The present disclosure provides a method for aligning a master oscillator power amplifier (MOPA) system. The method includes ramping up a pumping power input into a laser amplifier chain of the MOPA system until the pumping power input reaches an operational pumping power input level; adjusting a seed laser power output of a seed laser of the MOPA system until the seed laser power output is at a first level below an operational seed laser power output level; and performing a first optical alignment process to the MOPA system while the pumping power input is at the operational pumping power input level, the seed laser power output is at the first level, and the MOPA system reaches a steady operational thermal state.

The invention is optical configurations for constructing laser oscillators or laser amplifiers that comprise an extremely short fiber (typically tens of cm long or below, e.g. 5 cm to 30 cm). In order to overcome the absorption limitation due to the very short length of the fiber, the present invention employs a multi pump-pass scheme for pump light confinement. This scheme is based on the small angular overlap between the lasing and pump beams. The multi pump-pass method of the invention leads to efficient fiber laser oscillators and amplifiers having pulse duration of a few ns, with high average and peak power output that is comparable to the state-of-the-art solid state lasers.

A laser system is described, the laser system comprising: an optical cavity defined by at least first and second at least partially reflecting elements; and a gain system. The gain system comprising at least first and second gain media located within the optical cavity. The first and second gain media are configured to generate optical radiation of at least first and second wavelength ranges in response to pumping energy.

A fractional handpiece and systems thereof for skin treatment including a handpiece body including a passively Q-switched laser assembly within the handpiece body operatively connected to a pump laser source to receive a pump laser beam having a first wavelength and a beam scanning system operable to scan a solid beam emitted by the passively Q-switched laser assembly and form a line of micro-beams across a segment of skin. The passively Q-switched laser assembly generates a high-power sub-nanosecond pulsed laser beam having a second wavelength. The pump laser source is a diode laser which emits the first wavelength at about 500 nm to about 1000 nm.

A fractional handpiece and systems thereof for skin treatment including a handpiece body including a passively Q-switched laser assembly within the handpiece body operatively connected to a pump laser source to receive a pump laser beam having a first wavelength and a beam scanning system operable to scan a solid beam emitted by the passively Q-switched laser assembly and form a line of micro-beams across a segment of skin. The passively Q-switched laser assembly generates a high-power sub-nanosecond pulsed laser beam having a second wavelength. The pump laser source is a diode laser which emits the first wavelength at about 500 nm to about 1000 nm.

Disclosed is an injected laser including an optical amplifying medium arranged inside a triggered laser cavity, the optical amplifying medium having a spectral amplifying band. The injected laser includes an optical phase-modulation device, arranged between the injection source and the laser cavity, the optical phase-modulation device being configured to periodically modulate as a function of time a phase of the monochromatic continuous laser radiation at a modulation frequency equal to a natural integer multiple of the free spectral range of the laser cavity, so that the phase-modulated injection source generates a polychromatic injection radiation.

A laser device includes a gain medium configured to receive an excitation light and emit a fluorescence signal based on an amount of stored excitation light accumulated in the gain medium. The laser device includes a pump source configured to pump the excitation light to the gain medium using a supply voltage. The laser device includes one or more photodetectors configured to detect the fluorescence signal. The laser device also includes a comparator configured to generate an alert signal indicating an intensity of the detected fluorescence signal is greater than a threshold. The alert signal can trigger certain actions to occur for disrupting a destructive lasing action including one or more of ceasing output of the supply voltage to the pump source, spoiling an optical cavity to obstruct lasing action through the gain medium, or inserting a seed light to extract gain from the gain medium in a non-destructive manner.

An apparatus and method are provided for producing an ultrashort pulsed output beam. A 694 nm pump beam from a first GaN semiconductor laser diode pumped, Q-switched ruby laser is directed into at least one amplifier that includes a broadband gain element doped with trivalent chromium ions (Cr.sup.3+). A spectrally linearly chirped low-intensity seed pulse from a master oscillator is directed into the at least one optically pumped amplifier to produce an amplified linear chirped pulsed output beam. A 694 nm second pump beam from a second GaN semiconductor laser diode pumped, Q-switched ruby laser is directed into a power amplifier that also includes a broadband gain element doped with trivalent chromium ions (Cr.sup.3+). The amplified linear chirped pulsed output beam is directed into the optically pumped power amplifier to produce a high energy linear chirped pulsed output beam which is then directed into a pulse compressor to produce the ultrashort pulsed output beam.

A multi-wavelength mid-infrared laser pulse train cavity dumped laser based on Nd:MgO:APLN crystal is disclosed. In response to the needs in the field of differential absorption lidar, it is necessary to introduce multi-fundamental frequency light pulse accumulation and superposition, and parametric light synchronization pulse compression technology in the multi-wavelength mid-infrared laser operating mechanism. To this end, a splayed parametric light oscillation cavity formed in conjunction with a Nd:MgO:APLN crystal is disclosed, wherein it is possible to obtain multi-wavelength mid-infrared laser pulse train output with narrow pulse width and high peak power, meeting the needs of differential absorption lidar for mid-infrared lasers.

A multi-wavelength mid-infrared laser pulse train cavity dumped laser based on Nd:MgO:APLN crystal is disclosed. In response to the needs in the field of differential absorption lidar, it is necessary to introduce multi-fundamental frequency light pulse accumulation and superposition, and parametric light synchronization pulse compression technology in the multi-wavelength mid-infrared laser operating mechanism. To this end, a splayed parametric light oscillation cavity formed in conjunction with a Nd:MgO:APLN crystal is disclosed, wherein it is possible to obtain multi-wavelength mid-infrared laser pulse train output with narrow pulse width and high peak power, meeting the needs of differential absorption lidar for mid-infrared lasers.