Mahendra Prabhu

Highly efficient 2% Nd:yttrium aluminum garnet ceramic laser

A highly efficient diode-laser end-pumped polycrystalline 2% Nd:yttrium aluminum garnet (YAG) ceramics laser that is comparable in efficiency with Nd:YAG single crystal laser has been developed. With 883 mW pumping, 465-mW-cw laser output at 1064 nm has been obtained corresponding to an optical-to-optical efficiency of 52.7%. The laser threshold is only 30 mW with R=97% output coupler.

72 W Nd:Y3Al5O12 ceramic laser

A high-power continuous-wave polycrystalline 1% Nd:Y{sub 3}Al{sub 5}O{sub 12} (Nd:YAG) ceramic rod laser was demonstrated. With 290 W/808 nm laser diode pumping, cw laser output of 72 W was obtained at 1064 nm. The optical-to-optical conversion efficiency is 24.8%. Thermally induced birefringence properties of Nd:YAG ceramic was also investigated. {copyright} 2001 American Institute of Physics.A high-power continuous-wave polycrystalline 1% Nd:Y3Al5O12 (Nd:YAG) ceramic rod laser was demonstrated. With 290 W/808 nm laser diode pumping, cw laser output of 72 W was obtained at 1064 nm. The optical-to-optical conversion efficiency is 24.8%. Thermally induced birefringence properties of Nd:YAG ceramic was also investigated.

High-Power Nd:Y3Al5O12 Ceramic Laser

High power CW (continuous wave) polycrystalline Nd:Y3Al5O12 (Nd:YAG) ceramic rod laser was demonstrated for the first time. The maximum output power of 31 W with a 18.8% slope efficiency was obtained at 1064 nm using 214.5 W/808 nm laser diode pumping.

Ultra-Broadband CW Supercontinuum Generation Centered at 1483.4 nm from Brillouin/Raman Fiber Laser

About 100 nm CW supercontinuum centered at 1483.4 nm was generated from Brillouin/Raman fiber laser (BRFL). The BRFL consists of a Raman cavity with 700 m of phosphosilicate fiber (PDF) and pairs of fiber Bragg grating (FBG) mirrors and a Brillouin cavity with the PDF, 500 m of flexcor-1060 fiber, and output FBG mirrors. With 8.4 W/1064 nm Yb-doped double-clad fiber laser as pump and 50% feedback FBG mirror at end of BRFL, output power of over 1 W with 100 nm bandwidth centered at 1483.4 nm and weak 0.11 nm spectral modulation were observed.

1239/1484 nm cascaded phosphosilicate Raman fiber laser with CW output power of 1.36 W at 1484 nm pumped by CW Yb-doped double-clad fiber laser at 1064 nm and spectral continuum generation

CW 1.36 W/1484 nm Raman fiber laser is obtained using 8.4 W/1064 nm Yb-doped double-clad fiber laser as a pump, 1 km phosphosilicate fiber, and cascaded cavities with two pairs of fiber Bragg grating mirrors for 1239 nm and 1484 nm. We observed that there is a three-step process for the power transfer from the pump to the second Stokes powers. In addition, a 100 nm spectral continuum was obtained by connecting the 1484 nm output to single-mode fiber.

Highly Efficient Nd:Y3Al5O12 Ceramic Laser

A highly efficient laser diode end-pumped polycrystalline 1% Nd:Y3Al5O12 (Nd:YAG) ceramic laser has been developed. It is comparable to a Nd:YAG single crystal laser in terms of efficiency. With 883 mW pumping, CW laser output of 499 mW at 1064 nm has been obtained, which corresponds to an optical-to-optical efficiency of 56.5%. The threshold is only 22 mW for a R=97% output coupler. Passively Q-switched operation has also been demonstrated using a Cr4+:YAG single crystal as a saturable absorber.

Efficient double-clad thulium-doped fiber laser with a ring cavity

We have constructed a novel ring cavity for a double-clad thulium-doped fiber laser, by placing the fibers 45 degrees angle-polished output end before the input end and relaunching the pump and the laser power into the fiber. This design can reduce reabsorption by using short fibers without loss of pump efficiency. The dependence of the lasers performance on the fibers length and the output couplers reflectivity is investigated experimentally and theoretically. With an 80-cm-long fiber, 2.7-W single-mode continuous-wave output is generated for 11.5 W of launched pump power.

Numerical analysis and experimental results of output performance for Nd-doped double-clad fiber lasers

Numerical analysis is investigated for the high-power double-clad fiber lasers and experimental results using different microscope objectives for focusing into a Nd-doped rectangular double-clad fiber also performed. The numerical analysis includes dependence of output power on output mirror reflectivity, absorbed pump power, loss, and fiber length and pump power distribution for the cases of one-end and two-end pumps with 20 dBrkm loss. Calculated conversion efficiencies are 76.36%, 69.73%, and 63.84% for lossless, two-end pump, and one-end pump fiber lasers, respectively. Slope efficiencies from absorbed pump powerroutput powers measured using microscope objectives are 16.8%r182 mW, 53.8%r351 mW, 24.9%r1240 mW, and 13.9%r649 mW for magnifications of 5= ,1 0= ,2 0= , and 40 = , respectively. q 2000 Elsevier Science B.V. All rights reserved.

1212 nm pumping of 2 μm Tm–Ho-codoped silica fiber laser

A Tm–Ho-codoped silica fiber laser pumped by a third-stokes Raman Fiber Laser at 1212 nm is demonstrated. For the 30-cm-long Tm–Ho-codoped fiber, a 400 mW output power is obtained at a wavelength of 1790 nm due to the laser emission from the Tm3+ ions. For the 270-cm-long Tm–Ho-codoped fiber, a 450 mW output power is obtained at 1970 nm due to the laser emission from Ho3+ ions.

Simultaneous two-color CW Raman fiber laser with maximum output power of 1.05 W/1239 nm and 0.95 W/1484 nm using phosphosilicate fiber

High-power two-color CW Raman fiber laser is obtained with simultaneous outputs at 1239 nm and 1484 nm which uses CW 8.4 W Yb-doped double-clad fiber laser at 1064 nm as a pump, phosphosilicate fiber, and cascaded cavities consisting of two pairs of fiber Bragg grating mirrors. Maximum output powers are 1.05 W at 1239 nm and 0.95 W at 1484 nm with 700 m of phosphosilicate fiber. The output characteristics of this laser for different fiber lengths are reported.