Nam Seong Kim

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.

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.

Passively Q-Switched Diode-Pumped Continuous-Wave Nd:YAG-Cr(4+):YAG Laser with High Peak Power and High Pulse Energy.

A high peak power and high pulse energy passively Q-switched diode-pumped cw Nd:YAG laser at 1.064-mum wavelength has been demonstrated with Cr(4+):YAG crystal as the saturable absorber. The average output power of 7-12 W and pulse duration of 100-250 ns was obtained with kilohertz repetition rates. The highest peak power and pulse energy obtained were 30 kW and 3.4 mJ, respectively. All the output resulted from the TEM(00) mode with M(2) < 1.1. The thermal lensing effect of the saturable absorber was investigated, demonstrating that it played an important role in optimization of the output.

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.

Simultaneous multiple-wavelength cw lasing in laser-diode-pumped composite rods of Nd:YAG and Nd:YLF

Simultaneous multiple-wavelength cw laser operations were achieved in two types of composite laser rod composed of Nd(3+):YAG and Nd(3+):YLF crystals, which were laser diode (LD) pumped within a single virtual-point-source cavity. As much as 30 W of total output at 1064- and 1047-nm wavelengths was obtained under 150-W LD input power, with approximately 25% from the 1047-nm wavelength. Different bonding methods were compared, showing that the use of an optical adhesive is effective and presents no deterioration at low and middle power levels. Simultaneous multiple-wavelength operation at 1064- and 1053-nm wavelengths was also studied.

Output Characteristics of High-Power Continuous Wave Raman Fiber Laser at 1239 nm Using Phosphosilicate Fiber

A high-power singlemode Raman fiber laser (RFL) with maximum output power of 4.11 W and maximum power conversion efficiency of 47.40% at 1239 nm is realized using continuous wave 8.4 W Yb-doped double-clad fiber laser as a pump, 700 m phosphosilicate fiber, and a Raman cavity formed by a pair of fiber Bragg grating mirrors at 1239 nm. The output characteristics of the RFL at 1239 nm for different fiber lengths and output mirror reflectance are reported. Theoretical simulation is done to numerically optimize for fiber length and output coupler reflectivity to obtain maximum first Stokes power.

CW depolarized multiwavelength Raman fiber ring laser with over 58 channels and 50 GHz channel spacing

We demonstrated a simultaneous CW depolarized multiwavelength Raman fiber ring laser with 58 channels within 3 dB bandwidth and 50 GHz channel spacing at room temperature using fiber Fabry-Perot tunable filter (FFP-TF), 16 km dispersion-compensating fiber (DCF) and Raman pump laser diodes at 1428.2, 1445.8 and 1463.4 nm wavelengths. The output DOP was about 2.2%. By changing pump power ratio for the three wavelengths, different operating ranges could be obtained. if cavity design is optimized, more output power can be easily achieved. By selecting different pump wavelengths, different range of operation will be possible.

Numerical Modeling and Experimental Confirmation of an Efficient Phosphosilicate-Fiber Raman Laser

A model for a fiber Raman laser has been numerically solved including all the interactions between forward and backward travelling waves. The predicted numerical results are experimentally confirmed using a fiber Raman laser with P2O5-doped fiber. The maximum output power of 3.1 W at 1483.5 nm with a slope efficiency of 46% is experimentally obtained using a 300 m P2O5-doped fiber. Numerical results suggest that an output power of as much as 4 W with a slope efficiency of 57% can be achieved if the Raman cavity is optimized for the same input pump power.

Output Characteristics of P-doped Raman Fiber Laser at 1484 nm with 2.11 W Maximum Output Power Pumped by CW 1064 nm Yb-doped Double-Clad Fiber Laser

The output dependence on output reflectivity and fiber length is reported for a phosphosilicate Raman fiber laser (RFL) at the second Stokes wavelength of 1484 nm using a pump of CW 8.4 W/1064 nm Yb-doped double-clad fiber laser (DCFL) and cascaded cavities for the first and second Stokes wavelength. The output reflectivities for the second Stokes light were 15 and 50% and the lengths of the P-doped Raman fiber (PDF) were 300, 700, and 1000 m. The maximum output of 2.11 W/1484 nm was obtained using 15% output reflectivity and 700 m PDF length and the corresponding slope efficiency from the pump was 33.2%. The laser performance for the six configurations was investigated by observing the maximum output power, slope efficiency, threshold pump power, and full-width at half maximum at the second Stokes wavelength.