Embodiments herein describe a path length adjuster for, e.g., adjusting the length of an optical cavity of a laser. In one embodiment, the path length adjuster includes a circulator element for ensuring unidirectional lasing. The path length adjuster may also include one or more focusing elements such as a focusing lens and/or a collimator which directs received laser light at a mirror. The mirror is mounted on an actuator that moves the mirror in a direction parallel with the propagation of the laser light, thereby increasing or reducing the length of the ring cavity.

A dual femtosecond optical frequency comb generation device is provided. The device includes a pump source, a wavelength division multiplexer, a piezoelectric ceramic, an erbium doped fiber, a single mode fiber, a first fiber collimating mirror, a second fiber collimating mirror, and spatial optical path elements, a first quarter-wave plate, a first half-wave plate, a polarization beam splitting prism, an optical isolator, a second half-wave plate and a second quarter-wave plate, and further including a grating pair, the grating pair being composed of a first grating and a second grating and being provided between the polarization beam splitting prism and the optical isolator. The device introduces the light distance difference by using the grating pair, so as to generate dual femtosecond optical frequency combs with a difference in repetition frequency, and the repetition frequency difference can be adjusted by the pitch of the grating pair.

A fiber laser system includes a fiber laser, a laser light detecting apparatus, and a control apparatus. The fiber laser outputs a laser light, including a noise-like pulse laser light, a mode-locked pulse laser light, or a continuous-wave laser light. The laser light detecting apparatus consists of a lens and a photodiode. The photodiode absorbs the laser light outputted from the fiber laser and generates an output signal in terms of a two-photon absorption effect. The control apparatus reads the output signal of the photodiode and automatically adjusts the fiber laser, according to a preset value, to obtain the noise-like pulse laser light or the mode-locked pulse laser light.

A device for interferometric distance measurement includes a multiple wavelength light source, which supplies a light beam having at least three different wavelengths and is configured as a fiber laser, which includes at least three different Bragg gratings, whose grating constants are matched to the wavelengths generated. In addition, an interferometer unit is provided, which splits up the light beam into a measuring light beam and a reference light beam. The measuring light beam propagates in a measuring arm, in the direction of a measuring reflector, and there, it is reflected back; the reference light beam propagates in a reference arm, in the direction of a stationary reference reflector, and there, it is reflected back. The measuring and reference light beams reflected back by the measuring and reference reflectors are superimposed in an interfering manner to form an interference light beam. The interference light beam is split up via a detection unit such that, in each instance, a plurality of phase-shifted, partial interference signals result per wavelength. With the aid of a signal processing unit, an absolute position information item regarding the measuring reflector is determined from the partial interference signals of different wavelengths.

A frequency swept laser source for TEFD-OCT imaging includes an integrated clock subsystem on the optical bench with the laser source. The clock subsystem generates frequency clock signals as the optical signal is tuned over the scan band. Preferably the laser source further includes a cavity extender in its optical cavity between a tunable filter and gain medium to increase an optical distance between the tunable filter and the gain medium in order to control the location of laser intensity pattern noise. The laser also includes a fiber stub that allows for control over the cavity length while also controlling birefringence in the cavity.

The present invention relates to an external cavity tunable laser and a cavity mode locking method thereof. In an embodiment, an external cavity tunable laser comprises a semiconductor amplifier having a partial reflective film provided on one end and an anti-reflective film provided on the other end, a cavity mirror provided at the anti-reflective end to define an external cavity therebetween, a large-range phasing assembly and a quick phasing assembly provided to adjust the optical length of the external cavity independently, an optical power detector provided to detect the optical power of the light output from the semiconductor amplifier, and a control unit in communication with the optical power detector, the large-range phasing assembly, and the quick phasing assembly.

A method of making a porous three-dimensional object. The method comprises: a) positioning a first layer of particles on a build plate; b) heating the first layer of particles sufficiently to fuse the particles together to form a first build layer having a first porosity; c) exposing the first build layer to a laser beam to form one or more pores, the exposed first build layer having a first modified porosity, the laser beam being emitted from an optical fiber; d) adjusting one or more beam characteristics of the laser beam prior to or during the exposing of the first build layer, the adjusting of the laser beam occurring prior to the laser beam being emitted from the optical fiber; e) positioning an additional layer of particles on the exposed first build layer; f) heating the additional layer of particles sufficiently to fuse the particles together to form a second build layer having a second porosity; g) exposing the second build layer to the laser beam to form one or more pores, the exposed second build layer having a second modified porosity, the laser beam being emitted from the optical fiber; h) adjusting one or more beam characteristics of the laser beam after fusing the particles to form the second build layer and prior to or during the exposing of the second build layer, the adjusting of the laser beam occurring prior to the laser beam being emitted from the optical fiber, and i) repeating e), f), optionally g) and optionally h) to form a three-dimensional object.

A frequency swept laser source for TEFD-OCT imaging includes an integrated clock subsystem on the optical bench with the laser source. The clock subsystem generates frequency clock signals as the optical signal is tuned over the scan band. Preferably the laser source further includes a cavity extender in its optical cavity between a tunable filter and gain medium to increase an optical distance between the tunable filter and the gain medium in order to control the location of laser intensity pattern noise. The laser also includes a fiber stub that allows for control over the cavity length while also controlling birefringence in the cavity.

An optical source comprises: a pump source operable to generate laser light at a first wavelength; a single mode optical fibre arranged to receive laser light at the first wavelength from the pump source, the optical fibre being fabricated from material having a Raman gain profile for stimulated Raman scattering of light at the first wavelength, and a Brillouin gain profile for stimulated Brillouin scattering of light at the second wavelength to a third wavelength longer than the second wavelength; and a superstructured fibre Bragg grating formed in the optical fibre, the grating comprising: a periodic refractive index profile along a core of the optical fibre, giving transmission of the first wavelength to allow received laser light at the first wavelength to enter the superstructured fibre Bragg grating, reflection of the second wavelength at a first level, and reflection of the third wavelength at a second level lower than the first level; and a phase shift at an intermediate location along a length of the grating; wherein the series of pulses at the third wavelength comprise a pulsed output of the optical source.

A fiber laser, null coupler acoustic Q-switch, fiber amplifier and feedback system is described for generation of high power laser pulses.