An optical device including an acousto-optic modulator (AOM), a laser, an upstream optical fibre extending between the laser and the AOM, a downstream optical fibre located downstream of the AOM and a reflector connected to the fibre downstream of the AOM. The optical device including the upstream fibre is a polarisation-maintaining optical fibre, and/or the downstream fibre is arranged so that a transit time of the optical beam through said downstream fibre from the AOM to the reflecting means is nonzero and shorter than or equal to half an open duration of the AOM, and/or the AOM includes a crystal in which the entrance/exit faces are planar and are at a nonzero angle to each other, and/or at least one of the two entrance/exit faces is at a nonzero angle to a direction of propagation of the acoustic wave in the crystal.

A multi-wavelength laser system includes a first fiber laser having a first cavity mirror and a first output coupler, a first optical coupler configured to receive light from the first output coupler, a second fiber laser having a second cavity mirror and a second output coupler, and a second optical coupler configured to receive light from the second output coupler. The multi-wavelength laser system also includes a spectral beam combiner configured to receive first output light from the first optical coupler, receive second output light from the second optical coupler, combine the first output light and the second output light, and form a multi-wavelength output beam.

A laser amplifier for a green laser pulse includes at least one gain medium doped with praseodymium and at least one gallium nitride based diode laser for pumping the gain medium. A green seed laser pulse going through the gain medium becomes an amplified green laser pulse.

An active laser medium for emitting a light beam by laser effect includes an X—F2-doped crystal, wherein X is a chemical element from the alkaline-earth family and F is fluorine. The crystal is doped with trivalent ions including: a first category of optically active dopant ions, in which each dopant ion is an ion of a first rare earth; and a second category of optically inactive dopant ions, referred to as buffer ions, in which each dopant ion is an ion of a rare earth different from the first rare earth. The second category of dopant ions has at least ions of a second rare earth and ions of a third rare earth, different from one another. The invention provides an active laser medium that can be used to obtain both a desired emission spectrum shape and a high thermal conductivity.

An active laser medium for emitting a light beam by laser effect includes an X—F2-doped crystal, wherein X is a chemical element from the alkaline-earth family and F is fluorine. The crystal is doped with trivalent ions including: a first category of optically active dopant ions, in which each dopant ion is an ion of a first rare earth; and a second category of optically inactive dopant ions, referred to as buffer ions, in which each dopant ion is an ion of a rare earth different from the first rare earth. The second category of dopant ions has at least ions of a second rare earth and ions of a third rare earth, different from one another. The invention provides an active laser medium that can be used to obtain both a desired emission spectrum shape and a high thermal conductivity.

Disclosed is a laser radar device, which includes a signal light source that outputs a first signal light, a pump light source that outputs a pump light, a pump optical fiber that transfers the pump light, a first signal optical fiber that transfers the first signal light, a first amplifier that receives and amplifies the first signal light from the first signal optical fiber, a second signal optical fiber that receives and transfers a second signal light from the first amplifier, the second signal light being obtained by amplifying the first signal light, a second amplifier that receives and amplifies the second signal light from the second signal optical fiber, and an optical coupler connected to the first signal optical fiber, the second signal optical fiber, and the pump optical fiber, and that distributes the pump light to the first signal optical fiber and the second signal optical fiber.

A system includes a master oscillator configured to generate a first optical beam and a beam controller configured to modify the first optical beam. The system also includes a PWG amplifier configured to receive the modified first optical beam and generate a second optical beam having a higher power than the first optical beam. The second optical beam has a power of at least about ten kilowatts. The PWG amplifier includes a single laser gain medium configured to generate the second optical beam. The system further includes a feedback loop configured to control the master oscillator, PWG amplifier, and beam controller. The feedback loop includes a laser controller. The laser controller may be configured to process wavefront information or power in bucket information associated with the second optical beam to control an adaptive optic or perform a back-propagation algorithm to provide wavefront correction at an output of the PWG amplifier.

In an example, a tandem pumped fiber amplifier may include a seed laser, one or more diode pumps, and a single or plural active core fiber. The single or plural active core fiber may include a first section to operate as an oscillator and a second different section to operate as a power amplifier. The one or more diode pumps may be optically coupled to the first section of the single or plural active core fiber, and the seed laser may be optically coupled to the single active core or an innermost core of the plural active core fiber.

An optical amplification device includes a first Raman amplifier outputs a first excitation light to a transmission line in a same direction as a signal light, and a second Raman amplifier outputs a second excitation light to the transmission line in an opposite direction to the signal light. The first Raman amplifier includes a first detector detects a first power of a first transmitted light transmitted through a first optical filter. The second Raman amplifier includes a second detector detects second power of a second transmitted light transmitted through a second optical filter. The first Raman amplifier stops output of the first excitation light when the first power is higher than a threshold. The second Raman amplifier stops output of the second excitation light when the second power is reduced from power of the first excitation light transmitted through the second optical filter.

The invention discloses a method of amplifying an optical signal, in particular a data signal, transmitted from a first location (A) to a second location (B) via a first transmission link (10a), wherein said optical signal is amplified by means of a transmitter side remote optically pumped amplifiers (ROPA) (18) comprising a gain medium (24), wherein the gain medium (24) of said transmitter side ROPA (18) is pumped by means of transmitter side pump power (20) provided from said first location (A), characterized in that at least a part of said transmitter side pump power (20) is provided by means of light supplied from said first location (A) to said transmitter side ROPA (18) via a portion of a second transmission link (10b) provided for transmitting optical signals from said second location (B) to said first location (A).