The invention relates to scanning pulsed laser systems for optical imaging. Coherent dual scanning laser systems (CDSL) are disclosed and some applications thereof. Various alternatives for implementation are illustrated, including highly integrated configurations. In at least one embodiment a coherent dual scanning laser system (CDSL) includes two passively modelocked fiber oscillators. The oscillators are configured to operate at slightly different repetition rates, such that a difference f.sub.r in repetition rates is small compared to the values f.sub.r1 and f.sub.r2 of the repetition rates of the oscillators. The CDSL system also includes a non-linear frequency conversion section optically connected to each oscillator. The section includes a non-linear optical element generating a frequency converted spectral output having a spectral bandwidth and a frequency comb comprising harmonics of the oscillator repetition rates. A CDSL may be arranged in an imaging system for one or more of optical imaging, microscopy, micro-spectroscopy and/or THz imaging.

The present invention relates to an external cavity tunable laser and a cavity mode locking method thereof. In an embodiment, an external cavity tunable laser comprises a semiconductor amplifier having a partial reflective film provided on one end and an anti-reflective film provided on the other end, a cavity mirror provided at the anti-reflective end to define an external cavity therebetween, a large-range phasing assembly and a quick phasing assembly provided to adjust the optical length of the external cavity independently, an optical power detector provided to detect the optical power of the light output from the semiconductor amplifier, and a control unit in communication with the optical power detector, the large-range phasing assembly, and the quick phasing assembly.

The present disclosure relates to the design of fiber frequency comb lasers with low carrier phase noise. Examples of these low carrier phase noise oscillators can be constructed from both soliton and dispersion compensated fiber lasers via the use of intra-cavity amplitude modulators such as graphene modulators. In low carrier phase noise dispersion compensated fiber frequency comb lasers, graphene and/or bulk modulators can further be used, for example, for phase locking of one comb line to an external continuous wave (cw) reference laser via high bandwidth control of the repetition rate of the comb laser via the graphene modulator. As a result a low phase noise radio frequency (RF) signal can be generated. In some implementations, a frequency comb exhibiting phase noise suppression of at least about 10 dB over a frequency range up to about 100 kHz is provided.

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.

A method for operating a laser device, including providing a laser pulse in a resonator so that the laser pulse circulates in the resonator, the laser pulse having a carrier wave; determining an offset frequency (f.sub.0) of the frequency comb corresponding to the laser pulse, the frequency comb having a plurality of laser modes (f.sub.m) at a distance (f.sub.rep) from one another, the frequencies of which can be described by the formula: f.sub.m=m*f.sub.rep+f.sub.0, m being a natural number, and varying the offset frequency (f.sub.0) by varying a geometric phase () that is imparted to the carrier wave of the laser pulse per resonator circulation.

There was the problem that the pressure of the laser medium rises from the target value by the heat when generating laser light. The laser oscillator includes a controller, laser medium flow path, resonator part, blower, pressure detecting part, laser medium supply-exhaust part, and temporary stop command part. The controller controls the resonator part to stop to generate laser light if a temporary stop is commanded, controls the blower 18 to slow the rotational speed of the blower from the first rotational speed to the second rotational speed, and controls the laser medium supply-exhaust part so that the pressure is the second target value lower than the pressure at the time when the rotational speed of the blower is the second rotational speed.

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.

A fiber laser, null coupler acoustic Q-switch, fiber amplifier and feedback system is described for generation of high power laser pulses.

One or more embodiments relates to a system for simultaneously detecting vibration and the presence of a target gas having a tunable fiber ring laser in electronic and optical communication with a vibration sensor and a gas detection sensor. One or more embodiments relate to a method for simultaneously measuring vibration and detecting the presence of a target gas in an environment having the steps of providing a system for simultaneously measuring vibration and detecting a target gas into an environment; sending an optical signal to a vibration sensor and gas detection sensor; and collecting and analyzing modified signals from the vibration sensor and gas detection sensor.

A radiation field generating system comprising an optical unit with an optical assembly which defines an optical path is provided, wherein the optical unit is operable in several different operation conditions and the optical assembly comprises at least one optical switching component with which switching between at least two different operation conditions of the several operation conditions can be performed.