An optical pump may include a polarization element to separate pump light into a first component beam and a second component beam, wherein the polarization element is to separate the pump light such that the first component beam has a first polarization and the second component beam has a second polarization that is different from the first polarization. The optical pump may include a gain medium to absorb a portion of the first component beam and a portion of the second component beam, and transmit an unabsorbed portion of the first component beam and an unabsorbed portion of the second component beam. The optical pump may include one or more optical elements to at least partially isolate a pump source from the unabsorbed portion of the first component beam and the unabsorbed portion of the second component beam.

A method and a device is provided driving an optical laser diode (710, 711) during operation in an optical communication network, by determining a laser transfer function (741, 742) during operation of the laser diode (710, 711) and providing a control signal (750, 749) for driving the laser diode (710, 711) according to the laser transfer function (741, 742). Further, a method for driving a first and a second optical laser diode during operation in an optical communication network is provided. Furthermore, an optical amplifier and a communication system is suggested.

Self-isolated lasers are provided by using a chiral metasurface in combination with a spin-selective gain medium and symmetry-breaking (i.e., not linearly polarized) optical pumping. In preferred embodiments the chiral metasurface is resonant, thereby proving an integrated optical resonator to support lasing. The chiral metasurface can be the spin-selective gain medium, or it can be formed on a surface of the spin-selective gain medium, or it can be distinct from the spin-selective gain medium.

Provided are a light source device that is suitable for an optical amplifier including a plurality of optical amplification units and that can emit excitation light of optimal intensity to each of the optical amplification units, and an optical amplifier that uses this light source device. The light source device includes: first and second light sources that each emit excitation light; and a polarization beam combiner that includes first and second input ports and first and second output ports and that multiplexes/demultiplexes the pumping light emitted from the first and second light sources and inputted to the first and second input ports.

An all solid-state laser light source device comprises a diode-pump laser and the following devices sequentially arranged in an optical path direction of laser light: a coupling optical fiber, a coupling lens assembly, and a resonant cavity. An anisotropic laser crystal is provided in the resonant cavity. Absorption spectra of the anisotropic laser crystal comprise a π polarization absorption spectrum and a σ polarization absorption spectrum. Each of the π polarization absorption spectrum and the σ polarization absorption spectrum has a peak pump region and a left pump region and a right pump region arranged on either side of the peak pump region. Pump light outputted by diode-pump laser has a wavelength λ falling within the left pump region or the right pump region.

An all solid-state laser light source device comprises a diode-pump laser and the following devices sequentially arranged in an optical path direction of laser light: a coupling optical fiber, a coupling lens assembly, and a resonant cavity. An anisotropic laser crystal is provided in the resonant cavity. Absorption spectra of the anisotropic laser crystal comprise a polarization absorption spectrum and a polarization absorption spectrum. Each of the polarization absorption spectrum and the polarization absorption spectrum has a peak pump region and a left pump region and a right pump region arranged on either side of the peak pump region. Pump light outputted by diode-pump laser has a wavelength falling within the left pump region or the right pump region.

An optical pump may include a polarization element to separate pump light into a first component beam and a second component beam, wherein the polarization element is to separate the pump light such that the first component beam has a first polarization and the second component beam has a second polarization that is different from the first polarization. The optical pump may include a gain medium to absorb a portion of the first component beam and a portion of the second component beam, and transmit an unabsorbed portion of the first component beam and an unabsorbed portion of the second component beam. The optical pump may include one or more optical elements to at least partially isolate a pump source from the unabsorbed portion of the first component beam and the unabsorbed portion of the second component beam.

[Problem] An excitation light output is improved without generating heat and lowering an operational life. [Solution] A laser element includes: a laminated semiconductor layer that includes a first reflection layer used for light of a first wavelength and an active layer that performs surface light emission at the first wavelength; a second reflection layer that is disposed closer to a light emission surface side than the laminated semiconductor layer, and is used for the light of the first wavelength; and a polarization splitting element that individually resonates and multiplexes each of orthogonal polarized beams included in light emitted from the laminated semiconductor layer between the first reflection layer and the second reflection layer.

Self-isolated lasers are provided by using a chiral metasurface in combination with a spin-selective gain medium and symmetry-breaking (i.e., not linearly polarized) optical pumping. In preferred embodiments the chiral metasurface is resonant, thereby proving an integrated optical resonator to support lasing. The chiral metasurface can be the spin-selective gain medium, or it can be formed on a surface of the spin-selective gain medium, or it can be distinct from the spin-selective gain medium.