Accession Number : ADA626805

Title :   High Average Power Raman Conversion in Diamond: 'Eyesafe' Output and Fiber Laser Conversion

Descriptive Note : Final rept. 1 Apr 2012-31 Mar 2015


Personal Author(s) : Mildren, Richard

Full Text :

Report Date : 19 Jun 2015

Pagination or Media Count : 15

Abstract : The project increased the highest power obtained for a diamond Raman laser by 15 times and up to 0.4 kW. A continuous wave diamond laser was demonstrated that generated 108 W at 1240 nm from a 320 W Nd:YAG pump laser. A modified design generating 380 W was demonstrated using a 630 W Yb-doped fiber laser system. In each case the performance was unsaturated and limited by the available pump power. The efficiencies and brightness achieved are found to be higher than expected by current theories for thermal effects in diamond. The project also developed a diamond laser capable of providing large increases in beam quality (rom M2 = 3.5 to M2 1.1) and brightness (by 1.7 times), features that were used to demonstrate a pulsed eye-safe (1.5 m) laser based on a Nd:YAG pump with an unprecedented brightness of 540 MW/cm2/sr. What is/are the significance of the findings The results are significant in showing that diamond Raman laser technology is an efficient wavelength converter for conventional high power laser technologies including Nd doped lasers and Yb-doped fiber lasers. Diamond's power handling capability now exceeds the highest achieved for any other Raman crystal by a factor of 22 and is competitive with Raman fibers. It is highly promising for brightness enhancement of beams and for beam combining of incoherent beams based on the technique of Raman beam combination. Compared to other nonlinear conversion schemes, diamond has important advantages of large wavelength Stokes shift, wavelength range (from UV to mid-IR) and suitability for conversion a variety of temporal domains (ultrafast to cw). It is thus found to be an outstanding nonlinear optical material in terms of many important categories of high power performance.


Subject Categories : Fluidics and Fluerics

Distribution Statement : APPROVED FOR PUBLIC RELEASE