A. J. Schmidt

Mode locking with cross-phase and self-phase modulation.

Cross-phase and self-phase modulation are used for self-sustained mode locking of a high-power neodymium glass fiber laser. Stable pulses with a FWHM as short as 70 fs and pulse energies of as much as 1 nJ are generated at a wavelength of 1.064 microm.

Femtosecond solid-state lasers

The emergence of new ultrafast optical modulation techniques has opened the way towards a new femtosecond laser technology based on solid-state gain media. The authors address the requirements for stable ultrashort pulse generation in these novel femtosecond sources. The theoretical considerations are backed up by experimental results obtained with a number of different laser systems. The conclusions drawn from the presented theoretical and experimental investigations provide general guidelines for the design and optimization of a wide range of femtosecond solid-state laser oscillators. >

Operation of a femtosecond Ti:sapphire solitary laser in the vicinity of zero group-delay dispersion

We report the operating characteristics of a self-mode-locked Ti:sapphire solitary laser at reduced group-delay dispersion. The generation of asymptotically equal to 12.3 fs near-sech(2) optical pulses at 775 nm is reported, together with experimental evidence for the dominant role of third-order dispersion (TOD) as a limiting factor to further pulse shortening in the oscillator. At reduced second-order dispersion excessive residual TOD is shown to lead to dispersive wave generation, and the position of the dispersive resonance is used to determine the ratio of the net second- and third-order intracavity dispersions. Since the magnitude of TOD rapidly decreases with increasing wavelength in prism-pair dispersion-compensated resonators, the oscillator presented has the potential for producing sub-10-fs pulses in the 800-nm wavelength region.

Additive-pulse-compression mode locking of a neodymium fiber laser.

The generation of bandwidth-limited shoulder-free 125-fsec pulses by additive-pulse-compression mode locking of a neodymium glass laser is described. An all-fiber nonlinear amplifying loop mirror is employed as a fast saturable absorber and permits stable pulse generation under the condition of large pulse shaping in the cavity.

Generation of 33-fs optical pulses from a solid-state laser.

Using the results of recent theoretical research, we present practical guidelines for the optimization of femtosecond solid-state oscillators and demonstrate reproducible sub-40-fs pulse generation in a synchronously pumped Ti:sapphire laser.

Sub-20-fs, kilohertz-repetition-rate Ti:sapphire amplifier

A simple four-pass Ti:sapphire amplifier is seeded by sub-10-fs pulses generated from a mirror-dispersion-controlled Ti:sapphire laser. Pulses of 17-18-fs duration with energies up to 50 and 100 microJ have been produced at repetition rates of 2 and 1 kHz, respectively. Because of the absence of a pulse stretcher, this performance is achieved from an extremely compact system.

Femtosecond pulse generation from a synchronously pumped Ti:sapphire laser.

We report femtosecond mode locking of a Ti:sapphire laser synchronously pumped by a mode-locked, frequency-doubled Nd:YLF laser. Stable tunable 70-fs pulses are generated in a TEM(00) output without the need for stabilization of the cavity length.

Self-starting additive-pulse mode locking of a Nd:glass laser.

Self-starting cw mode-locked operation of a Nd:glass laser has been achieved by using a nonlinear external resonator. The coupled cavity incorporating an optical fiber initiates and sustains ultrashort-pulse generation, resulting in a stable train of 380-fsec pulses.

Femtosecond passive mode locking of a solid‐state laser by a dispersively balanced nonlinear interferometer

A Michelson interferometer containing a nonlinear fiber in one arm and dispersion control in the other arm has been used for passive mode locking of a continuous wave Nd:glass laser. We discuss scaling issues and demonstrate the usefulness of this technique by generating ≊300 fs pulses with only Pf≊15 mW of average power in the fiber and ≊100 fs pulses with a self‐starting threshold of Pf≊100 mW.

Hard-aperture Kerr-lens mode locking

Self-focusing by a Kerr nonlinearity in combination with an intracavity aperture creates a power-dependent loss in lasers, which has been used as a method for passive mode locking of lasers. An analytical treatment is presented that yields closed-form expressions for the modulation efficiency. Comparisons between analytical results and numerical calculations are performed. General features of this mode-locking technique are discussed, and a procedure for the optimization of hard-aperture Kerr-lens mode-locking performance is given.