Chirped-Pulse Oscillators: Generating Microjoule Femtosecond Pulses at Megahertz Repetition Rate

The maximum energy achievable directly from conventional Ti:sapphire oscillators has been limited by the onset of instabilities such as cw-generation and pulse splitting because of the high intensity in the laser medium. Generation of microjoule pulses at megahertz repetition rates are of special interest in many areas of science and technology. The main subject of this thesis is the development of high energy Ti:sapphire oscillators at megahertz repetition rate. The main concept that was applied to overcome the difficulties pointed out above was to operate the laser in the positive dispersion regime. By operating the laser in this regime, intracavity picosecond pulses are generated that can be externally compressed down to femtosecond pulse durations. The long pulse duration inside the laser offers an elegant way to reduce pulse instabilities by decreasing the intracavity intensity via pulse stretching. Drawing on this concept, Ti:sapphire chirped-pulse oscillators delivering sub-50-fs pulses of 0.5 uJ and 60 nJ energy are demonstrated at average power levels of 1 and 4 W (repetition rate: 2 MHz and 70 MHz), respectively. The 0.5 uJ pulses have a peak power in excess of 10 MW. By locking a 76-MHz chirped-pulse oscillator to a femtosecond-enhancement cavity 7.8 uJ pulses with 55 fs pulse duration were achieved. High harmonic generation was demonstrated in a Xenon target placed close to the enhancement cavity focus.

[1]  See Leang Chin,et al.  Ultrafast white-light continuum generation and self-focusing in transparent condensed media , 1999 .

[2]  Jun Ye,et al.  References and Notes Supporting Online Material Broadband Cavity Ringdown Spectroscopy for Sensitive and Rapid Molecular Detection , 2022 .

[3]  Charles K. Rhodes,et al.  Studies of multiphoton production of vacuum-ultraviolet radiation in the rare gases , 1987 .

[4]  G. Tempea,et al.  Self-phase-matched high harmonic generation , 2000, Physical review letters.

[5]  M. Teague.  Deterministic phase retrieval: a Green’s function solution , 1983 .

[6]  S. Sebban,et al.  Experimental observation of anomalous high harmonics at low intensities , 2004 .

[7]  Jinhai Si,et al.  Periodic nanovoid structures via femtosecond laser irradiation. , 2005, Nano letters.

[8]  A. Baltuska,et al.  Generation and Measurement of Intense Phase-Controlled Few-Cycle Laser Pulses , 2005 .

[9]  L. Keldysh,et al.  IONIZATION IN THE FIELD OF A STRONG ELECTROMAGNETIC WAVE , 1964 .

[10]  Sergei I Yakovlenko.  On reasons for strong absorption of light in an optical fibre at high temperature , 2004 .

[11]  M. Houssin,et al.  Ring cavity enhanced second harmonic generation of a diode laser using LBO crystal , 1998 .

[12]  M. Teague.  Irradiance moments: their propagation and use for unique retrieval of phase , 1982 .

[13]  John L. Hall,et al.  Laser phase and frequency stabilization using an optical resonator , 1983 .

[14]  Gaeta.  Catastrophic collapse of ultrashort pulses , 2000, Physical review letters.

[15]  Fumiyo Yoshino,et al.  Heat accumulation effects in femtosecond laser-written waveguides with variable repetition rate. , 2005, Optics express.

[16]  M. Obara,et al.  Self-fabrication of void array in fused silica by femtosecond laser processing , 2005 .

[17]  T. Brabec,et al.  Phase sensitivity of high-order harmonic generation with few-cycle laser pulses , 1999 .

[18]  P. Corkum,et al.  Plasma perspective on strong field multiphoton ionization. , 1993, Physical review letters.

[19]  Jun Ye,et al.  Output coupling methods for cavity-based high-harmonic generation. , 2006, Optics express.

[20]  Ferenc Krausz,et al.  Synthesis and manufacturing the mirrors for ultrafast optics , 2005, SPIE Optical Systems Design.

[21]  Nicholas F. Borrelli,et al.  Study of femtosecond-laser-written waveguides in glasses , 2002 .

[22]  E. Mazur,et al.  Optical loss measurements in femtosecond laser written waveguides in glass , 2006 .

[23]  L'Huillier,et al.  High-order harmonic generation in rare gases with a 1-ps 1053-nm laser. , 1993, Physical review letters.

[24]  Ivanov,et al.  Theory of high-harmonic generation by low-frequency laser fields. , 1994, Physical review. A, Atomic, molecular, and optical physics.

[25]  A. Bartels.  Gigahertz Femtosecond Lasers , 2005 .

[26]  L. A. Lompré,et al.  Multiple-harmonic conversion of 1064 nm radiation in rare gases , 1988 .

[27]  Peter R Herman,et al.  Low-loss Type II waveguide writing in fused silica with single picosecond laser pulses. , 2006, Optics express.

[28]  J. Diels,et al.  Stabilization of femtosecond lasers for optical frequency metrology and direct optical to radio frequency synthesis. , 2001, Physical review letters.

[29]  Jun Ye,et al.  Nonlinear dynamics inside femtosecond enhancement cavities. , 2005, Optics express.