The present invention provides a blue laser transmitter operating at the H-beta Fraunhofer line at 486.13 nm wavelength. The subject blue laser is based on pulsed lasing action in thulium doped into lutetium sesquioxide (Tm:Lu.sub.2O.sub.3). The laser wavelength is restricted by volume

Bragg grating to the vicinity of 1944 nm wavelength. The laser is operated with a q-switch to generate high-energy pulses within the nanosecond regime. The output at the 1944 nm wavelength is then frequency quadrupled in a single pass through non-linear crystals to a wavelength near the center of the H-beta Fraunhofer line. The operation at the 1944 nm wavelength in Tm:Lu.sub.2O.sub.3 is very efficient because this wavelength is located on a shoulder of a substantially broad emission peak at 1945 nm. In addition, at the 1944 nm wavelength, Tm:Lu.sub.2O.sub.3 has only a modest saturation fluence of about 15 J/cm.sup.2, which allows for efficient energy extraction.

The present disclosure discloses a miniaturized MOPA structure DPSSL (Diode Pumped Solid State Laser), which comprises a laser oscillator module and a laser amplifier module. The laser oscillator module consists of a seed laser and its collimating system, and the laser amplifier module consists of a laser pump module and a laser gain element. The seed laser with high beam quality is collimated by collimation system, then input into the gain element; the pump laser is pumped into the gain element via end pump or side pump mode. The seed laser beam transmits into the gain medium and is reflected by the interface several times with the “Zigzag” path, which makes the seed laser fully gained and amplified, finally achieving high power and high beam quality laser output.

In this present disclosure, the laser gain material is doped with different rare-earth ion concentrations and processed into different shapes. Some polishing surfaces of the gain material are deposited with different coatings including HR coating and AR coating, on the one hand, to improve the absorption efficiency of the pump laser, on the other hand, to make the seeds laser in the gain element achieve longer transmission distance by Zigzag transmission path, so that the energy in the gain medium can be fully extracted. And finally, achieve high power laser output.

The present disclosure can adopt the host material doped at least at the same time with Er and Yb elements as the laser gain medium, adopt high-quality 1.55-micron or other medium emission peak band seed laser source as well as end or side pump mode, and can realize the laser output with high power and high beam quality.

Compared with the MOPA laser of the prior art, the present disclosure has the advantages of simple structure, small volume, and low cost.

An Nd.sup.3+ optical fiber laser and amplifier operating in the wavelength range from 1300 to 1450 nm is described. The fiber includes a rare earth doped optical amplifier or laser operating within this wavelength band is based upon an optical fiber that guides light in this wavelength band. The waveguide structure attenuates light in the wavelength range from 850 nm to 950 nm and from 1050 nm to 1150 nm.

Low wavelength infrared Super Continuum (SC) signals from a master oscillator seeds an amplifier that supports the Raman effect. Counter-propagating, high-power, continuous wave, and quasi-continuous wave quantum cascade lasers pumps (amplify) the optical seeds forming multiple coherent wavelength optical pump sources.

A high average and peak power single transverse mode laser system is operative to output ultrashort single mode (SM) pulses in femtosecond-, picosecond- or nanosecond-pulse duration range at a kW to MW peak power level. The disclosed system deploys master oscillator power amplifier configuration (MOPA) including a SM fiber seed, outputting a pulsed signal beam at or near 1030 nm wavelength, and a Yb crystal booster. The booster is end-pumped by a pump beam output from a SM or low-mode CW fiber laser at a pump wavelength in a 1000-1020 nm wavelength range so that the signal and pump wavelengths are selected to have an ultra-low-quantum defect of less than 3%.

A low wavelength infrared Super Continuum (SC) signal from a master oscillator introduces two or more seeds into an amplifier that supports the Raman effect. A counter-propagating, high-power, continuous wave, or quasi-continuous wave quantum cascade lasers pump (amplifies) a first optical seed creating a cascading amplification of subsequent optical seeds forming two or more tunable wavelength coherent optical pump sources.

An erbium fiber laser produces a beam of ultrashort laser pulses having a center wavelength greater than 780 nanometers, an average power greater than 0.5 watt, and a pulse duration less than 200 femtoseconds. The fiber laser includes an erbium fiber amplifier that is energized by a pump beam having a pump wavelength longer than 1520 nanometers. The pump wavelength is selected to provide uniform gain over the broad spectral bandwidth of a seed beam and minimal gain at shorter wavelengths in the fiber amplifier, thereby overcoming gain narrowing and gain shifting. The pump beam has sufficient power to achieve pump saturation in the fiber amplifier.

An erbium fiber laser produces a beam of ultrashort laser pulses having a center wavelength greater than 780 nanometers, an average power greater than 0.5 watt, and a spectral bandwidth compressible to a pulse duration of less than 200 femtoseconds. The laser includes a fiber preamplifier that is energized by a counter-propagating pump beam, has relatively low population inversion in a relatively long optical gain fiber, and provides a spectrally-shaped beam for further amplification. Wavelength dependent gain and absorption within the optical gain fiber enhances longer wavelengths relative to shorter wavelengths in the spectrally-shaped beam. The spectral shaping is sufficient to overcome gain narrowing and gain shifting in a subsequent high-gain fiber amplifier.

An opposing pump structure for twin 980-nm pump lasers in an EDFA, the structure comprising erbium-doped optical fiber, two 980-nm pump lasers, two signal/pump combiners, and anti-interference structures. Two 980-nm pump lasers output first pump light and second pump light, respectively, and first pump light and second pump light are injected into erbium-doped optical fiber in forward direction and reverse direction, respectively. Optical transmission path of first pump light and optical transmission path of second pump light are separately provided with anti-interference structures. Anti-interference structures are two fiber Bragg gratings or two optical filters. The invention improves optical paths of opposing pump structure for twin 980-nm pump lasers, and adds fiber Bragg gratings or optical filters to serve as anti-interference structures, so as to prevent residual pump light from either direction from entering opposite direction, thereby eliminating mutual interference between two opposing 980-nm pumps, and avoiding damage to tube cores.

A laser device includes a light source device including a semiconductor laser; and a laser cavity irradiated with light from the light source device and including a saturable absorber. A beam waist diameter r of the light that irradiates the laser cavity and an initial transmittance T.sub.0 of the saturable absorber satisfy a relationship of 7.75T.sub.0.sup.47.77T.sub.0.sup.3+3.13T.sub.0.sup.2+0.16T.sub.0+0.74r2.62T.sub.0+0.675.