A measurement device includes: an optical gain unit for generating and amplifying light; a transmission optical band variation unit for selecting a specific optical frequency band from the light generated by the optical gain unit, and varying the selected specific optical frequency band to transmit light; a resonant optical frequency variation unit for performing a frequency variation so that multiple resonant optical frequency orders within the specific optical frequency band vary over a variation range narrower than intervals between the respective orders; resonance induction units forming an optical resonance unit which includes the optical gain unit, the transmission optical band variation unit, and the resonant optical frequency variation unit and causes selective oscillation of light having a specific resonant optical frequency within a specific transmission optical band; and a control signal unit for varying each of the transmission optical band variation unit and the resonant optical frequency variation unit.

A device includes: at least one laser element with light emitting points to output fundamental waves in a one-dimensional array; a wavelength converting element to carry out wavelength conversion of the incident fundamental waves, and to output wavelength converted light rays; and an output mirror to reflect the fundamental waves, and to transmit the wavelength converted light rays resulting from the wavelength conversion by the wavelength converting element. The wavelength converting element is disposed between the laser element and the output mirror, and the distance between the position of a waist of the fundamental waves output from the laser element and the output mirror is set in accordance with a Talbot condition under which the adjacent light emitting points cause phase synchronization with each other.

A wave guide may have an index profile including at least one maximum. The maximum or maxima of the index profile may correspond respectively to at least one maximum intensity of the outlet radiation with a mode of desired order. The wave guide may also have at least one doping ion configured to absorb the pump radiation. The doping ion or ions may have a concentration profile of doping ions including at least one maximum.

Disclosed is a terahertz laser device based on phonon vibration excitation, including a resonant cavity composed of a hollow waveguide made of a composite film and optical lenses at both ends of the waveguide, where M represents nano-metal particles. A zinc oxide mesomorphic microsphere is used herein as a source, symmetric stretching vibration of nanosheets on the zinc oxide microsphere is excited and induced by a laser and is transmitted through elastic and electric coupling among the nanosheets, and a terahertz wave with a frequency of 0.36 THz is radiated by means of phonon vibration; moreover, the zinc oxide mesomorphic microspheres and the nano-metal particles are mixed evenly to produce a strong local electric field a few nanometers nearby a surface of the metal particle by taking advantage of a surface-enhanced Raman effect of the nano-metal particles, a nanocantilever of the ZnO mesomorphic microsphere is greatly changed in polarizability with ample contact of the nano-metal particles and the ZnO mesomorphic microspheres, and thus the terahertz radiation power thereof is enhanced.

In one embodiment, a laser system includes a seed laser diode configured to produce a free-space seed-laser beam and a seed-laser focusing lens configured to focus the seed-laser beam. The laser system also includes a semiconductor optical amplifier (SOA) that includes a front facet, a back facet, and a waveguide extending from the front facet to the back facet. The SOA is configured to: receive, at the front facet, light from the focused seed-laser beam; amplify the received light as the received light propagates along the SOA waveguide from the front facet to the back facet; and emit, from the back facet, an amplified free-space beam that includes the amplified received light. The laser system further includes a mounting platform, where one or more of the seed laser diode, the seed-laser focusing lens, and the SOA are mechanically attached to the mounting platform.

In one embodiment, a laser system includes a seed laser diode configured to produce a free-space seed-laser beam and a seed-laser focusing lens configured to focus the seed-laser beam. The laser system also includes a semiconductor optical amplifier (SOA) that includes a front facet, a back facet, and a waveguide extending from the front facet to the back facet. The SOA is configured to: receive, at the front facet, light from the focused seed-laser beam; amplify the received light as the received light propagates along the SOA waveguide from the front facet to the back facet; and emit, from the back facet, an amplified free-space beam that includes the amplified received light. The laser system further includes a mounting platform, where one or more of the seed laser diode, the seed-laser focusing lens, and the SOA are mechanically attached to the mounting platform.

In one embodiment, a laser system includes a seed laser diode configured to produce a free-space seed-laser beam. The laser system also includes a pump laser diode configured to produce a free-space pump-laser beam. The laser system further includes an optical-beam combiner configured to combine the seed-laser and pump-laser beams into a combined free-space beam and a focusing lens configured to focus the combined beam. The laser system also includes an optical gain fiber that includes an input end configured to receive the focused beam. The laser system also includes a mounting platform, where one or more of the optical-beam combiner, the focusing lens, and the input end of the gain fiber are mechanically attached to the platform.

In one embodiment, an optical amplifier includes a first pump laser diode and a second pump laser diode. The first pump laser diode is configured to produce pump light that includes a first amount of optical power at a first wavelength, and the second pump laser diode is configured to produce pump light that includes a second amount of optical power at a second wavelength different from the first wavelength. The optical amplifier also includes an optical gain fiber configured to receive the pump light from the first and second pump laser diodes and provide optical gain for an optical signal propagating through the optical gain fiber. The optical amplifier further includes a controller configured to adjust the first amount of optical power produced by the first pump laser diode and the second amount of optical power produced by the second pump laser diode.

There are provided: a planar waveguide in which claddings (2) and (3) each having a smaller refractive index than a laser medium for absorbing pump light (5) are bonded to an upper surface (1a) and a lower surface (1b) of a core (1) which is formed from the laser medium; pump light generation sources (4a) and (4b) for emitting pump light (5) to side surfaces (1c) and (1d) of the core (1); and laser light high reflection films (6a) and (6b) formed on side surfaces (1e) and (1f) of the core (1). Each of side surfaces (2e) and (2f) of the cladding (2) corresponding to the side surfaces (1e) and (1f) of the core (1) has a ridge structure (20) in which a part thereof is recessed.

There are provided: a planar waveguide in which claddings (2) and (3) each having a smaller refractive index than a laser medium for absorbing pump light (5) are bonded to an upper surface (1a) and a lower surface (1b) of a core (1) which is formed from the laser medium; pump light generation sources (4a) and (4b) for emitting pump light (5) to side surfaces (1c) and (1d) of the core (1); and laser light high reflection films (6a) and (6b) formed on side surfaces (1e) and (1f) of the core (1). Each of side surfaces (2e) and (2f) of the cladding (2) corresponding to the side surfaces (1e) and (1f) of the core (1) has a ridge structure (20) in which a part thereof is recessed.