Systems and methods for an injection locking RFOG are described herein. In certain embodiments, a system includes an optical resonator. The system also includes a laser source configured to launch a first laser for propagating within the optical resonator in a first direction and a second laser for propagating within the optical resonator in a second direction that is opposite to the first direction, wherein the first laser is emitted at a first launch frequency and the second laser is emitted at a second launch frequency. Moreover, the system includes at least one return path that injects a first optical feedback for the first laser and a second optical feedback for the second laser, from the optical resonator, into the laser source, wherein the first and second optical feedbacks respectively lock the first and second launch frequencies to first and second resonance frequencies of the optical resonator.

An optical oscillator according to an embodiment includes a first reflecting portion that transmits light having a first wavelength and reflects light having a second wavelength different from the first wavelength, a second reflecting portion that forms an unstable resonator together with the first reflecting portion and reflect light having the second wavelength, a laser medium that is disposed between the first reflecting portion and the second reflecting portion and emits light having the second wavelength due to incidence of light having the first wavelength, and a saturable absorption portion disposed on a side opposite to the first reflecting portion when viewed from the laser medium in the one direction, the first reflecting portion includes an incidence surface on which light having the first wavelength is incident, on a side opposite to the laser medium, a size of the second reflecting portion is smaller than a size of the first reflecting portion when viewed in the one direction, at least a part of a surface of the saturable absorption body on the side opposite to the laser medium includes a curved region curved toward the laser medium side, and the second reflecting portion is a dielectric multilayer film provided in the curved region.

An extra cavity harmonic generator system may produce a round, non-astigmatic third harmonic output beam from a nominally round, non-astigmatic, diffraction limited input fundamental beam. The system may include a second harmonic generation crystal. An input fundamental beam size is expanded in a non-walkoff direction for the SHG crystal at the SHG crystal input face. A higher harmonic generation crystal has an output face oriented at an oblique angle of incidence in a non-walkoff direction for the HHG crystal such that an output higher harmonic beam size is contracted in this direction. Expansion of the input fundamental beam at the SHG crystal input face exceeds reduction of third harmonic beam at the HHG crystal output face.

A narrow linewidth laser in which an all-optical feedback line-up is used to improve the linewidth from a conventional laser source, such as a laser diode. The feedback line-up comprises an optical device having a controllable unbalanced optical coupler arranged on a cavity input path to couple a source signal from the laser source into the optical cavity, and to couple a seed signal received back from the optical cavity into the laser source. The seed signal has a lower power than the source signal. The unbalanced optical coupler may be an optical isolator arranged to couple the seed signal into the laser source at a power level selected to promote preferential stimulated emission within a narrower linewidth. By controlling the power of seed signal such that only a small portion thereof influences the lasing cavity, the narrowing effect of the preferential stimulated emission can be enhanced.

A titanium-sapphire laser apparatus may include a continuous wave oscillation laser unit, an amplification oscillator, a pulsed laser unit, an error detector, an error controller, and an optical path length corrector. The amplification oscillator may include an optical resonator and a titanium-sapphire crystal that is provided in an optical path in the optical resonator. The error detector may be provided in an optical path of leak light of seed light from the optical resonator, and may detect an optical path length error between an optical path length in the optical resonator and a positive integer multiple of a wavelength of the seed light and output an optical path length error signal. The optical path length corrector may vary the optical path length in the optical resonator on a basis of a signal resulting from adding a correction value to the optical path error signal.

A non-reciprocal optical assembly for injection locking a laser to a resonator is described. The laser emits a light beam, and the resonator receives the light beam and returns a feedback light beam to the laser such that the feedback light beam causes injection locking. The non-reciprocal optical assembly is interposed between and optically coupled to the laser and the resonator. The non-reciprocal optical assembly includes a first port that receives the light beam from the laser, and a second port that outputs the light beam to the resonator and receives the feedback light beam from the resonator. The first port also outputs the feedback light beam to the laser. The light beam passes through the non-reciprocal optical assembly with a first power loss, and the feedback light beam passes through the non-reciprocal optical assembly with a second power loss (the first power loss differs from the second power loss).

A vertical external-cavity surface-emitting laser includes: a resonator comprising at least two mirrors; a semiconductor laser medium disposed in the resonator; and a Q switch provided in the resonator.

Aspects of the present disclosure are directed to methods and apparatuses for generating laser light. As may be implemented in accordance with one or more embodiments, laser light is generated at a laser light source and is modulated in response to a frequency modulation signal, to generate a plurality of different wavelengths of laser light. The frequency modulation signal is generated, for each particular one of the wavelengths of laser light, at a respective seeding frequency corresponding to the particular one of the wavelengths in which the seeding frequency is different for each of the different wavelengths. Such an approach may, for example, involve generating the frequency modulation signal with a frequency generator circuit and using the frequency modulation signal to control an electro-optical modulator for modulating the wavelength of the laser light.

The present invention provides a burst-laser generator using an optical resonator which produces high pulse-strength of burst-laser in order to conduct laser Compton scattering, comprising: a self-oscillation amplifying optical loop-path and an external optical resonator to burst-amplify laser, wherein, laser supplied by an exciting laser source is self-oscillation amplified with the self-oscillation amplifying optical loop-path and further burst-amplified with the external optical resonator.

A system for optical comb carrier envelope offset frequency control includes a mode-locked oscillator. The mode-locked oscillator produces an output beam using an input beam and one or more control signals. The output beam includes a controlled carrier envelope offset frequency. A beat note generator produces a beat note signal using a portion of the output beam. A control signal generator produces the one or more control signals to set the beat note signal by modulating the intensity of the input beam within the mode locked oscillator. Modulating the intensity comprises using a Mach-Zehnder intensity modulator or using an intensity modulated external laser to affect a gain medium within the mode-locked laser.