers (few mW); they were not competitive with flash lamps, until efficient high power AlGaAs laser diode became available in the mid-1980’s [3,4]. Today, reliable one and two-dimensional laser diode arrays are commercially available with continuous-wave and quasi- CW peak powers up to 100 W and 10 kW respectively [5]. Simulation using LASCAD tool package provides complex engineering methods; developed on purpose for ease of operation. Great attention has been paid to high peak power all-solid-state blue-green laser for some ap- plications, such as medical applications, spectroscopy, display, optical data storage, undersea detection and com- munications and day/night military designation systems. The intracavity frequency doubling of a CW laser-di- ode-pumped Q-switched Nd-doped solid-state laser is one of the most efficient ways to generate these wave- lengths. Furthermore, laser-diode-pumped all solid-state laser device has high efficiency, small volume and com- Copyright © 2013 SciRes. OPJ