A control system and apparatus for use with an ultra-fast laser is provided. In another aspect of the present invention, the apparatus includes a laser, pulse shaper, detection device and control system. A multiphoton intrapulse interference method is used to characterize the spectral phase of laser pulses and to compensate any distortions in an additional aspect of the present invention. In another aspect of the present invention, a system employs multiphoton intrapulse interference phase scan. Furthermore, another aspect of the present invention locates a pulse shaper and/or MIIPS unit between a laser oscillator and an output of a laser amplifier.

Control system and apparatus for use with ultra-fast laser

A new approach to the design of optically pumped solid-state lasers is proposed which permits lasing without detrimental heating of the laser medium. Very high average power lasers should be possible by balancing the radiated and absorbed power density at each point within the laser medium.

Lasers without internal heat generation

Recent progress in developing phased arrays of high-brightness solid-state lasers is summarized. We address the prospects for continued brightness-scaling via a model that extrapolates measured results to large numbers of array elements and provides a quantitative illustration of the features of coherent beam combination. This demonstrates that with present-day technology, both slab and fiber lasers have the capability to scale to unprecedented brightness levels.

Brightness-Scaling Potential of Actively Phase-Locked Solid-State Laser Arrays

We present a novel design for a quasi-three-level laser. The design uses a slab laser configuration with the pump light incident from the slab edge. This allows a lower threshold and better power scaling than a conventional face-pumped slab. We present an analytic description of pumping optimization, thermal distortion, and power scaling. Several point designs illustrating power scaling are also described.

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Edge-pumped quasi-three-level slab lasers: design and power scaling

The design and operation of a Nd:glass regenerative amplifier using a stimulated Brillouin scattering (SBS) phase conjugate mirror is presented. The system can be operated at 25-30 J per pulse with a pulse width of 14 ns and a pulse repetition frequency (PRF) of 6 Hz. This results in an average output power of >150 W with a peak power of 2 GW. The experimentally measured divergence of the amplifier output is 1.25/spl times/ the diffraction limit and it can be frequency doubled with >80% efficiency. The detailed considerations required for this specific amplifier design are discussed as well as how these considerations apply to the design of high average power, high beam quality laser systems in general. >

Design and operation of a 150 W near diffraction-limited laser amplifier with SBS wavefront correction

The diode array pumped kilowatt laser (DAPKL) has demonstrated more than an order of magnitude increase in brightness and average power for short pulse diode-pumped solid-state lasers since its inception in 1991. Significant advances in component technology have been demonstrated, including: development of a diffusion bonding process for producing large slabs of Nd:YAG laser material. Phase conjugation by stimulated Brillouin scattering (SBS) has been demonstrated with high reflectivity and fidelity in a simple focused geometry with input powers of 100 W. Pulse energies at 1.06 /spl mu/m of 10 J have been demonstrated with a beam quality of 1.5 times diffraction limited at the 500-W level. An average power of 875 W at 100 Hz has been obtained. Efficient frequency doubling with a record power of 165 W has been demonstrated with 5 J per pulse at 0.53 /spl mu/m. Work is ongoing to enclose the system in a compact brassboard with improved performance and long term stability.

Diode array pumped kilowatt laser

A solid-state laser architecture producing a beam of extremely high quality and brightness, including a master oscillator (10) operating in conjunction with a zig-zag amplifier (16,30), an image relaying telescope (17) and a phase conjugation cell (20). One embodiment of the laser architecture compensates for birefringence that is thermally induced in the amplifier (16), but injects linearly polarized light into the phase conjugation cell (20). Another embodiment (19) injects circularly polarized light into the phase conjugation cell (20) and includes optical components that eliminate birefringence effects arising in a first pass through the amplifier (16,30). Optional features (26) permit the use of a frequency doubler assembly to provide output at twice optical frequencies, and an electro-optical switch or Faraday rotator (71) to effect polarization angle rotation if the amplifier material (16,30) can only be operated at one polarization. The zig-zag amplifier (16,30) is cooled by flow of cooling liquid, preferably using longitudinal flow to minimize temperature gradients in a vertical direction, and has cooling channel seals (50,52) disposed in dead zones that receive no light, to minimize optical damage to the seals (50,52). Light is input to the amplifier (16) at a near normal angle of incidence, to minimize polarization by reflection and to permit a polarizer (14) to be used to extract an output beam from the amplifier (16,30). Antireflective coatings (60) on edges and on sides of the amplifier (16,30) eliminate parasitic oscillations, and wedge-shaped windows (36) provide uniform pumping by eliminating gaps between diode arrays (32).

High brightness solid-state laser with zig-zag amplifier

A high brightness diode-pumped, Nd-YAG solid state laser has been designed, fabricated, and tested. This phase conjugated master oscillator/power amplifier (MOPA) device produces 20-ns Q-switched pulses at 2500 Hz at an average power of 690 W and a beam quality of 1.1/spl times/DL when the pump diodes are operated at 27.5% duty cycle. With an external KTP doubler, this device has produced 175 W of green average power at a beam quality of 1.5 /spl times/ DL and a conversion efficiency of 45% over continuous operating times as long as one hour. This 1.06 /spl mu/m result is believed to be the highest average power brightness achieved, and the 532-nm performance is both the highest average green power and the highest average brightness ever reported.

Active tracker laser (ATLAS)

A high average power, OPO based system has been developed for the purpose of generating output in the 2 - 5 µm mid-IR band. The system uses a cw diode array - pumped, Nd:YAG master oscillator power amplifier (MOPA) as the pump source and two tandem OPOs for wavelength conversion to the mid-IR. A Type II degenerate KTP OPO was used to convert the pump beam to 2.13 µm and a Type I near degenerate zinc germanium phosphite (ZGP) OPO was used to generate broadband radiation in the 3.7 - 4.1 and 4.4 - 4.8 µm wavelength range.

High Power Conversion to Mid-IR Using KTP and ZGP OPOs

A solid-state laser architecture producing a beam of extremely high quality and brightness, including a master oscillator operating in conjunction with a zig-zag amplifier, an image relaying telescope and a phase conjugation cell. One embodiment of the laser architecture compensates for birefringence that is thermally induced in the amplifier, but injects linearly polarized light into the phase conjugation cell. Another embodiment injects circularly polarized light into the phase conjugation cell and includes optical components that eliminate birefringence effects arising in a first pass through the amplifier. Optional features permit the use of a frequency doubler assembly to provide output at twice optical frequencies, and an electro-optical switch or Faraday rotator to effect polarization angle rotation if the amplifier material can only be operated at one polarization. The zig-zag amplifier is cooled by flow of cooling liquid, preferably using longitudinal flow to minimize temperature gradients in a vertical direction, and has cooling channel seals disposed in dead zones that receive no light, to minimize optical damage to the seals. Light is input to the amplifier at a near normal angle of incidence, to minimize polarization by reflection and to permit a polarizer to be used to extract an output beam from the amplifier. Antireflective coatings on edges and on sides of the amplifier eliminate parasitic oscillations, and wedge-shaped windows provide uniform pumping by eliminating gaps between diode arrays.

Rodger C. Hilyard

Papers

Diode array pumped kilowatt laser

High brightness solid-state laser with zig-zag amplifier

Active tracker laser (ATLAS)

High Power Conversion to Mid-IR Using KTP and ZGP OPOs

Solid-state zig-zag slab optical amplifier