Apparatuses and methods are disclosed for applying laser energy having desired pulse characteristics, including a sufficiently short duration and/or a sufficiently high energy for the photomechanical treatment of skin pigmentations and pigmented lesions, both naturally-occurring (e.g., birthmarks), as well as artificial (e.g., tattoos). The laser energy may be generated with an apparatus having a resonator with a sub-nanosecond round trip time.

The laser device includes a laser crystal, a resonator including a pair of mirrors between which the laser crystal is interposed, a Q switch that is disposed on an optical path of the resonator and controls a Q value of the resonator, and a Brewster thin-film polarizer that is disposed on the optical path of the resonator and transmits selectively p-polarized light. The thin-film polarizer has wavelength selectivity in which a p-polarized light transmittance at a first wavelength exhibiting a maximum gain of the laser crystal is 5% or more to 25% or less, the p-polarized light transmittance monotonically increases as a wavelength becomes longer than the first wavelength, and a maximum transmittance is exhibited at a third wavelength. The laser device oscillates laser light at a second wavelength that is a wavelength longer than the first wavelength and shorter than or equal to the third wavelength.

A laser for high power applications. The laser is a lamp driven slab design with a face to face beam propagation scheme and an end reflection that redirects the amplified radiation back out the same input surface. Also presented is a side to side larger amplifier configuration, permitting very high average and peak powers due to the electrical efficiency of absorbing energy into the crystal, optical extraction efficiency, and scalability of device architecture. Cavity filters adjacent to pump lamps convert the unusable UV portion of the pump lamp spectrum into light in the absorption band of the slab laser thereby increasing the overall pump efficiency. The angle of the end reflecting surface is changed to cause the exit beam to be at a different angle than the inlet beam, thereby eliminating the costly need to separate the beams external to the laser with the subsequent loss of power.

A laser for high power applications. The laser is a lamp driven slab design with a face to face beam propagation scheme and an end reflection that redirects the amplified radiation back out the same input surface. Also presented is a side to side larger amplifier configuration, permitting very high average and peak powers due to the electrical efficiency of absorbing energy into the crystal, optical extraction efficiency, and scalability of device architecture. Cavity filters adjacent to pump lamps convert the unusable UV portion of the pump lamp spectrum into light in the absorption band of the slab laser thereby increasing the overall pump efficiency. The angle of the end reflecting surface is changed to cause the exit beam to be at a different angle than the inlet beam, thereby eliminating the costly need to separate the beams external to the laser with the subsequent loss of power.

Methods, systems and apparatus are disclosed for delivery of pulsed treatment radiation by employing a pump radiation source generating picosecond pulses at a first wavelength, and a frequency-shifting resonator having a lasing medium and resonant cavity configured to receive the picosecond pulses from the pump source at the first wavelength and to emit radiation at a second wavelength in response thereto, wherein the resonant cavity of the frequency-shifting resonator has a round trip time shorter than the duration of the picosecond pulses generated by the pump radiation source. Methods, systems and apparatus are also disclosed for providing beam uniformity and a sub-harmonic resonator.

A solid-state laser device includes a laser rod made of an alexandrite crystal; a flash lamp that outputs excitation light for exciting the laser rod, a glass tube for a lamp being made of quartz glass that at least blocks deep ultraviolet light having a wavelength of 200 nm to 300 nm, and transmits visible light having a wavelength of 400 nm or more; and a laser chamber that contains a tubular reflector that includes a hole part containing at least a portion of the laser rod or a portion of the flash lamp and is made of a porous material of polytetrafluoroethylene, an inner wall surface of the hole part being as a reflecting surface that reflects the excitation light.

A solid-state laser device includes a laser rod made of an alexandrite crystal; a flash lamp that outputs excitation light for exciting the laser rod, a glass tube for a lamp being made of quartz glass that at least blocks deep ultraviolet light having a wavelength of 200 nm to 300 nm, and transmits visible light having a wavelength of 400 nm or more; and a laser chamber that contains a tubular reflector that includes a hole part containing at least a portion of the laser rod or a portion of the flash lamp and is made of a porous material of polytetrafluoroethylene, an inner wall surface of the hole part being as a reflecting surface that reflects the excitation light.

A kind of all-solid-state high-power slab laser based on phonon band-edge emission, which is comprised of a pumping source, a focusing system, a resonant cavity and a self-frequency-doubling crystal; the said self-frequency-doubling crystal is a Yb-doped RECOB crystal cut into slab shape along the direction of the crystal's maximum effective nonlinear coefficient of its non-principal plane; by changing the cutting direction of the crystal, the phase matching of different wavelengths is realized, thus realizing laser output at the band of 560-600 nm; the said pumping source is a diode laser matrix with a wavelength of 880 nm-980 nm; the input cavity mirror and the output cavity mirror are coated with films to obtain laser output at the band of 560-600 nm; the two large faces of the said self-frequency-doubling crystal is cooled by heat sink and located between the input cavity mirror and the output cavity mirror.

A kind of all-solid-state high-power slab laser based on phonon band-edge emission, which is comprised of a pumping source, a focusing system, a resonant cavity and a self-frequency-doubling crystal; the said self-frequency-doubling crystal is a Yb-doped RECOB crystal cut into slab shape along the direction of the crystal's maximum effective nonlinear coefficient of its non-principal plane; by changing the cutting direction of the crystal, the phase matching of different wavelengths is realized, thus realizing laser output at the band of 560-600 nm; the said pumping source is a diode laser matrix with a wavelength of 880 nm-980 nm; the input cavity mirror and the output cavity mirror are coated with films to obtain laser output at the band of 560-600 nm; the two large faces of the said self-frequency-doubling crystal is cooled by heat sink and located between the input cavity mirror and the output cavity mirror.

A laser system may include a controller configured to direct a plurality of temporally spaced-apart electrical pulses to a device that optically pumps a lasing medium, and a lasing medium configured to output a quasi-continuous laser pulse in response to the optical pumping. The plurality of temporally spaced-apart electrical pulses may include (a) a first electrical pulse configured to excite the lasing medium to an energy level below a lasing threshold of the lasing medium, and (b) multiple second electrical pulses following the first electrical pulse. The quasi-continuous laser pulse is output in response to the multiple second electrical pulses.