Maurice A. Pessot

Generation of ultrahigh peak power pulses by chirped pulse amplification

Single picosecond pulses have been amplified to the terawatt level by a table-top-size Nd:glass amplifier by using the technique of chirped pulse amplification (CPA). The divergence of the beam is twice the diffraction limit, making the brightness of this source equal to approximately 2*10/sup +18/ W/(cm-sr), which is thought to be the highest brightness yet reported. The CPA technique allows the efficient energy extraction from extremely compact amplifier systems. Amplification of chirped pulses over nine orders of magnitude, i.e. from nanojoule to the joule level, has been demonstrated. >

1000 times expansion/compression of optical pulses for chirped pulse amplification

Abstract Diffraction gratings are used in both positive and negative group velocity dispersion configurations to expand and compress an optical pulse. An expansion/compression factor of 1000 times, from 85 fs to 85 ps and back is demonstrated. This method, in conjunction with the technique of chirped pulse amplification, will make possible the production of ultrahigh peak power pulses in the terawatt to petawatt range.

Chirped-pulse amplification of 100-fsec pulses

Chirped-pulse amplification is used to generate 2-mJ pulses of 106-fsec duration in an alexandrite amplifier. Compression of the optical pulse is achieved by using a sequence of intracavity prisms in conjunction with diffraction gratings. This allows for the compensation of both linear and quadratic contributions to the dispersion from the amplifier.

Subpicosecond photoconductivity overshoot in gallium arsenide observed by electro‐optic sampling

Electro‐optic sampling of photoconductive transients on a subpicosecond time scale is used to study hot‐carrier transport in GaAs. The results reported here are interpreted as direct time‐domain observations of nonequilibrium transport on a subpicosecond time scale and they clearly show both an overshoot and bias‐dependent delay at high excitation energy which are consistent with published Monte Carlo predictions.

Chirped pulse amplification of 300 fs pulses in an alexandrite regenerative amplifier

The amplification of femtosecond dye laser pulses up to the 3.5-mJ level in an alexandrite regenerative amplifier is discussed. An expansion/compression system using diffraction gratings allows chirped amplification techniques to be used to produce peak powers upwards of 1 GW. Limitations in the chirped pulse amplification of ultrashort pulses due to intracavity dispersive elements are discussed. >

Theoretical and experimental investigations of subpicosecond photoconductivity

Monte Carlo methods are used to study photoconductive transients in gallium arsenide. It is demonstrated that working with presently established ranges for the Γ‐L coupling coefficient, the existence of a velocity overshoot at moderate fields cannot be exactly predicted. The role of negative velocity electrons in the initial transient for short wavelength excitation is also demonstrated. Details of an actual experiment are described and evaluated against a model which incorporates the Monte Carlo simulation into a transmission line structure with a frequency‐dependent characteristic impedance. The results demonstrate that an appropriately designed experiment can observe subpicosecond carrier transport transients.

Short pulse amplification in tunable solid state materials

We describe our work on the amplification of short pulses in tunable solid state materials; specifically alexandrite and Ti:sapphire. Our goal is to amplify femtosecond range pulses to the joule level in a table top size laser. We will describe our results which show that such a laser is now feasible.

Pr:YLF, intracavity-pumped, room-temperature upconversion laser.

Cw room-temperature upconversion laser operation is reported in Pr:YLF at 640 and 607 nm. An intracavitypumping scheme that uses a Yb:YAG laser operating at 1030 nm to pump the weak (3)H(4) ? (1)G(4) ground-state transition of Pr:YLF is used to populate the intermediate metastable level. An excited-state absorption at 867 nm is then used to populate the (3)P(0) and (3)P(1) upper states. An average output power of 3.5 mW was obtained at 607 nm, with a combined input pump power of 2.5 W.

Regenerative amplification in alexandrite of pulses from specialized oscillators

An alexandrite regenerative amplifier, used to amplify the output of various specialized oscillators, is described. Nanosecond pulses from a narrow-frequency CW-pumped dye laser, picosecond pulses from a gain-switched diode laser, and femtosecond pulses from a synchronously pumped dye laser were amplified by 6-10 orders of magnitude in a single stage while conserving the temporal and spectral profiles characteristic to the oscillators. >

A 1.55-/spl mu/m solid-state laser source for DWDM applications

We describe the design and operation of a 1550-nm diode pumped Er,Yb:glass laser with >130 mW of output power and a free running linewidth of /spl sim/22 kHz. Due to the low frequency relaxation oscillation, near shot limited relative intensity noise performance is obtained throughout the radio frequency (RF) range of interest for cable television and dense wavelength division multiplexed (CATV/DWDM) applications. For long-haul spans an intracavity lithium niobate phase modulator allows for chirping of the linewidth to bandwidths and at rates sufficient to defeat stimulated Brillouin scattering (SBS). For certain applications, the high output power can eliminate the need for an erbium-doped fiber amplifier (EDFA).