The present disclosure discloses a degassing-free underwater dissolved carbon dioxide detection device and a detection method. The degassing-free underwater dissolved carbon dioxide detection device includes a computer, which is used to provide the driving signal and controlling parameters for the power tuning unit; the computer is connected with a laser driving control module and the power tuning unit, respectively; the laser driving control module is connected with a laser; the laser is connected with a photo-isolator; the photo-isolator is connected with a thulium-doped fiber vertical-cavity laser system; the thulium-doped fiber vertical-cavity laser system is connected with a photoacoustic cell system through a fiber collimator; the photoacoustic cell system is connected with a pre-amplifier circuit and a lock-in amplifier in sequence, and the lock-in amplifier is connected with the computer.

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.

An optical fiber amplification. system includes: a first optical fiber amplifier including a first optical amplifying fiber including a core portion doped with a first rare-earth. element, a first input unit configured to receive first signal light, an excitation-light source configured to output pump light, a pump light combiner configured to input the pump light to the first optical amplifying fiber, and a residual pump light recovery device configured to recover residual pump light; and a second optical fiber amplifier including a second optical amplifying fiber including a core portion doped with a second rare-earth. element, a second input unit configured to receive second signal light, and a residual pump light combiner configured to input, to the second optical amplifying fiber, the residual pump light recovered by the residual pump light recovery device.

An optical fiber configured to improve the pump conversion efficiency of an L-band fiber amplifier which uses the multimode pump source. By directly absorbing multimode light including 915 nm, an active fiber core region co-doped with both erbium and ytterbium can provide gain to the L-band signals via stimulated emission. The unwanted C-band amplified spontaneous emission (ASE) light generate from this active fiber core region can be absorbed by another active fiber core region doped with erbium, then provides additional gain to the L-band signals. Active regions and cladding can be configured to match a given spatial mode of the optical signal. Signal-pump combiners with end-coupling or side coupling can be used.

An injection locking laser source is provided for an optical communications system. The injection locking laser source includes a laser cavity configured to receive an externally injected low linewidth primary light source. The laser cavity includes a cavity length, a cavity facet reflectivity, and a cavity quality factor. The injection locking laser source further includes an emitting region configured to output a secondary light source injection locked to the externally injected low linewidth primary light source at a stable detuning frequency based on a photon number, a steady-state phase, and a carrier number of the primary light source injected into the cavity.

An apparatus may include a diode-pumped solid-state laser oscillator configured to output a pulsed laser beam, a modulator configured to modify an energy and a temporal profile of the pulsed laser beam, and an amplifier configured to amplify an energy of the pulse laser beam. A modified and amplified beam to laser peen a target part may have an energy of about 5J to about 10 J, an average power (defined as energy (J) x frequency (Hz)) of from about 25 W to about 200 W, with a flattop beam uniformity of less than about 0.2. The diode-pumped solid-state oscillator may be configured to output a beam having both a single longitudinal mode and a single transverse mode, and to produce and output beams at a frequency of about 20 Hz.

A laser medium unit 10 in a laser beam amplification device includes a plurality of laser media 14. A cooling medium flow path F1 is provided around the laser medium unit 10 to cool the laser medium unit 10 from outside. A sealed space between the laser media 14 is filled with gas or liquid, and a laser beam for passing through the sealed space is not interfered by a cooling medium flowing outside. Therefore, a fluctuation of an amplified laser beam is prevented, and a quality such as stability and focusing characteristics of the laser beam is improved.

A highly efficient laser ignition device is provided. The highly efficient laser ignition device fundamentally includes: a pumping light source adopting a multi-chip single emitter-packaged optical fiber output laser diode; a laser medium to which ytterbium is added; and a saturated absorber as a passive Q-switch medium, wherein a pulse of 100-999 ps as the passive Q-switch laser output can be obtained. According to the disclosed, the problems of high cost/low efficiency/low reliance/non-uniformity, which are disadvantages for replacing an ignition device using an electric spark with a laser ignition device, can be solved.

A laser amplifier device including an amplification element which includes a solid-state gain medium including a first main face and a second main face separated from each other by a distance which is smaller than the lateral dimensions. A heat spreader is thermally connected to, and substantially covering, the first main face. The heat spreader is optically transparent to a pump light and is in thermal contact with a heat sink. A first reflector substantially covers and faces the first main face and a second reflector substantially covers and faces the second main face; the reflectors being configured to reflect the pump light. The heat spreader and the first reflector are arranged such that the pump light passes through the heat spreader and through the first reflector and is reflected multiple times across the amplification element, between the first and second reflectors.

An optical fiber amplification apparatus is disclosed, including an optical receiving port, a first optical output port, a second optical output port, a gain medium, a pump laser, reflection films, and a transmission-reflection film. The pump laser activates a function of the gain medium to amplify an optical signal. A multiplexed optical signal including a first-waveband optical signal and a second-waveband optical signal is incident onto the gain medium. The reflection films enable the multiplexed optical signal to be reflected back and forth in the gain medium. After the first-waveband optical signal reaches a first target gain, the first-waveband optical signal is output from the gain medium to the first optical output port. The second-waveband optical signal is amplified in the gain medium. After the second-waveband optical signal reaches a second target gain, the second-waveband optical signal is output from the gain medium to the second optical output port.