Arun Kumar Sridharan

Analysis of the scalability of diffraction-limited fiber lasers and amplifiers to high average power

We analyze the scalability of diffraction-limited fiber lasers considering thermal, non-linear, damage and pump coupling limits as well as fiber mode field diameter (MFD) restrictions. We derive new general relationships based upon practical considerations. Our analysis shows that if the fibers MFD could be increased arbitrarily, 36 kW of power could be obtained with diffraction-limited quality from a fiber laser or amplifier. This power limit is determined by thermal and non-linear limits that combine to prevent further power scaling, irrespective of increases in mode size. However, limits to the scaling of the MFD may restrict fiber lasers to lower output powers.

Zigzag slabs for solid-state laser amplifiers: batch fabrication and parasitic oscillation suppression

We have developed a 100 W class Nd:YAG master oscillator power amplifier system based in part on an end-pumped zigzag slab power amplifier. This amplifier incorporates parasitic oscillation suppression by using roughened edges and achieves a small-signal gain coefficient (g(0)l) of 8.06. We describe a novel technique for suppression of parasitic oscillations using claddings on slab edges that significantly increases g(0)l to 11.63 and increases the single-pass extracted power in a power amplifier by 50%. Commercial use of these zigzag slab amplifiers has been limited by the time and cost of production. We describe a new batch fabrication technique that improves the quality and significantly reduces the cost of zigzag slabs.

High average power lasers for future particle accelerators

Lasers are of increasing interest to the accelerator community and include applications as diverse as stripping electrons from hydrogen atoms, sources for Compton scattering, efficient high repetition rate lasers for dielectric laser acceleration, peta-watt peak power lasers for laser wake field and high energy, short pulse lasers for proton and ion beam therapy. The laser requirements for these applications are briefly surveyed. State of the art of laser technologies with the potential to eventually meet those requirements are reviewed. These technologies include diode pumped solid state lasers (including cryogenic), fiber lasers, OPCPA based lasers and Ti:Sapphire lasers. Strengths and weakness of the various technologies are discussed along with the most important issues to address to get from the current state of the art to the performance needed for the accelerator applications. Efficiency issues are considered in detail as in most cases the system efficiency is a valuable indicator of the actual abi...

Yb:YAG master oscillator power amplifier for remote wind sensing

We have demonstrated key advances towards a solid-state laser amplifier at 1.03 microm for global remote wind sensing. We designed end-pumped zig-zag slab amplifiers to achieve high gain. We overcame parasitic oscillation limitations using claddings on the slabs total internal reflection (TIR) and edge surfaces to confine the pump and signal light by TIR and allow leakage of amplified spontaneous emission rays that do not meet the TIR condition. This enables e3, e5, and e8 single-, double-, and quadruple-pass small-signal amplifier gain, respectively. The stored energy density is 15.6 J/cm3, a record for a laser-diode end-pumped Yb:YAG zig-zag slab amplifier.

Disk motion ??? a new control element in high-brightness solid state laser design.

The brightness of cw and quasi cw solid state lasers of conventional designs is limited by stress fracture and uncorrectable phase aberration in thermally loaded stationary gain medium. By introducing physical motion of the gain medium as a new control element in the design of solid state lasers, we show the potential to significantly increase the brightness of cw and quasi cw solid state lasers. In this paper, we develop the design equations of rotary disk lasers and illustrate the design of a 1-kilowatt single mode Yb-YAG rotary disk laser.

Parametric amplification of 1.6 /spl mu/m signal in anneal- and reverse-proton exchanged waveguides

This paper reports experimental results on optical parametric amplification in anneal-proton exchanged (APE) and reverse-proton exchanged (RPE) waveguides in periodically-poled lithium niobate using 1.064 /spl mu/m pulsed YAG laser as the pump and tunable L-band external cavity diode laser as the signal.

High Peak Power, High Repetition Rate, TEM00 Q-Switched Lasers in Yb-YAG and Nd-YAG Ceramic

We report recent results in power scaling of high repetition rate TEM00 Q-switched lasers in Yb-YAG and Nd-YAG ceramic. 72.8 W of Q-switched power was obtained at 50 kHz in 69 ns pulses in Yb-YAG.

100 W, single frequency, low-noise, diffraction-limited beam from an Nd:YAG end-pumped slab MOPA for LIGO

We describe a 104 W master oscillator power amplifier system for LIGO. This design based on an endpumped Nd:YAG slab amplifier topology is single-frequency, single-polarization and diffraction limited with 89% power in the TEM00 mode.

Waveguide parametric amplification of eyesafe 1.6-μm signal for remote-sensing applications

We describe pulsed parametric amplification of CW telecom laser radiation in reverse-proton exchanged lithium niobate waveguides for generation of eyesafe narrow-linewidth muJ pulses useful for wind-sensing applications. Over 40 dB of gain was observed.

Batch Fabrication and ASE Suppression Issues in Zig-Zag Slabs for Solid-State Laser Amplifiers

We show a novel method for the batch fabrication of slabs for zig-zag solid-state laser amplifiers. We also discuss various techniques that we implemented to suppress ASE and dramatically improve the small signal gain.