An optical semiconductor device outputting a predetermined wavelength of laser light includes a quantum well active layer positioned between a p-type cladding layer and an n-type cladding layer in thickness direction. The optical semiconductor device includes a separate confinement heterostructure layer positioned between the quantum well active layer and the n-type cladding layer. The optical semiconductor device further includes an electric-field-distribution-control layer positioned between the separate confinement heterostructure layer and the n-type cladding layer and configured by at least two semiconductor layers having band gap energy greater than band gap energy of a barrier layer constituting the quantum well active layer. The optical semiconductor device is applied to a ridge-stripe type laser.

A Distributed Feedback Laser (DFB) mounted on a Silicon Photonic Integrated Circuit (Si PIC), the DFB having a longitudinal length which extends from a first end of the DFB laser to a second end of the DFB laser, the DFB laser comprising: an epi stack, the epi stack comprising: one or more active material layers; a layer comprising a partial grating, the partial grating extending from the second end of the DFB laser, only partially along the longitudinal length of the DFB laser such that it does not extend to the first end of the DFB laser; a highly reflective medium located at the first end of the DFB laser; and a back facet located at the second end of the DFB laser.

A system includes multiple first thulium-doped fiber lasers each configured to generate pumplight. The system also includes a second thulium-doped fiber laser configured to receive the pumplight from the first thulium-doped fiber lasers and a seed signal. The second thulium-doped fiber laser is also configured to amplify the seed signal using the pumplight. The first thulium-doped fiber lasers are configured to forward-pump the second thulium-doped fiber laser. The second thulium-doped fiber laser includes a fiber gain medium, where the fiber gain medium includes a core doped with thulium and a cladding. The fiber gain medium is longitudinally up-tapered such that a diameter of the core and a diameter of the cladding increase along at least a portion of a length of the fiber gain medium.

There is described a fiber laser system generally having a pump laser generating a pump laser beam; and a length of optical fiber optically coupled to the pump laser, the length of optical fiber having: a laser cavity having a cavity path, a first fiber Bragg grating having a first reflectivity profile, a second filter having a second filter profile, and an optical gain region between the first fiber Bragg grating and the second filter along the cavity path, the first reflectivity profile being spectrally detuned from the second filter profile, the first fiber Bragg grating having a first refractive index profile comprising a full width at half maximum bandwidth of at least 0.2 nm and a Gaussian-like apodization, wherein, upon pumping of the optical gain region with the pump laser beam and mode locking of the laser cavity, optical pulses are circulated along the cavity path; and an output.

A high-precision repetition rate locking apparatus for an ultra-fast laser pulse includes: an electronic controlling component comprising: a standard clock, configured to provide a high-precision frequency standard; a pulse generator (PG), configured to provide an electrical pulse signal with adjustable repetition rate, pulse width and voltage magnitude; and a signal generator (SG), connected to the standard clock and the PG, and configured to provide a stable frequency signal for the PG, a phase-shift adjusting component, connected to the electronic controlling component and configured to implement phase modulation through electrically induced refractive index change; a resonant cavity component, comprising a phase shifter, a doped fiber, a laser diode, a wavelength division multiplexer and a reflector, and configured to generate a mode-locked pulse; and a detection system, configured to measure a repetition rate of an output pulse.

A fluorescence guide plate includes first and second surfaces, an edge surface connecting a periphery of the first surface with a periphery of the second surface, and a dichroic mirror laminated on the first surface. Fluorescent material is dispersed at least one of inside a space defined by the first surface, the second surface, and the edge surface, on the first surface, or on the second surface. The fluorescence guide plate has a plate-shaped structure made of a material with a higher refractive index than an outside. The fluorescence guide plate is configured such that, when irradiation light enters from the first surface, the fluorescence emitted from the fluorescent material exits from the edge surface. A reflection wavelength band of a normal incident beam reflected by the dichroic mirror lies in a range of wavelengths longer than a peak wavelength of a fluorescence wavelength band of the fluorescent material.

Systems and methods for temporal amplitude modulation of an optical beam. An exemplary system may include a birefringent fiber positioned between two polarizers, or between a polarized input light source and an output polarizer. Light may enter the birefringent fiber as linearly polarized. Depending on birefringence and orientation of the birefringent fiber, the polarization state changes as the light propagates through the birefringent fiber. This changed polarization state then enters the output polarizer, for which transmission is a function of the polarization state and the relative orientation of the polarization axis. The polarization state emerging from the birefringent fiber may be changed by modulating the fiber birefringence, for example through application of an external stress. Net transmittance of the system may be varied according to a magnitude of an external force (e.g., pressure) to some or all of the birefringent fiber.

An optical fiber amplifier is formed to include a grating structure inscribed within the rare earth-doped gain fiber itself, providing distributed wavelength-dependent filtering (attenuation) and minimizing the need for any type of gain-flattening filter to be used at the output of the amplifier. The grating structure may be of any suitable arrangement that provides the desired loss spectrum, for example, similar to the profile of a prior art discrete GFF. Various types of grating structures that may be used to provide distributed wavelength-dependent filtering along the gain include, but are not limited to, tilted gratings, weak Bragg gratings, long-period grating (LPG), and any suitable combination of these grating structures.

An objective is to provide an optical amplifier having a core excitation configuration that improves amplification efficiency. An optical amplifier according to the present invention includes an excitation light conversion fiber 11 that absorbs first excitation light L1 propagating in a cladding and having a first wavelength and emits, into a core, spontaneous emission light having a second wavelength, an oscillator 12 for causing the spontaneous emission light to be reflected on two reflectors 15 to reciprocate the light within the core of the excitation light conversion fiber 11 and laser-oscillating second excitation light L2 having the second wavelength, and an amplification fiber 13 that is connected to the excitation light conversion fiber 11 and amplifies signal light with the second excitation light L2 supplied from the excitation light conversion fiber 11 to the core.

An object is to provide an optical amplifier with a cladding pumped configuration that improves amplification efficiency. The optical amplifier according to the present invention includes a pump light conversion fiber 11 that converts first pump light L1 with a first wavelength propagating in a cladding into second pump light L2 with a second wavelength, an amplification fiber 13 that is connected to the pump light conversion fiber 11 and optically amplifies signal light Ls with the second pump light L2 supplied to the cladding from the pump light conversion fiber 11, and an oscillator 12 that causes the second pump light L2 to be reflected on two reflectors 15 and to reciprocate within the claddings of the pump light conversion fiber 11 and the amplification fiber 13 to cause laser oscillation of the second pump light L2.