Abstract: Provided is a wavelength variable laser device wherein an SOA is simplified. The wavelength variable laser device includes: an optical filter formed on a PLC; an SOA that supplies light to the optical filter; a light reflecting section that returns the light transmitted through the optical filter to the SOA via the optical filter; optical waveguides which are formed on the PLC and connect the SOA, the optical filter, and the light reflecting section; a wavelength variable section that changes a wavelength of the light transmitting through the optical filter; and a phase variable section that changes a phase of the light propagated on the optical waveguides.

Abstract: According to one embodiment, a semiconductor light emitting device includes a first semiconductor layer and a laser resonator. The first semiconductor layer includes a first portion and a second portion juxtaposed with the first portion. The laser resonator is provided on the first portion and has a ring-shaped resonator structure circled along a major surface of the first semiconductor layer. The second portion guides light emitted from the laser resonator.

Abstract: A laser (12, 18) with a laser resonator (13), the laser resonator (13) having a non-linear optical loop mirror (1, 1?), NOLM, which is adapted to guide counter-propagating portions of laser pulses, and to bring the counter-propagating portions of laser pulses into interference with each other at an exit point (4) of the NOLM (1, 1?). The non-linear optical loop mirror (1, 1?) has a non-reciprocal optical element (7, 7?).

Abstract: A surface plasmon laser includes a metal layer, a gain medium layer provided on the metal layer and having a circular structure portion in which a whispering gallery mode is generated in which surface plasmon light generated due to surface plasmon resonance on an interface with the metal layer rotates along a circle, and a deformed portion formed to output part of laser light generated in the circular structure portion of the gain medium layer.

Abstract: The invention relates to a two-stage laser system well fit for semiconductor aligners, which is reduced in terms of spatial coherence while taking advantage of the high stability, high output efficiency and fine line width of the MOPO mode. The two-stage laser system for aligners comprises an oscillation-stage laser (50) and an amplification-stage laser (60). Oscillation laser light having divergence is used as the oscillation-stage laser (50), and the amplification-stage laser (60) comprises a Fabry-Perot etalon resonator made up of an input side mirror (1) and an output side mirror (2). The resonator is configured as a stable resonator.

Abstract: Devices for generating a laser beam are disclosed. The devices include a silicon micro ring having at least one silicon optical waveguide disposed at a distance from the micro ring. The radius and the cross-sectional dimension of the micro ring, the cross-sectional dimension of the waveguide, and the distance between the micro ring and the waveguide are determined such that one or more pairs of whispering gallery mode resonant frequencies of the micro ring are separated by an optical phonon frequency of silicon. Methods of manufacturing a lasing device including a silicon micro ring coupled with a silicon waveguide are also disclosed.

Abstract: A compact, lightweight, laser target designator uses a TIR bounce geometry to place an end-pumped gain element functionally in the center of the resonator path, thereby allowing the resonator path to be terminated by a pair of crossed Porro prisms, so that the designator produces a high quality beam that is insensitive to alignment and temperature, and is low in manufacturing cost. Some embodiments fold the Porro legs of the resonator path back toward the gain element for compactness. Embodiments use a single gain element as both an oscillator gain element with TIR and as an output amplifier gain element without TIR. Various embodiments use block optical elements in a planar layout on a standard support medium such as aluminum to facilitate automated manufacturing.

Abstract: Embodiments of the present invention provide improved systems and methods for providing an atomic sensor device. In one embodiment, the device comprises a sensor body, the sensor body enclosing an atomic sensor, wherein the sensor body contains a gas evacuation site located on the sensor body, the gas evacuation site configured to connect to a gas evacuation device. The device also comprises a getter container coupled to an opening in the sensor body, an opening in the getter container coupled to an opening in the sensor body, such that gas within the sensor body can freely enter the getter container. The device further comprises an evaporable getter enclosed within the getter container, the evaporable getter facing away from the sensor body.

Abstract: A ring laser includes a large-core rare-earth-doped fiber ring-connected with a free-space path having an electro-optic switch, output coupler, and intracavity band-pass filter to enforce lasing operation in narrow wavelength range. In some cavity-dumped modes, the laser is configured in a similar manner, except that an output coupler is omitted since the optical power is extracted from the laser cavity by the electro-optic switch itself. The same laser can be configured to operate in Q-switched and/or cavity-dumping modes as well as in hybrid modes (e.g., partial Q-switch, followed by cavity dumping, or even CW). In some embodiments, the laser can be used as, or inject laser light into, a regenerative solid-state amplifier, or a Raman laser, or can be also used to generate visible, ultra-violet, mid-infrared, and far-infrared (THz) radiation via nonlinear wavelength conversion processes. The various embodiments can use a power oscillator or seed-plus-amplifier MOPA configuration.

