A compact possibly all free-space line-field swept source OCT system with a tunable cat's-eye laser.

The present disclosure discloses a hundred-kilowatts-level monolithic fiber laser based on auxiliary lasers and hybrid cladding pumping scheme. Multi-wavelength auxiliary lasers and a signal laser are simultaneously coupled into a core of a gain fiber, and the gain fiber provides gains for the auxiliary lasers and the signal laser under multi-wavelength cladding pumping. The multi-wavelength auxiliary lasers and the signal laser are sequentially amplified under the action of gain competition, and the amplification of signal laser is suppressed at a front segment of the gain fiber, while the signal laser is effectively amplified at a rear segment of the gain fiber after the multi-wavelength auxiliary lasers are reabsorbed; quantum defects generated are reduced, and uniformly distributed thermal loads will be achieved, and the bearing capacity of laser power is improved, thereby further achieving inhibition on the transverse mode instability effect.

A fiber laser amplifier system that employs a technique for reducing polarization modulation instability (PMI) in a delivery fiber. The system includes a fiber amplifier that amplifies a seed beam and provides the amplified seed beam to a weakly polarization maintaining (PM) delivery fiber that delivers the amplified beam to a certain location. The polarization of the seed beam is controlled so that it aligns with the slow axis of the delivery fiber such that nonlinear birefringence that occurs in the delivery fiber is added to the natural birefringence of the delivery fiber so as to suppress the PMI in the delivery fiber.

In one embodiment, a fiber-optic amplifier includes an optical gain fiber configured to amplify input light received from a seed laser. The optical gain fiber includes a first gain section configured to: receive the seed-laser input light and co-propagating pump light; and amplify the seed-laser input light as it propagates along the first gain section. The seed-laser input light and the co-propagating pump light propagate along the first gain section in a same direction. The optical gain fiber also includes a second gain section configured to: receive the amplified input light from the first gain section; receive counter-propagating pump light; and further amplify the amplified input light as it propagates along the second gain section. The amplified input light and the counter-propagating pump light propagate along the second gain section in opposite directions. The fiber-optic amplifier also includes a first pump laser diode and a second pump laser diode.

Disclosed is an all-fiber optical vortex laser based on resonance of orbital angular momentum modes. The all-fiber optical vortex laser has an annular cavity structure, and includes a narrow-linewidth pump laser, an optical amplifier, an orbital angular momentum mode generator, a first polarization controller, an optical fiber circulator, an optical fiber coupler, a second polarization controller and a vortex optical fiber. The orbital angular momentum mode generator (3) realizes directional conversion from a fundamental transverse mode in a single-mode optical fiber into an orbital angular momentum mode with a specific topological charge in a vortex optical fiber. The optical fiber coupler can realize directional coupling from an orbital angular momentum mode in one vortex optical fiber to an orbital angular momentum mode in another vortex optical fiber; the vortex optical fiber is an optical fiber supporting stable transmission of an orbital angular momentum mode.

A fiber amplifier has a first amplification stage and a second amplification stage. The first amplification stage comprises a first gain fiber that is configured to receive, at its input end, a signal light and a pump light. The first gain fiber uses a portion of the pump light to provide first-stage amplification to the signal light. The second amplification stage comprises a second gain fiber that is configured to receive, at its input end, the first-stage-amplified signal light and residual pump light. The second gain fiber uses the residual pump light to provide second-stage amplification of the first-stage-amplified signal light and to provide, at its output end, the second-stage amplified signal light. The first amplification stage may include a single-mode gain fiber, and the second amplification stage may include a higher-order-mode gain fiber, and the first amplification stage may be configured to provide single-mode amplification of a sub-threshold input to satisfy the low-ASE threshold of the second amplification stage.

A method for expanding a dynamic range of a light detection and ranging (LiDAR) system is provided. The method comprises transmitting, using a light source of the LiDAR system, a sequence of pulse signals consisting of two or more increasingly stronger pulse signals. The method further comprises receiving, using a light detector of the LiDAR system, one or more returned pulse signals corresponding to the transmitted sequence of pulse signals. The one or more returned pulse signals are above the noise level of the light detector. The method further comprises selecting a returned pulse signal within the dynamic range of the light detector, identifying a transmitted pulse signal of the transmitted sequence that corresponds to the selected returned pulse signal, and calculating a distance based on the selected returned signal and the identified transmitted signal.

An apparatus includes a plurality of input fibers including one or more signal fibers and one or more beam dump fibers, a signal combiner having an input end coupled to the plurality of input fibers so as to couple portions of one or more signal beams respectively propagating in one or more of the signal fibers to form a combiner beam, an output fiber coupled to an output end of the signal combiner so as to receive the combiner beam, and a beam dump coupled to at least one of the one or more beam dump fibers so as to receive a light beam propagating from the output fiber that is associated with the combiner beam.

Laser signal intensity is resonantly enhanced within a laser cavity to be greater than a pump intensity. This enables the suppression of excited-state absorption and is applicable to terbium-doped fiber lasers, lambda-type materials, or other materials used in lasers. In other embodiments, ESA is suppressed by de-populating the higher excited state using a resonant cavity.

In some implementations, an optical system includes a multicore input fiber comprising multiple cores that are each configured to support an independent singlemode laser; a delivery fiber comprising a single core configured to support multiple modes; and a signal combiner, coupled to the multicore input fiber and coupled to the delivery fiber. In some implementations, the signal combiner is configured to receive multiple independent singlemode laser inputs from the multicore input fiber and to combine the multiple independent singlemode laser inputs into a multimode output that is provided to the delivery fiber.