Modelocked fiber laser resonators may be coupled with optical amplifiers. An isolator optionally may separate the resonator from the amplifier. A reflective optical element on one end of the resonator having a relatively low reflectivity may be employed to couple light from the resonator to the amplifier. Enhanced pulse-width control may be provided with concatenated sections of both polarization-maintaining and non-polarization-maintaining fibers. Apodized fiber Bragg gratings and integrated fiber polarizers may also be included in the laser cavity to assist in linearly polarizing the output of the cavity. Very short pulses with a large optical bandwidth may be obtained by matching the dispersion value of the grating to the inverse of the dispersion of the intra-cavity fiber. Frequency comb sources may be constructed from such modelocked fiber oscillators. Low dispersion and an in-line interferometer that provides feedback may assist in controlling the frequency components output from the comb source.

The invention relates to a microchip laser having a monolithic resonator (1) which has a birefringent laser crystal (2), wherein a laser beam (9) decoupled from the resonator, (1) which has a laser wavelength, exits the resonator (1) along a laser beam axis (12) and the length (L) of the resonator (1) is less than 150 m based on a direction of the laser beam axis (12). The laser crystal (2) has a thickness (D) based on the direction of the laser beam axis (12) such that, in the case of a light beam (16) having the laser wavelength occurring in the direction of the laser beam axis (12) being incident on the laser crystal (2) between the ordinary and extraordinary beam (17, 19), in which the light beam (16) is divided in the laser crystal (2), a phase shift in the range of /2 +//4 occurs in a single pass through the laser crystal (2).

A surface-emitting semiconductor laser system contains at least one MQW unit of at least three constituent QWs, axially separated from one another substantially non-equidistantly. The MQW unit is located within the axial extent covered, in operation of the laser, by a half-cycle of the standing wave of the field at a wavelength within the gain spectrum of the gain medium; immediately neighboring nodes of the standing wave are on opposite sides of the MQW unit. So-configured MQW unit can be repeated multiple times and/or complemented with individual QWs disposed outside of the half-cycle of the standing wave with which such MQW unit is associated. The semiconductor laser further includes a pump source configured to input energy in the semiconductor gain medium and a mode-locking element to initiate mode-locking.

A fiber laser oscillator comprises an active fiber for providing a lasing light having a selected wavelength band, a saturable absorber assembly coupled to a first end of the active fiber, a pump source for providing a pump light having wavelengths except the selected wavelength band, an optical component coupled to the second end of the active fiber and the pump source. The optical component comprises a thin film filter for transmitting the lasing light for a first time and reflecting the pump light and a reflector for reflecting the lasing light transmitted for the first time through the thin film filter. The lasing light reflected by the reflector transmits through the thin film filter for a second time and overlaps with the pump light reflected by the thin film filter.

An illumination system is disclosed for providing dual excitation wavelength illumination for non-linear optical microscopy and micro-spectroscopy. The illumination system includes a laser system for providing a first train of pulses at a center optical frequency .sub.1, a frequency converting system for providing at least a second train of pulses at a center optical frequency .sub.2 and a third train of pulses at a center optical frequency .sub.3, where .sub.2 is different from .sub.1 and .sub.3 responsive to the first train of pulses, an amplifier system for amplifying the second train of pulses to provide an amplified second train of pulses, and an adjustment means for adjusting a time delay between the amplified second train of pulses and the third train of pulses for the dual-excitation wavelength illumination.

Apparatus and methods for producing ultrashort optical pulses are described. A high-power, solid-state, passively mode-locked laser can be manufactured in a compact module that can be incorporated into a portable instrument for biological or chemical analyses. The pulsed laser may produce sub-100-ps optical pulses at a repetition rate commensurate with electronic data-acquisition rates. The optical pulses may excite samples in reaction chambers of the instrument, and be used to generate a reference clock for operating signal-acquisition and signal-processing electronics of the instrument.

A fiber laser having an optical cavity that has an optical fiber and a curved mirror for imaging light leaving the fiber back into the fiber. The optical fiber has a round trip dispersion loss of less than 200000 fs.sup.2. The round trip length of the optical fiber is less than 2.3 m.

A laser utilizes a cavity design which allows the stable generation of high peak power pulses from mode-locked multi-mode fiber lasers, greatly extending the peak power limits of conventional mode-locked single-mode fiber lasers. Mode-locking may be induced by insertion of a saturable absorber into the cavity and by inserting one or more mode-filters to ensure the oscillation of the fundamental mode in the multi-mode fiber. The probability of damage of the absorber may be minimized by the insertion of an additional semiconductor optical power limiter into the cavity.

The invention describes classes of robust fiber laser systems usable as pulse sources for Nd: or Yb: based regenerative amplifiers intended for industrial settings. The invention modifies adapts and incorporates several recent advances in FCPA systems to use as the input source for this new class of regenerative amplifier.

Modelocked fiber laser resonators may be coupled with optical amplifiers. An isolator optionally may separate the resonator from the amplifier. A reflective optical element on one end of the resonator having a relatively low reflectivity may be employed to couple light from the resonator to the amplifier. Enhanced pulse-width control may be provided with concatenated sections of both polarization-maintaining and non-polarization-maintaining fibers. Apodized fiber Bragg gratings and integrated fiber polarizers may also be included in the laser cavity to assist in linearly polarizing the output of the cavity. Very short pulses with a large optical bandwidth may be obtained by matching the dispersion value of the grating to the inverse of the dispersion of the intra-cavity fiber. Frequency comb sources may be constructed from such modelocked fiber oscillators. Low dispersion and an in-line interferometer that provides feedback may assist in controlling the frequency components output from the comb source.