The laser device includes a first mirror and a second mirror forming a resonator, a gain medium disposed between the first mirror and the second mirror and having a light emitting surface, an antireflection film provided on the light emitting surface of the gain medium, at least one optical element disposed between the gain medium and the second mirror, and a diffraction grating disposed between the optical element and the second mirror. The gain medium is a semiconductor layered body including an active layer and having a varying gain distribution in at least a first direction within the light emitting surface, and includes no waveguide.

The semiconductor laser device includes: semiconductor laser elements; lenses; a deflection element; a wavelength dispersion element that wavelength-couples emitted light beams to form coupled light; and a partial reflection mirror. The lenses include a first lens that reduces a divergence angle of the emitted light beams in a first axis direction, and a second lens that is disposed between the first lens and the wavelength dispersion element and reduces the divergence angle of the laser beams in a second axis direction. The deflection element has planes each corresponding to the emitted light beams, at least one plane among the planes is inclined with respect to an optical axis of a corresponding one of the emitted light beams, which corresponds to each of the at least one plane, and the emitted light beams overlap one another on the wavelength dispersion element.

A spectral beam combining system includes a plurality of input fibers and a prism having a curved input surface. The plurality of input fibers are attached to the curved input surface. The spectral beam combining system also includes an immersion grating defined on a second surface of the prism, a protective cap disposed over the immersion grating, and an output surface.

An external optical feedback element (108) for tuning an output beam of a gas laser (102) having multiple wavelengths includes a partially reflective optical element (108) positioned on a beam path of the output beam (106) outside of an internal optical cavity of the gas laser (102), and a stage (114) to support the optical element and adjust rotation, horizontal tilt angle, and vertical tilt angle of the optical element with respect to the beam path. The output beam (106) is partially reflected at the optical element (108) and fed back into the internal optical cavity of the gas laser (102), with the intensity varying for multiple wavelengths and adjusted by changing rotation, horizontal tilt angle and vertical tilt angle of the optical element. Thereby, a variable feedback of the output beam into the internal optical cavity of the gas laser is provided, which leads to a selective output wavelength of the gas laser, either at a single line or at multiple lines simultaneously. This setup may allow to control the wavelength of a commercial CO2 gas laser without a modification of the laser itself by adding a coupled cavity with a wavelength selective element like a grating to the given gas laser resonator.

Systems and methods for ring laser gyroscopes (RLGs) are provided. An RLG includes a traveling-wave resonator cavity with three or more mirrors and a gain medium positioned in the traveling-wave resonator cavity between two of the three or more mirrors. The gain medium is a solid-state gain medium or a nonlinear optical medium. The RLG further includes a first pump laser and a second pump laser to pump the gain medium in different directions and generate first and second lasing signals that traverse the traveling-wave resonator cavity in a opposite directions. The RLG further includes first and second photodetectors to measure levels of the first and second lasing signals. The RLG further includes at least one processor configured to adjust a power level of the first pump laser and/or a power level of the second pump laser based on the measured power levels of the first and second lasing signals.

Disclosed in the present invention is a semiconductor laser, which includes one or more semiconductor chips (1-1), a total length of a gain region (1-11A) of a light-emitting unit (1-11) of each of the semiconductor chips (1-1) in a slow axis direction being 1 mm˜10 cm; a laser resonant cavity configured to adjust semiconductor laser emitted by the light-emitting unit (1-11) to resonate in the slow axis direction, so that the size of the gain region (1-11A) of the light-emitting unit (1-11) in the slow axis direction matches a fundamental mode spot radius ω.sub.0; and a fast-axis collimating element (FAC) disposed in the laser resonant cavity and configured to collimate the laser emitted by the light-emitting unit (1-11) in a fast axis direction. The semiconductor laser according to an embodiment of the present invention can improve the high-power output capability of the gain region on the one hand, and improve the beam quality on the other hand, which can achieve a high beam quality output of M.sup.2<2.

According to various embodiments, a system for stabilizing operation of semiconductor laser frequency combs via optical feedback is disclosed. The system includes an external cavity having a beam-splitter, polarizer, and mirror or partially reflective element mounted on a translational stage. The external cavity and a laser facet of the semiconductor laser form an external optical resonator for coupling light to a laser cavity.

This invention proposes to use a specially designed layered nonlinear optic (LNO) for intracavity harmonic generation. The LNO generates the harmonic and guides the generated harmonic beam to a different path from the fundamental beam path with total internal reflection, a phenomenon that all lights are reflected when lights in one (“internal”) optic strike sufficiently obliquely against the interface with a second (“external”) optic, in which the refractive index is lower than that in the internal optic. No coating is necessary for the harmonic inside the fundamental beam laser cavity. The generated harmonic beam does not travel through any surface inside the fundamental beam cavity, either. Hence this invention improves the reliability of intracavity harmonic generation laser especially if the harmonic is in the UV range.

Apparatus, systems and methods to spectrally beam combine a group of diode lasers in an external cavity arrangement. A dichroic beam combiner or volume Bragg grating beam combiner is placed in an external cavity to force each of the diode lasers or groups of diode lasers to oscillate at a wavelength determined by the passband of the beam combiner. In embodiments the combination of a large number of laser diodes in a sufficiently narrow bandwidth to produce a high brightness laser source that has many applications including as to pump a Raman laser or Raman amplifier.

Systems and methods for ring laser gyroscopes (RLGs) are provided. An RLG includes a traveling-wave resonator cavity with three or more mirrors and a gain medium positioned in the traveling-wave resonator cavity between two of the three or more mirrors. The gain medium is a solid-state gain medium or a nonlinear optical medium. The RLG further includes a first pump laser and a second pump laser to pump the gain medium in different directions and generate first and second lasing signals that traverse the traveling-wave resonator cavity in a opposite directions. The RLG further includes first and second photodetectors to measure levels of the first and second lasing signals. The RLG further includes at least one processor configured to adjust a power level of the first pump laser and/or a power level of the second pump laser based on the measured power levels of the first and second lasing signals.