Abstract: Single mode oscillation at a wavelength of about 1064.4 nm is enabled with no use of an etalon installed in an optical resonator by providing one of two ends of a Nd:YAG element, which acts as one end of the optical resonator, with an HR coating arranged for the wavelength of about 1064.4 nm and determining the thickness along the direction of transmission of light of the Nd:YAG element so that the peak of reflection appears at the wavelength of about 1064.4 nm but not at a wavelength of about 1062.8 nm.

Abstract: A compact apparatus is provided for stably converting a wavelength of a laser diode with the use of an optical fiber and a wavelength selective device. Employing a bulk type element as a wavelength selective device makes the action of controlling the temperature of the device easy, and can stabilize the wavelength emitted from the laser diode. The optical fiber (2) is placed between the output side of a laser diode (1) and a wavelength selective device (5) of bulk type. While the optical fiber (2) is arranged compact in the form of a coil, the length of an extra-cavity defined by the wavelength selective device (5) is sufficiently longer than the coherence length. Accordingly, the action of stably converting the wavelength can be carried out by the compact apparatus.

Abstract: Single mode oscillation at a wavelength of about 1064.4 nm is enabled with no use of an etalon installed in an optical resonator by providing one of two ends of a Nd:YAG element, which acts as one end of the optical resonator, with an HR coating arranged for the wavelength of about 1064.4 nm and determining the thickness along the direction of transmission of light of the Nd:YAG element so that the peak of reflection appears at the wavelength of about 1064.4 nm but not at a wavelength of about 1062.8 nm.

Abstract: A solid laser apparatus has either a combination of a lowpass filter (9c) and a highpass filter (9d) or a bandpass filter 9f provided in its output control circuit (8, 9, 10) for increasing the gain and adjusting the phase of a signal in the vicinity of the relaxation oscillating frequency. Also, a solid laser apparatus has the phase shift circuit (9g) provided in its output control circuit (8,9,10) for advancing the phase of a signal in the vicinity of the relaxation oscillating frequency thereof. Moreover, a solid laser apparatus has a pseudo notch filter (9h), which is arranged for the gain to have a local minimum at the relaxation oscillating frequency of the solid laser apparatus, provided in the output control circuit (8,9,10) so that the peak of the gain transmission characteristic of the nonlinear optical device (4) or of a combination of the nonlinear optical device (4) and the microchip laser crystal (3) is offset.

Abstract: A solid laser apparatus has either a combination of a lowpass filter and a highpass filter or a bandpass filter provided in its output control circuit for increasing the gain and adjusting the phase of a signal in the vicinity of the relaxation oscillating frequency. Also, a solid laser apparatus has the phase shift circuit provided in its output control circuit for advancing the phase of a signal in the vicinity of the relaxation oscillating frequency thereof. Moreover, a solid laser apparatus has a pseudo notch filter, which is arranged for the gain to have a local minimum at the relaxation oscillating frequency of the solid laser apparatus, provided in the output control circuit so that the peak of the gain transmission characteristic of the nonlinear optical device or of a combination of the nonlinear optical device and the microchip laser crystal is offset.

Abstract: A grating is provided in an optical fiber for adjusting the wavelength of an output light from the optical resonator which consists mainly of a semiconductor light emitting device and the optical fiber to be slightly shorter than a wavelength range of an input light where the wavelength range of an input light can be converted by a wavelength conversion device. As the grating is adjustably expanded with a knob control being turned, the wavelength of the output light from the optical resonator is modified to be matched with the wavelength range of the input light where the wavelength of the input light can be converted by the wavelength conversion device.

Abstract: A solid state laser medium is composed of Nd:YAG, the wavelength of a second harmonic wave is 557 to 559 nm and a free spectral range of a solid etalon falls in any of the values of a range A of 1.04 to 1.07 nm, a range B of 1.42 to 1.61 nm, a range C of 2.07 to 2.14 nm and a range D of 2.37 to 3.21 nm.

