The present invention discloses a transverse mode switchable all-fiber high-order mode Brillouin laser. The laser comprises a narrow linewidth pump laser, an optical amplifier, a 1×N optical switch (N≥2), a fiber mode selection coupler group, a first polarization controller, a fiber circulator, a fiber coupler, a second polarization controller, and a few-mode fiber. Based on the Brillouin nonlinear gain of a few-mode fiber in a ring cavity, the present invention realizes the resonance amplification of a specific order transverse mode in the cavity, and obtains the transverse mode switchable high-order mode laser beam output. The present invention, adopting an all-fiber structure, has the advantages of simple structure, low cost, easy fiber system integration, high stability and narrow linewidth of outputted laser beams, etc., and improves the practicality and reliability of high-order mode lasers.

A pump light source includes a light emitting unit, a mode converter, and an optical interface unit. The light emitting unit is configured to output multi-mode pump light. The mode converter is configured to convert the multi-mode pump light output by the light emitting unit into a plurality of channels of single-mode pump light and output the plurality of channels of single-mode pump light. The optical interface unit is connected to an optical amplifier via an optical transmission medium to provide at least one channel of single-mode pump light in the plurality of channels of single-mode pump light for a corresponding optical amplifier via the optical transmission medium.

The inventive Device is comprising a laser rangefinder for determining the distance along a laser axis between the device and a target object. The laser rangefinder is comprising a pumping laser and a thulium and/or holmium doped fiber laser with a thulium and/or holmium doped fiber section and two Bragg gratings arranged on both sides of the thulium and/or holmium doped fiber section of the thulium and/or holmium doped fiber laser wherein the thulium and/or holmium doped fiber laser is pumped by the pumping laser and configured to emit laser light with a wavelength in the range of 1900 nm to 2150 nm. The inventive device has an improved applicability.

A single longitudinal mode ring Raman laser including: a pump source outputting a pump light power, resonantly coupled to a first ring resonator; a optical measurement and piezo-actuator for stabilising the resonant coupling of the pump light power to a first ring resonator; a first ring resonator including a Raman gain medium, wherein the Raman gain medium receives the pump light power and undergoes Raman lasing generating resonated Stokes power at the corresponding Stokes output wavelength; the first ring resonator acting as a feedback loop for the pump light power and the resonated Stokes power and outputting a portion of the Stokes power as the laser output.

The present invention provides a repetition frequency-tunable optical frequency comb generated by basis of optical feedback. The optical frequency comb comprises a single-frequency laser resonant cavity, a wavelength division multiplexer, a single-mode semiconductor pump light source, an optical circulator, a first optical fiber coupler, a second optical fiber coupler, a photoelectric detector, a highly-stable signal source, an error signal processing system, a laser frequency modulation device and a tunable laser-delay module. The present invention performs delay-time processing to the single-frequency laser by the tunable laser-delay module, and achieves an optical feedback by the optical circulator for injecting to the resonant cavity, generating a series of tunable laser longitudinal modes with equal frequency space. Meanwhile, in combination with the highly-stable signal source, the error signal processing system and the laser frequency modulation device, a laser frequency lock is achieved, and the laser frequency comb is generated. The invention obtains a repetition frequency-tunable laser frequency comb with a simple and practical method, having an extensive application prospect and huge application value in fields such as optical fiber sensing and spectroscopy of atom and molecule.

The present invention discloses a transverse mode switchable all-fiber high-order mode Brillouin laser. The laser comprises a narrow linewidth pump laser, an optical amplifier, a 1N optical switch (N2), a fiber mode selection coupler group, a first polarization controller, a fiber circulator, a fiber coupler, a second polarization controller, and a few-mode fiber. Based on the Brillouin nonlinear gain of a few-mode fiber in a ring cavity, the present invention realizes the resonance amplification of a specific order transverse mode in the cavity, and obtains the transverse mode switchable high-order mode laser beam output. The present invention, adopting an all-fiber structure, has the advantages of simple structure, low cost, easy fiber system integration, high stability and narrow linewidth of outputted laser beams, etc., and improves the practicality and reliability of high-order mode lasers.

The inventive Device is comprising a laser rangefinder for determining the distance along a laser axis between the device and a target object. The laser rangefinder is comprising a pumping laser and a thulium and/or holmium doped fiber laser with a thulium and/or holmium doped fiber section and two Bragg gratings arranged on both sides of the thulium and/or holmium doped fiber section of the thulium and/or holmium doped fiber laser wherein the thulium and/or holmium doped fiber laser is pumped by the pumping laser and configured to emit laser light with a wavelength in the range of 1900 nm to 2150 nm. The inventive device has an improved applicability.

A manufacturing technique of ultra-wideband high gain optical fibers and devices is disclosed, including: (1) manufacturing a gain fiber, which is a composite structural optical fiber, having a core composed of a plurality of sets of sector structures distributed symmetrically or a plurality of concentric ring structures. The core is composed of at least two kinds of rare-earth-ion-doped glass, and luminescence centers are located in different sector or ring structure regions; and (2) constructing a fiber laser: using the gain fiber, selectively exciting rare earth ions in different regions in the core by controlling a shape of pump light spot, and combining with fiber grating pairs to realize a tunable laser output. The present disclosure can manufacture gain fibers with high-gain and ultra-wideband characteristics by combining the design of the fiber structure and the control of the light field of the pump light.

Embodiments of this application provide an optical power adjustment system and an optical power adjustment apparatus. The system includes a multi-mode light source, a mode demultiplexer, and an optical power adjustment apparatus. The multi-mode light source is configured to output a multi-mode optical signal, where the multi-mode optical signal includes N transverse-mode optical signals, N=2.sup.M, and M is an integer greater than 1. The mode demultiplexer is configured to convert the N transverse-mode optical signals into N fundamental-mode optical signals, and output the N fundamental-mode optical signals. The optical power adjustment apparatus includes M optical power adjustment modules and a control apparatus, each optical power adjustment module includes a plurality of phase shifters, and the control apparatus is electrically connected to the M optical power adjustment modules. A K.sup.th optical power adjustment module includes 2.sup.K1 multi-mode interferometers MMIs.

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%.