Diode Laser Phase Conjugation 03 Fs 030 Final Report

Download or read book Diode-Laser Phase Conjugation 03-FS-030 Final Report written by and published by . This book was released on 2005 with total page 2 pages. Available in PDF, EPUB and Kindle. Book excerpt: Arrays of lasers are often considered when a need exists to increase laser optical output power, for a variety of purposes. Similarly, individual semiconductor laser-diodes, generating 0.01-1.0 W each, are commonly placed in arrays in order to increase total optical power onto targeted objects. Examples of such usage are diode-laser pump arrays for solid-slab heat-capacity lasers, laser arrays for heat-treating materials, and arrays for efficient solid state laser systems. The commercial and defense communities also use such arrays for many applications from laser range-finders, laser designators, to laser machining systems, etc. However, the arraying process does not automatically increase ''focusable'' light on target (i.e., intensity/steradian). For those applications requiring the highest focusability, it is necessary that the collective output beam from arrays of individual lasers be phase-coherent. Under this condition, the individual laser-element optical outputs are ''fused together'' into a larger area, phase coherent (i.e., all wavefronts are ''in step''), high-power combined beam. The process of joining multiple laser beams together to produce a single coherent wave, is in general very difficult and seldom accomplished. Thus joining together many hundreds to thousands of beams from individual laser-diodes, in large arrays, is still an unsolved problem. There are 2 major reasons for this. Firstly, the phase of each output laser beam (i.e. the wave-fronts) from each laser diode often fluctuates within nanosecond time periods, making a control loop with sufficient bandwidth difficult to build. In fact, phase fluctuations (related to laser linewidth) limit the size of an extended system of arrayed diodes because of speed-of-light restrictions on information flow. Secondly, the output power per prior laser diode has been low (1W,) so that the size, expense, and complexity of control systems for correcting a multitude of output phases of the individual diode lasers in a large array, become prohibitive. Recently, we have been considering ways to use new diode geometries and 4-wave mixing/phase-conjugation technologies to enable large arrays of semiconductor lasers to be phased together to produce large-output-power laser systems, with good beam quality. If the ideas hold up, arrays of 100 to 1 million laser elements might produce 100 W to> 1 Megawatt laser beams. Such systems can have many defense and commercial applications.