Abstract: A solid laser apparatus has a wavelength converter temperature controller 40 arranged for driving a Peltier device 41 to control the temperature Tc of a wavelength converter 5 so that the acceptable wavelength range of the wavelength converter 5 adapts to the wavelength range of reflected light from the grating part 6 at the temperature Ti and a laser controller 60 arranged for driving a semiconductor light amplifier device 1 to maintain the intensity of the extraordinary component passed through the polarizer 52 and measured by a photometer device 57.

Abstract: A solid laser apparatus has either a combination of a lowpass filter (9c) and a highpass filter (9d) or a bandpass filter 9f provided in its output control circuit (8, 9, 10) for increasing the gain and adjusting the phase of a signal in the vicinity of the relaxation oscillating frequency. Also, a solid laser apparatus has the phase shift circuit (9g) provided in its output control circuit (8,9,10) for advancing the phase of a signal in the vicinity of the relaxation oscillating frequency thereof. Moreover, a solid laser apparatus has a pseudo notch filter (9h), which is arranged for the gain to have a local minimum at the relaxation oscillating frequency of the solid laser apparatus, provided in the output control circuit (8,9,10) so that the peak of the gain transmission characteristic of the nonlinear optical device (4) or of a combination of the nonlinear optical device (4) and the microchip laser crystal (3) is offset.

Abstract: A solid laser apparatus is provided comprising a semiconductor light emitter 1, an optical fiber 3 having a grating part 6 provided therein, and a wavelength converter 5 for receiving an input of light from an optical resonator composed of the semiconductor light emitter 1 and the optical fiber 3 and releasing its harmonic light, wherein the distance D between the grating part 6 and the wavelength converter 5 is equal to or greater than ½ of the coherent length of the input light.

Abstract: A solid laser apparatus has a wavelength converter temperature controller 40 arranged for driving a Peltier device 41 to control the temperature Tc of a wavelength converter 5 so that the acceptable wavelength range of the wavelength converter 5 adapts to the wavelength range of reflected light from the grating part 6 at the temperature Ti and a laser controller 60 arranged for driving a semiconductor light amplifier device 1 to maintain the intensity of the extraordinary component passed through the polarizer 52 and measured by a photometer device 57.

Abstract: A solid laser apparatus is provided comprising a semiconductor light emitter 1, an optical fiber 3 having a grating part 6 provided therein, and awavelength converter 5 for receiving an input of light from an optical resonator composed of the semiconductor light emitter 1 and the optical fiber 3 and releasing its harmonic light, wherein the distance D between the grating part 6 and the wavelength converter 5 is equal to or greater than ½ of the coherent length of the input light.

Abstract: A solid laser apparatus has either a combination of a lowpass filter and a highpass filter or a bandpass filter provided in its output control circuit for increasing the gain and adjusting the phase of a signal in the vicinity of the relaxation oscillating frequency. Also, a solid laser apparatus has the phase shift circuit provided in its output control circuit for advancing the phase of a signal in the vicinity of the relaxation oscillating frequency thereof. Moreover, a solid laser apparatus has a pseudo notch filter, which is arranged for the gain to have a local minimum at the relaxation oscillating frequency of the solid laser apparatus, provided in the output control circuit so that the peak of the gain transmission characteristic of the nonlinear optical device or of a combination of the nonlinear optical device and the microchip laser crystal is offset.

Abstract: A grating is provided in an optical fiber for adjusting the wavelength of an output light from the optical resonator which consists mainly of a semiconductor light emitting device and the optical fiber to be slightly shorter than a wavelength range of an input light where the wavelength range of an input light can be converted by a wavelength conversion device. As the grating is adjustably expanded with a knob control being turned, the wavelength of the output light from the optical resonator is modified to be matched with the wavelength range of the input light where the wavelength of the input light can be converted by the wavelength conversion device.