Abstract: A semiconductor laser includes a gain region; a distributed Bragg reflector (DBR) region including a diffraction grating; an end facet facing the DBR region with the gain region arranged therebetween; a first ring resonator including a first ring-like waveguide and a first optical coupler; a second ring resonator including a second ring-like waveguide and a second optical coupler; and an optical waveguide that is optically coupled to the end facet and extending in a predetermined optical-axis direction. The first and second ring resonators are optically coupled to the optical waveguide through the first and second optical couplers, respectively. Also, the DBR region, the gain region, and the end facet constitute a laser cavity. Further, the first ring resonator has a free spectral range different from a free spectral range of the second ring resonator.

Abstract: A system for generating multiple simultaneous laser wavelengths, said system comprising: a pulsed slave laser comprising a non-linear electro-optic crystal optically coupled to a lasing crystal in a ring cavity configuration, said non-linear electro-optic crystal configured to adjust an optical path length of said ring cavity in response to an applied voltage potential; an energy pump configured to initiate a pulse cycle in said pulsed slave laser in response to a trigger; a cavity control circuit configured to apply said voltage potential to said non-linear electro-optic crystal to generate a cavity resonance condition associated with said adjusted optical path length, said cavity control circuit further configured to provide said trigger to said energy pump in response to a detection of said cavity resonance condition; and one or more seed lasers configured to inject a single frequency laser beam into said pulsed slave laser.

Abstract: A pulse fiber laser device 1 has a Fabry-Perot type optical resonator, and is provided with an excitation light source 11, an optical coupling unit 12, an amplifying optical fiber 13, a saturable absorber 14, a gradient index lens 15, an optical output unit 16, a dispersion adjusting unit 17, a mirror 21 and a mirror 22. The saturable absorber 14 and the mirror 21, integrated into one body, constitute a saturable absorber mirror 23. The gradient index lens 15 converges the light output from an end face of an optical fiber 32 and outputs the light to the saturable absorber mirror 23, and inputs the light reflected from the saturable absorber mirror 23 into the end face of the optical fiber 32. Thus, there is provided a pulse fiber laser device that enables easy adjustment of the intensity of light incident on a saturable absorber and facilitates miniaturization.

Abstract: A high quality factor optical resonator structure includes a substrate, a center disc formed on the substrate, and a plurality of concentric grating rings surrounding the center disc. The concentric rings are spaced apart from the center disc and from one another by regions of lower index of refraction material with respect thereto, and wherein spacing between the grating rings and the center disc is non-periodic such that a magnitude of a displacement distance of a given grating ring with respect to a ?/4 Bragg reflector geometry is largest for a first of the grating rings immediately adjacent the center disk and decreases in a radially outward direction.

Abstract: A system (100) for generating a millimeter wave signals from heterodyning wavelengths from a multi-wavelength signal generated by a Brillouin-Erbium fiber laser (101). The Brillouin-Erbium fiber laser (101) includes a source laser (105) that transmits a seed signal. An optical directional coupler (110) has a first input that receives the seed signal from the source laser and a first output. An Erbium doped fiber amplifier (115) has an input connected to the first output of the optical directional coupler and an output. The Erbium doped fiber amplifier amplifies the seed signal. A four port circulator (120) has a first port that receives the seed signal from the Erbium doped fiber amplifier. A Brillouin gain medium (135) is connected to a second port and a third port of the circulator.

Abstract: Provided is a laser oscillation apparatus capable of stabilizing resonance even when finesse of an optical resonator is increased and generating stronger laser light than that of a traditional apparatus by accumulating laser light in the optical resonator.

Abstract: A hybrid CW MOPA includes an OPS-laser resonator delivering radiation in a plurality of longitudinal lasing-modes or wavelengths. The multiple longitudinal mode output is amplified in a fiber-amplifier. Amplified lasing-modes from the fiber-amplifier are frequency-converted by an optically nonlinear crystal in a ring-resonator having the same length as the laser resonator, such that the ring-resonator is resonant for all of the amplified lasing-modes.

Abstract: A component having a microring resonator and grating, coupled to a waveguide is described. By selection of the grating period, and other parameters such as the grating-waveguide coupling coefficient, an efficient filter may be designed and constructed. The component may be used in passive devices such as add-drop multiplexers or sensors, or in active devices such as lasers. Designs having essentially no response sidelobes, very narrow effective bandwidths, and fast filter roll-offs may permit compact devices to be produced, when compared with typical distributed sampled Bragg grating structures.

