A compound represented by the formula (1) has excellent lasing properties. G.sup.1 and G.sup.2 are H or substituent; FL.sup.1 and FL.sup.2 are represented by the formula (2); BT is represented by the formula (4); and n1, n2 and m are 1 to 5.

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A compound represented by the formula (1) has excellent lasing properties. G.sup.1 and G.sup.2 are H or substituent; FL.sup.1 and FL.sup.2 are represented by the formula (2); BT is represented by the formula (4); and n1, n2 and m are 1 to 5.

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Disclosed is a femtosecond laser device. The femtosecond laser device includes a pulse oscillator configured to generate a laser pulse, a pulse width stretcher configured to stretch a width of the laser pulse, a pulse width compressor connected to the pulse width stretcher to compress the width of the laser pulse, a pulse amplifier disposed between the pulse width compressor and the pulse width stretcher to amplifier an intensity of the laser pulse, and a nonlinear pulse attenuator including an optical fiber connected between the pulse width amplifier and the pulse width stretcher and deformed to have a spiral shape, a stretched length, or a twist.

An optical oscillator includes a first reflection part configured to reflect light of a first wavelength, a laser medium excited by excitation light of a second wavelength different from the first wavelength and configured to emit light of the first wavelength, a second reflection part configured to form an unstable resonator together with the first reflection part, the unstable resonator being configured to output annular laser light of the first wavelength, and a saturable absorption part disposed between the laser medium and the second reflection part and of which a transmittance increases with absorption of light of the first wavelength. When a power of the excitation light is indicated by P.sub.p (kW), and an inner diameter of the annular laser light is indicated by d.sub.i, and an outer diameter is indicated by d.sub.o, and d.sub.o/d.sub.i is a magnification m, the magnification m satisfies a.sub.0+a.sub.1 Log(P.sub.p)≤m≤b.sub.0+b.sub.1P.sub.p+b.sub.2P.sub.p.sup.2.

A gain mirror is created for use as an optical amplifier in a solid state ring laser rotation sensor. Such a ring laser includes at least three mirrors for reflecting counter propagating laser beams around a closed loop optical path, wherein at least one of the mirrors is a gain mirror. The gain mirror is formed by applying a thin film of silica, a few half wavelengths thick and doped with Nd isotopes, onto a very high reflectivity mirror and then using a laser diode to pump it with intense light to form a population inversion in Nd.sup.3+ ions. An assembly consisting of this gain mirror and a pump laser diode can be used as an optical amplifier in a solid state ring laser to generate the two counter propagating laser light beams needed to measure rotation.

A distributed gain polygon ring laser system includes a substrate ring, top and bottom cover plates, an input pump laser, an output coupler and a number of reflection points. The substrate ring has inner and outer surfaces. The top and bottom cover plates are configured for vacuum sealing with the substrate ring. The input pump laser is configured to direct light into the substrate ring. The plurality of reflection points are spaced around the inner surface of the substrate ring and are configured to reflect light from the input pump laser to the output coupler in a series of reflections.

A lidar device, comprising a laser generator and a lidar unit, is provided and operated with frequency modulation continuous wave. The laser generator comprises an amplifier unit; and a reflector unit connected with at least one end of the amplifier unit. The amplifier unit comprises at least one first luminous gain area and at least one second luminous gain area. The first luminous gain area is operated in a saturated region with a first current source applied. The second luminous gain area is operated in a linear region with a second current source applied. Thus, a laser is generated and outputted to the lidar unit. The laser generator is operated with the luminous gain areas of the amplifier unit pushed into the saturated region to suppress intensity modulation and fix power. Even if current changes, frequency drifts only with continuity and adjustability achieved and no mode hop happened.

A laser ablation apparatus includes: a laser beam generator including beam sources for generating laser beams, the laser beam generator using a solid-state laser; an output beam generator for generating an output beam using the laser beams; and a substrate stage including at least one stage on which a carrier substrate formed on the front of a panel substrate is disposed. The output beam generator may include: mixers for generating mixed laser beams having two linear-polarizations orthogonal to each other by mixing the laser beams; and a photo molding machine for generating the output beam using the mixed laser beams.

A short-pulse, narrowband, line-selectable and tunable solid-state laser is described. The device requires a pump source, an active solid-state laser medium, an enclosing cavity, mirrors to contain the light, a method of removing the pulse from the cavity, a wavelength selection system, and a laser linewidth narrowing system. One implementation of this is an Er:YAG laser, side pumped by semiconductor lasers in the erbium absorption band near 1475 nm, with an intracavity etalon and a switchable spectral filter. To remove the pulse from the cavity, cavity dumping issues, which assures constant pulse energy and pulse length over a range of repetition rates, in this case from 100 Hz to 20 kHz. Line selection is obtained by use of wavelength filters and fine tuning with an etalon, which also acts as the linewidth narrowing system.

A technique which is suitable in joining an end surface of a laser medium to a transparent heat sink for maintaining thermal resistance therebetween low and avoiding large thermal stress from acting on the laser medium is to be provided. An end coat is provided on the end surface of the laser medium, a same-material layer constituted of a same material as the heat sink is provided on a surface of the end coat, a surface of the same-material layer and an end surface of the heat sink are activated in a substantially vacuum environment, and those activated surfaces are bonded in the substantially vacuum environment. A laser apparatus having low thermal resistance between the laser medium and the heat sink and high transparency at a joint interface therebetween, and no large thermal stress acting on the laser medium is thereby obtained.