A swept light source of the present invention keeps a coherence length of an output beam long over an entire sweep wavelength range. A gain of a gain medium is changed with time in response to a wavelength sweep and the coherence length is kept maximum. The gain of the gain medium is kept close to a lasing threshold and an unsaturated gain range of the gain medium is narrowed over the entire sweep wavelength range. An SOA current waveform data acquiring method of driving while keeping the coherence length long, a novel coherence length measuring method, and an optical deflector suitable for the swept light source are also disclosed.

In various embodiments, laser systems feature beam emitters thermally coupled to heat sinks comprising, consisting essentially of, or consisting of a metal-matrix composite of a thermally conductive metal and a refractory metal. At least a portion of the surface of the heat sink is treated to form a depleted region, and a diamond coating is deposited within and/or over the depleted region. The depleted region is substantially free of the thermally conductive metal or contains the thermally conductive metal at a concentration less than that of the body of the heat sink.

In various embodiments, a laser emitter such as a diode bar is cooled during operation via jets of cooling fluid formed by ports in a cooler on which the laser emitter is positioned. The jets strike an impingement surface of the cooler that is thermally coupled to the laser emitter but prevents direct contact between the cooling fluid and the laser emitter itself.

Methods for wavelength determination of widely tunable lasers and systems thereof may be implemented with solid-state laser based photonic systems based on photonic integrated circuit technology as well as discrete table top systems such as widely-tunable external cavity lasers and systems. The methods allow integrated wavelength control enabling immediate system wavelength calibration without the need for external wavelength monitoring instruments. Wavelength determination is achieved using a monolithic solid-state based optical cavity with a well-defined transmission or reflection function acting as a wavelength etalon. The solid-state etalon may be used with a wavelength shift tracking component, e.g., a non-balanced interferometer, to calibrate the entire laser emission tuning curve within one wavelength sweep. The method is particularly useful for integrated photonic systems based on Vernier-filter mechanism where the starting wavelength is not known a-priori, or for compact widely tunable external cavity lasers eliminating the need for calibration of wavelength via external instruments.

A device comprises three elements. The first element, comprising an optical gain structure and a laser cavity mirror structure, couples light to the second element, comprising a phase tuner. The second element couples phase tuned light to the third element. The third element, comprising an optical resonator with first and second coupler/splitter structures, provides a primary optical output from the second coupler/splitter structure. Light coupled into the optical resonator through the first coupler/splitter structure and then coupled out of the optical resonator though the first coupler/splitter structure is injected back into the optical gain structure through the second element. Light coupled out of the optical resonator through the second coupler/splitter structure is provided as the primary optical output. Characteristic of the coupler/splitter structures and the optical resonator are selected such that the light injected back into the optical gain structure reduces linewidth, and noise in primary optical output is suppressed.

In various embodiments, a wavelength beam combining laser system includes a fast-axis collimation lens that is rotated with respect to a plurality of emitters in order to converge the emitted beams onto a dispersive element and/or reduce the size of the multi-wavelength output beam of the system.

Provided is a laser oscillation device including; a plurality of semiconductor laser diodes (1a to 1e); optical component (5) that directs a plurality of laser beams emitted from the plurality of semiconductor laser diodes in a specific direction to generate a superimposed laser beam including the plurality of laser beams and propagating in the specific direction; and optical switching element (130) that receives the superimposed laser beam from optical component (5). The superimposed laser beam has a plurality of wavelengths.

The laser device includes a first mirror and a second mirror forming a resonator, a gain medium disposed between the first mirror and the second mirror and having a light emitting surface, an antireflection film provided on the light emitting surface of the gain medium, at least one optical element disposed between the gain medium and the second mirror, and a diffraction grating disposed between the optical element and the second mirror. The gain medium is a semiconductor layered body including an active layer and having a varying gain distribution in at least a first direction within the light emitting surface, and includes no waveguide.

There is provided a tunable external-cavity laser and a tunable laser source based on such tunable external-cavity laser. The tunable external-cavity laser comprises: two reflective surfaces to form a laser cavity therebetween; an active waveguide for amplifying laser light propagating in the laser cavity; a tunable wavelength-selective filter within the laser cavity for selecting the emission wavelength of the tunable external-cavity laser with in a tuning range; and a collimating lens system for collimating the optical beam out of the active waveguide for propagation in the laser cavity. The collimating lens system comprises an imaging lens and a collimating lens for collimating the optical beam. The imaging lens induces a positive chromatism within the tuning range and the collimating lens comprises a complex lens inducing a negative chromatism within the tuning range so as to at least partially compensate for the positive chromatism induced by the imaging lens.

The semiconductor laser device includes: semiconductor laser elements; lenses; a deflection element; a wavelength dispersion element that wavelength-couples emitted light beams to form coupled light; and a partial reflection mirror. The lenses include a first lens that reduces a divergence angle of the emitted light beams in a first axis direction, and a second lens that is disposed between the first lens and the wavelength dispersion element and reduces the divergence angle of the laser beams in a second axis direction. The deflection element has planes each corresponding to the emitted light beams, at least one plane among the planes is inclined with respect to an optical axis of a corresponding one of the emitted light beams, which corresponds to each of the at least one plane, and the emitted light beams overlap one another on the wavelength dispersion element.