Methods, systems, and devices are disclosed for divided-pulse lasers. In one aspect, a pulsed laser is provided to include a laser cavity including an optical amplifier and a plurality of optical dividing elements and configured to direct a laser pulse of linearly polarized light into the plurality of optical dividing elements to divide the light of the laser pulse into a sequence of divided pulses each having a pulse energy being a portion of the energy of the laser pulse before entry of the optical dividing elements, to subsequently direct the divided pulses into the optical amplifier to produce amplified divided pulses. The laser cavity is configured to direct the amplified divided pulses back into the plurality of optical dividing elements for a second time in an opposite direction to recombine the amplified divided pulses into a single laser pulse with greater pulse energy as an output pulse of the laser cavity.

Provided is a tunable laser source including a plurality of optical waveguides, at least three optical resonators provided between the plurality of optical waveguides and optically coupled to the plurality of optical waveguides, the at least three optical resonators having different lengths, and at least one optical amplifier provided on at least one of the plurality of optical waveguides, wherein a ratio of a first length of a first optical resonator of the at least three optical resonators to a second length of a second optical resonator of the at least three optical resonators is not an integer.

An optical source is described. This optical source includes a set of semiconductor optical amplifiers, with a semiconductor other than silicon, which provides an optical gain medium. In addition, a photonic chip, optically coupled to the set of semiconductor optical amplifiers, includes optical paths. Each of the optical paths includes an optical waveguide and a distributed-Bragg-reflector (DBR) ring resonator. The DBR ring resonator at least partially reflects a given tunable wavelength in an optical signal provided by a given semiconductor optical amplifier. Moreover, the DBR ring resonator includes a different number of grating periods than DBR ring resonators in the remaining optical paths, and the DBR ring resonators in the optical paths have a common radius.

An optical source is described. This optical source includes a set of semiconductor optical amplifiers, with a semiconductor other than silicon, which provides an optical gain medium. In addition, a photonic chip, optically coupled to the set of semiconductor optical amplifiers, includes optical paths. Each of the optical paths includes an optical waveguide and a distributed-Bragg-reflector (DBR) ring resonator. The DBR ring resonator at least partially reflects a given tunable wavelength in an optical signal provided by a given semiconductor optical amplifier. Moreover, the DBR ring resonator includes a different number of grating periods than DBR ring resonators in the remaining optical paths, and the DBR ring resonators in the optical paths have a common radius.

An unidirectional short-wave infrared fiber laser, comprising a theta cavity, with a gain unit based on rare-earth cations-doped fiber, the theta cavity having a ring cavity with two additional 2 input ports2 output ports directional couplers DC1 and DC2 inserted therein, one port of the directional coupler DC1 connected to another port of the directional coupler DC2, forming an S-shaped feedback; a band-pass filter to select at a laser wavelength by filtering through transmission inside the theta cavity, the band-pass filter is one of the list comprising a grating-based filter, a Fabry-Perot etalon, and a phase shifted fiber-Bragg grating; and a reflective fiber Bragg grating (FBG) to select the laser wavelength by filtering through reflection inside the theta cavity, the Bragg grating is a notch filter, and the fiber Bragg grating (FBG) is attached to an unused port of the directional coupler DC1 or DC2.

Example embodiments relate to lasers that include loop resonators. One example laser includes a loop resonator forming a closed loop light path. The loop resonator includes an optical gain medium configured to lase. The loop resonator is configured to, during lasing, present a pair of modes: a mode of light propagating in a clockwise direction in the closed loop light path of the loop resonator (termed CW mode) and a mode of light propagating in a counter-clockwise direction in the closed loop light path of the loop resonator (termed CCW mode). The laser also includes a first light output configured to output laser light from the laser. Additionally, the laser includes an optical power modulating unit. The optical power modulation unit is configured to modulate an optical power of the CW mode of the loop resonator and an optical power of the CCW mode of the loop resonator.

A system and method for stabilizing and combining multiple emitted beams into a single system using both WBC and WDM techniques.

A system based on recombination by superposition using a diffractive optical element DOE to combine the beams is provided. An optical diffractive assembly is placed upstream of a diffractive optical element to make it possible, via an appropriate imaging system, to optimize the combining efficiency in the ultra-short pulse regime.

A desired N.sup.th-order Stokes output and zeroth-order Stokes pump input are seeded into a rare-earth doped amplifier where the power of the zeroth-order Stokes signal is amplified prior to both signals entering a Raman amplifier comprised of N1 Raman resonators, each uniquely tuned to one of the N1 Stokes orders, in various configurations to include one or more nested and/or in-series Raman resonators. The zeroth-order Stokes signal is converted to the N.sup.th1-order Stokes wavelength in steps and the power level of the N.sup.th-order Stokes wavelength is amplified as the two signals propagate through the Raman resonators. Each Raman resonator includes a photosensitive Raman fiber located between a pair of Bragg gratings. The linewidths of the Stokes orders can be controlled by offsetting the reflectivity bandwidths of each pair of Bragg gratings respectively located in the Raman resonators.

A multimode (MM) fiber oscillator is configured with MM active fiber doped with light emitters, a pair of MM passive fibers spliced to respective opposite ends of the MM active fiber, and a plurality of MM fiber Bragg gratings (FBG) written in respective cores of the MM passive fibers to provide a resonant cavity. The passive and active fibers are configured with respective cores which are dimensioned with respective diameters matching one another and substantially identical numerical apertures.