A passively mode-locking laser and corresponding method is described. The laser comprises a resonator (2) terminated by first (3) and second (4) mirrors and folded by a third (5) and fourth (6) mirror. The third mirror comprises a reflector (14) surmounted by a multilayer semiconductor gain medium (15) including at least one quantum well layer while the second mirror (4) comprises an intensity saturable mirror. The resonator is configured to provide a cross sectional area of an intra cavity resonating field on the intensity saturable mirror that is greater than or equal to a cross sectional area of the intra cavity resonating field on the multilayer semiconductor gain medium. This arrangement provides a passively mode-locking laser that exhibits increased stability when compared to those systems known in the art.

A method of operating a q-switch RE,XAB laser includes: providing a pump bias current to a pump source, the pump source directed to an RE:XAB gain medium, the RE:XAB gain medium within a resonator cavity, where X is selected from Ca, Lu, Yb, Nd, Sm, Eu, Gd, Ga, Tb, Dy, Ho, Er, and where RE is selected from Lu, Y, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Pr, Tm, Cr, Ho, with a bias current level below a lasing threshold of the RE:XAB gain medium; providing a pump pulse to the gain medium, the pump pulse of the lasing threshold of the RE:XAB gain medium, the pump pulse causing the RE:XAB gain medium to emit a laser pulse; and reducing the pump bias current to at least below the gain medium lasing threshold, the combination of the pump bias, the pump pulse, and the pump reduction having a current profile.

Low phase noise radio frequency (RF) sources generated by voltage controlled oscillators (VCOs) are described. Optical modulators driven by a VCO may be used to generate optical side-bands to cw lasers. The spectral extent of said side-bands can be increased via frequency broadening in highly nonlinear waveguides. Free running mode locked low phase noise comb oscillators can be used as reference oscillators to generate beat signals between those side-bands and individual comb modes at distal spectral regions, thereby creating an error signal used to reduce the phase noise of VCOs and the generation of low phase noise RF signals. VCO phase noise may be reduced by using free-running modelocked comb lasers phase locked to external frequency references, by omitting a reference comb and using a nonlinear interferometer for generating an error signal, or by locking a slave comb to the modulation frequency of an intra-cavity modulator driven by the VCO.

A fiber laser device includes: a housing; a first optical element configured to include a first fiber and a first fiber connector; a second optical element configured to include a second fiber and a second fiber connector; and a movable holder configured to hold the second fiber connector and be movable so that an orientation of the second fiber connector changes between a first orientation and a second orientation. The first optical element and the second optical element are optically connectable via the first fiber connector and the second fiber connector, a first opening is formed in a wall portion of the housing, the first orientation is an orientation when the first optical element and the second optical element are optically connected, and the second orientation is an orientation in which an end surface of the second fiber is exposed through the first opening.

A fiber laser device includes: a housing; a first optical element configured to include a first fiber and a first fiber connector; a second optical element configured to include a second fiber and a second fiber connector; and a movable holder configured to hold the second fiber connector and be movable so that an orientation of the second fiber connector changes between a first orientation and a second orientation. The first optical element and the second optical element are optically connectable via the first fiber connector and the second fiber connector, a first opening is formed in a wall portion of the housing, the first orientation is an orientation when the first optical element and the second optical element are optically connected, and the second orientation is an orientation in which an end surface of the second fiber is exposed through the first opening.

Systems and methods are described for producing an amplitude-modulated laser pulse train. The laser pulse train can be used to cause fluorescence in materials at which the pulse trains are directed. The parameters of the laser pulse train are selected to increase fluorescence relative to a constant-amplitude laser pulse train. The amplitude-modulated laser pulse trains produced using the teachings of this invention can be used to enable detection of specific molecules in applications such as gene or protein sequencing.

Systems and methods are described for producing an amplitude-modulated laser pulse train. The laser pulse train can be used to cause fluorescence in materials at which the pulse trains are directed. The parameters of the laser pulse train are selected to increase fluorescence relative to a constant-amplitude laser pulse train. The amplitude-modulated laser pulse trains produced using the teachings of this invention can be used to enable detection of specific molecules in applications such as gene or protein sequencing.

A laser device for laser detection and ranging (LiDAR), comprising: a laser oscillator configured for emitting a pulsed laser beam, a laser beam amplifier disposed on the laser beam path, a pumping unit disposed between the laser oscillator and the laser beam amplifier and configured to, when receiving an incoming continuous pumping beam having the pumping wavelength, transmit the laser beam along the laser direction; send the pumping beam for pumping the laser oscillator in the opposite direction to the laser direction, and transmit a reflected part of the pumping beam for pumping the laser beam amplifier, in the laser direction.

A laser device for laser detection and ranging (LiDAR), comprising: a laser oscillator configured for emitting a pulsed laser beam, a laser beam amplifier disposed on the laser beam path, a pumping unit disposed between the laser oscillator and the laser beam amplifier and configured to, when receiving an incoming continuous pumping beam having the pumping wavelength, transmit the laser beam along the laser direction; send the pumping beam for pumping the laser oscillator in the opposite direction to the laser direction, and transmit a reflected part of the pumping beam for pumping the laser beam amplifier, in the laser direction.

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.