Optical gain mediums are required for lasing devices and high intensity optical systems across a wide range of applications. A method for achieving optical gain includes an optical gain medium having colloidal quantum fountains includes providing pump radiation to the gain medium. The electrons of the colloidal quantum fountains are promoted from a valence band to an excited state in a conduction band of the colloidal quantum fountains. Seed radiation is provided to the gain medium and electrons of the quantum fountains are de-excited by the seed radiation through stimulated emission from the excited state to a lower energy state of the conduction band, thereby providing optical gain.

A fluid-cooled laser amplifier module (100) is disclosed which comprises: a casing; a plurality of slabs (110) of optical gain medium oriented in parallel in the casing for cooling by a fluid stream (154, 156); a polarisation rotator (120) disposed between a first group of one or more slabs (111) of the optical gain medium and a second group of one or more slabs (112) of the optical gain medium; optical windows (150, 152) for receiving an input beam or pulse (130) for amplifying by the slabs and for outputting the amplified beam or pulse (140); and fluid stream ports (155, 157) for receiving and discharging the fluid stream for cooling the slabs.

A disk resonator is pumped by counterpropagating pump signals to produce corresponding counterpropagating Brillouin laser signals. The pump laser optical frequencies are separated by a frequency offset Δν.sub.P but excite the same nominal resonator optical mode; the Brillouin laser optical frequencies are separated by a beat frequency Δν.sub.L with 0<Δν.sub.L<Δν.sub.P. A photodetector receives the Brillouin laser signals and produces an electrical signal at the beat frequency Δν.sub.L. The frequency offset Δν.sub.P can be large so enough to prevent locking of the Brillouin laser signals onto a common Brillouin laser frequency. A signal processing system derives from the beat frequency Δν.sub.L an estimated angular velocity component of the disk optical resonator about an axis substantially perpendicular to the disk optical resonator.

A multi-wavelength laser device equipped with a linear cavity along which a first direction and a second direction opposite to the first direction are defined is disclosed. The apparatus includes, along the first direction, a first optical component, a gain and Raman medium, a sum frequency generation crystal, a first second-harmonic generation crystal and a second optical component. The first optical component allows a pumping light to transmit therethrough and be incident in the first direction. The gain and Raman medium receives the pumping light from the first optical component and generates a first infrared base laser light having a first wavelength and a second infrared base laser light having a second wavelength. The first and second optical components form a laser cavity for oscillation of these two infrared base laser lights. The sum frequency generation crystal receives the first and second infrared base laser lights and generates a first visible laser light having a third wavelength. The first second-harmonic generation crystal receives the first infrared base laser light and generates a second visible laser light having a fourth wavelength. The second optical element allows the first and the second visible laser lights to emit out along the first direction.

A laser system and method generate milliwatt-power pump light by a fiber-coupled laser diode with a single-mode integrated fiber housed in a pump enclosure. The milliwatt-power pump light is conveyed from the single-mode integrated fiber out of the first enclosure into one end of a single-mode fiber cable that is external to the pump enclosure. The milliwatt-power pump light is conveyed from an opposite end of the external single-mode fiber cable into one end of a single-mode resident fiber disposed internally within a laser-head enclosure. A crystal housed in the laser-head enclosure is pumped with the milliwatt-power pump light that exits into free space from an opposite end of the single-mode resident fiber onto a face of the crystal, to produce stable milliwatt-power single-mode laser light having a frequency stability of less than 3 MHz per minute. The stable milliwatt-power single-mode laser light is emitted from the laser-head enclosure.

A low-noise amplifier includes a gain medium and two or more amplifier stages. Each amplifier stage includes an optical filter to pass all wavelengths of a respective input optical signal in a given propagation direction over the gain medium and reflect wavelengths above a respective threshold wavelength received in the opposite direction, and a respective Raman pump to inject a pump light centered at a wavelength lower than the threshold wavelength onto the gain medium for transmission in the given direction. A first amplifier stage outputs a first combined optical signal including all wavelengths of the respective input optical signal and a pump light injected by the respective Raman pump. The second amplifier stage receives the first combined optical signal as its input and outputs a second combined optical signal including all wavelengths of the first combined optical signal and a pump light injected by the respective Raman pump.

Systems and methods for ring laser gyroscopes (RLGs) are provided. An RLG includes a traveling-wave resonator cavity with three or more mirrors and a gain medium positioned in the traveling-wave resonator cavity between two of the three or more mirrors. The gain medium is a solid-state gain medium or a nonlinear optical medium. The RLG further includes a first pump laser and a second pump laser to pump the gain medium in different directions and generate first and second lasing signals that traverse the traveling-wave resonator cavity in a opposite directions. The RLG further includes first and second photodetectors to measure levels of the first and second lasing signals. The RLG further includes at least one processor configured to adjust a power level of the first pump laser and/or a power level of the second pump laser based on the measured power levels of the first and second lasing signals.

Disclosed are a method, device and system for dynamically controlling a gain of a Raman optical fiber amplifier. The method comprises: determining whether a target gain falls within a gain mask range; if the target gain falls within the gain mask range, directly locking a gain to the target gain; and if the target gain falls outside the gain mask range, locking the gain to a corresponding maximum gain in the gain mask range, and gradually increasing the locked gain according to a preset first step length until the target gain is reached or until at least one pump laser reaches a maximum output power. The invention enables an optical fiber amplifier to respond quickly to a change in an input optical signal, ensures gain stability, and ensures that no power overshoot or undershoot occurs in the non-switched optical channels in an optical path. Moreover, the invention minimizes an amount of time required to complete switching between gains.

A multi-stage thulium-doped (Tm-doped) fiber amplifiers (TDFA) is based on the use of single-clad Tm-doped optical fiber and includes a wavelength conditioning element to compensate for the nonuniform spectral response of the initial stage(s) prior to providing power boosting in the output stage. The wavelength conditioning element, which may comprise a gain shaping filter, exhibits a wavelength-dependent response that flattens the gain profile and output power distribution of the amplified signal prior to reaching the output stage of the multi-stage TDFA. The inclusion of the wavelength conditioning element allows the operating bandwidth of the amplifier to be extended so as to encompass a large portion of the eye-safe 2 μm wavelength region.

A femtosecond pulse laser apparatus includes a pump light source configured to provide a pump light, a gain medium configured to obtain a gain of a laser light using the pump light, a first curved mirror and a second curved mirror, which are provided at both sides of the gain medium, an output mirror configured to transmit a portion of the laser light and reflect the other portion of the laser light to the gain medium, a mode locking portion configured to generate a femtosecond pulse of the laser light, and an acoustic wave generator configured to provide an acoustic wave into the gain medium so as to adjust self-phase modulation of the laser light.