An extra cavity harmonic generator system may produce a round, non-astigmatic third harmonic output beam from a nominally round, non-astigmatic, diffraction limited input fundamental beam. The system may include a second harmonic generation crystal. An input fundamental beam size is expanded in a non-walkoff direction for the SHG crystal at the SHG crystal input face. A higher harmonic generation crystal has an output face oriented at an oblique angle of incidence in a non-walkoff direction for the HHG crystal such that an output higher harmonic beam size is contracted in this direction. Expansion of the input fundamental beam at the SHG crystal input face exceeds reduction of third harmonic beam at the HHG crystal output face.

Disclosed is a method of Controlling a gain of an optical amplifier comprising a gain medium and at least one pumping device. The method comprises the following steps: determining or predicting a change of input signal power to the amplifier, changing the pump power from an initial pump power level to a new pump power level at a first time instant, the initial pump power level being the pump power level applied to the amplifier prior to the change in input signal power, setting the pump power to a second pump power level at a second time instant, wherein the pump power level is varied in an oscillatory manner for at least one period of time starting at a third time instant and ending at a fourth time instant, wherein said third time instant is identical with or later than said first time instant and said fourth time instant is identical with or earlier than said second time instant.

A broad line red light generator is configured with a single mode (SM) pulsed ytterbium (“Yb”) fiber laser pump source outputting pump light in a fundamental mode (“FM”) at a pump wavelength which is selected from a 1030-1120 nm wavelength range. The disclosed generator further includes a SM fiber Raman converter spliced to an output of the Yb fiber laser pump source. The Raman converter induces an “n” order frequency Stokes shift of the pump light to output the pump light at a Raman-shifted wavelength within 1220 and 1300 nm wavelength range with a broad spectral line of at least 10 nm. The disclosed light generator further has a single pass second harmonic generator (“SHG”) with a lithium triborate (“LBO”) nonlinear optical crystal having a spectral acceptance linewidth which is sufficient to cover the broad spectral line of the pump light. The SHG generates a SM pulsed broad-line red light with a broad spectral line of at least 4 nm.

A multi-stage optical amplifier has an input port for receiving an optical signal and a relatively short erbium doped optical fiber is coupled to the input port. Complex costly pump feedback is not required as a constant non-varying saturation pump is configured to provide non varying output power pump light of a predetermined wavelength suitable for excitation and full saturation of the erbium ions such that a full population inversion occurs. The length of the short erbium doped fiber and rare earth doping concentration of the erbium doped fiber is such that when pumped by said pump provides amplification of the optical signal of less than 15 dB. Locating a gain flattening filter after the short erbium doped optical fiber provides a relatively flat amplified output signal. Multi-stages of similar short erbium doped fibers pumped and saturated by the same pump signal economically provide increased amplification of the signal and filters after each state flatten the gain.

The present invention discloses a high-peak-power single-frequency narrow-linewidth nanosecond fiber laser based on a triangular pulse, wherein the laser includes: pulsed laser generated by the laser seed injecting into a first power pre-amplifier through a first isolator, and then injecting into a second pre-amplifier and then injecting into a power amplifier; wherein triangle-shaped pulsed laser with fast rising edge is obtained by using electro-optic and acousto-optic modulator to modulate continuous wave single-frequency laser or a single-frequency semiconductor laser directly modulated by radio frequency signal; single-frequency triangle-shaped pulsed laser is employed as the laser source according to the characteristics of narrow intrinsic linewidth and suppression of linewidth broadening caused by SPM, and the power of pulsed laser is amplified through the MOPA system.

The present disclosure relates to a fiber encapsulation mechanism for energy dissipation in a fiber amplifying system. One example embodiment includes an optical fiber amplifier. The optical fiber amplifier includes an optical fiber that includes a gain medium, as well as a polymer layer that at least partially surrounds the optical fiber. The polymer layer is optically transparent. In addition, the optical fiber amplifier includes a pump source. Optical pumping by the pump source amplifies optical signals in the optical fiber and generates excess heat and excess photons. The optical fiber amplifier additionally includes a heatsink layer disposed adjacent to the polymer layer. The heatsink layer conducts the excess heat away from the optical fiber. Further, the optical fiber amplifier includes an optically transparent layer disposed adjacent to the polymer layer. The optically transparent layer transmits the excess photons away from the optical fiber.

Bismuth (Bi) doped optical fibers (BiDF) and Bi-doped fiber amplifiers (BiDFA) are shown and described. The BiDF comprises a gain band and an auxiliary band. The gain band has a first center wavelength (λ1) and a first six decibel (6 dB) gain bandwidth. The auxiliary band has a second center wavelength (λ2), with λ2>λ1. The system further comprises a signal source and a pump source that are optically coupled to the BiDF. The signal source provides an optical signal at λ1, while the pump source provides pump light at a pump wavelength (λ3).

A laser device includes element circuits, a front optical system, and a reflective optical system. The front optical system forms a plurality of light beams by collimating a plurality of phase modulated light signals input from the element circuits, and generate a plurality of partially reflected light signals by partially reflecting the plurality of phase modulated light signals. The reflective optical system multiplexes the input local oscillation light with the plurality of partially reflected light signals by reflecting the local oscillation light in a direction of the front optical system. The element circuits can convert each of a plurality of interference light signals generated by multiplexing of the plurality of partially reflected light signals and the local oscillation light into a plurality of electric signals, and can detect a phase error between the plurality of electric signals and a reference signal.

A dual output laser diode may include first and second end facets and an active section. The first and second end facets have low reflectivity. The active section is positioned between the first end facet and the second end facet. The active section is configured to generate light that propagates toward each of the first and second end facets. The first end facet is configured to transmit a majority of the light that reaches the first end facet through the first end facet. The second end facet is configured to transmit a majority of the light that reaches the second end facet through the second end facet.

A dual output laser diode may include first and second end facets and an active section. The first and second end facets have low reflectivity. The active section is positioned between the first end facet and the second end facet. The active section is configured to generate light that propagates toward each of the first and second end facets. The first end facet is configured to transmit a majority of the light that reaches the first end facet through the first end facet. The second end facet is configured to transmit a majority of the light that reaches the second end facet through the second end facet.