Abstract: In one embodiment, a semiconductor laser includes a semiconductor laminated body formed in a ring shape and first and second electrodes. The semiconductor laminated body includes an active layer, first and second cladding layers formed on both sides of the active layer, first and second contact layers formed on the first and second cladding layers, and first and second modified layers. The first and second modified layers are formed by selectively modifying the inner peripheral sidewalls and the outer peripheral sidewalls of the first and second cladding layers so as to have a refractive index lower than the refractive indexes of the first and second cladding layers. The first and second contact layers are electrically connected to the first and second electrodes.

Abstract: Techniques and devices that lock and stabilize a laser to an optical resonator via self-injection locking based on a reflection feedback. A whispering gallery mode optical resonator can be implemented to provide both the optical filtering and injection feedback based on the reflection feedback from feedback optics outside the optical resonator.

Abstract: The present invention provides a laser apparatus capable of improving a scan speed and achieving a scan rate equal to or more than 1 MHz, and an optical tomographic imaging apparatus using the laser apparatus as a light source. The laser apparatus includes a ring resonator, the ring resonator having a structure in which a first modulator, a normal dispersion region, a second modulator and an anomalous dispersion region are arranged in this order, and in this arrangement, a gain medium is included, and being configured so that modulation with respect to the second modulator can be caused to be phase modulation by periodically superimposing phase modulation on modulation with respect to the first modulator.

Abstract: A laser amplifier system is provided which comprises a resonator with optical resonator elements which determine a course of a resonator radiation field which propagates along an optical axis and at least one laser-active medium (LM). The resonator is designed as a split resonator and has a first resonator section which extends from a first virtual plane of separation and a second resonator section which extends from a second virtual plane of separation. The resonator sections are dimensioned optically such that the resonator radiation field has radiation field states corresponding to the same resonator modes in each of the virtual planes of separation. An amplifying unit optically independent of the resonator is arranged between the first and the second virtual planes of separation. The amplifying unit comprises the at least one laser-active medium and couples the radiation field states in a neutral manner with respect to the resonator modes.

Abstract: A laser system comprises a high-Q nonlinear optical resonator, a cavity comprising an amplifying element and a dispersive element, an optical delay line adapted to tune the length of the cavity, and a large pass-band filter adapted to tune the cavity's central oscillation wavelength, the nonlinear optical resonator being selected with a linewidth (LWR) comparable to the cavity free-spectral range (FSRC). There is provided a method for generating highly stable pulse streams, comprising providing a cavity comprising an amplifying element and a dispersive element; selecting a high-Q nonlinear optical resonator with a linewidth (LWR) comparable to the cavity free-spectral range (FSRC); tuning the length of the cavity; and tuning the cavity's central oscillation wavelength.

Abstract: A laser gyro for measuring the angular velocity or the angular position relative to a defined rotation axis includes: an optical ring cavity; a solid-state amplifying medium; and a non-reciprocal magneto-optic device; which are arranged so that four linearly polarized propagation modes can propagate within the cavity, the magneto-optic device introducing a frequency bias between the modes propagating in a first direction and the modes propagating in the opposite direction. In the device, the cavity also includes a stabilizer device for stabilizing the intensity of the four propagation modes at substantially equivalent levels, said device comprising at least one optical element made of a non-linear crystal of the frequency-doubling type.

Abstract: A laser apparatus may include a first laser light source configured to emit light with a first wavelength, a second laser light source including a titanium-sapphire laser device and a plurality of wavelength conversion elements and being configured to emit light with a second wavelength being one-fourth of a wavelength of light emitted from the titanium-sapphire laser device, and a wavelength conversion element configured in such a manner that the light with the first wavelength and the light with the second wavelength are incident thereon to emit light with a wavelength of about 193 nm corresponding to a sub frequency of the light with the first wavelength and the light with the second wavelength.

Abstract: An optical fiber laser including: a master oscillator; and a power amplifier, the power amplifier including: a plurality of excitation light sources; excitation ports each of which is connected to the excitation light sources and which an excitation light emitted from each of the excitation light source enters; a signal port which a laser beam emitted from the master oscillator enters; an optical coupler with an exit port that outputs the excitation lights from the excitation ports together with the laser beam from the signal port; and an optical fiber connected to the exit port, in which the optical fiber is a photonic bandgap fiber, and the optical fiber has a loss wavelength characteristic in that a photonic bandgap region is narrower than a gain wavelength band in a graph with an axis of abscissa representing a wavelength and an axis of ordinate representing a loss amount.

Abstract: The present invention discloses a manufacturing method of vertical cavity surface emitting laser. The method includes following steps: providing a substrate; forming an epitaxial layer stack including an aluminum-rich layer; forming an ion-doping mask including a ring-shaped opening; doping ions in the epitaxial layer stack through the ring-shaped opening and forming a ring-shaped ion-doped region over the aluminum-rich layer; forming an etching mask on the ion-doping mask for covering the ring-shaped opening of the ion-doping mask; etching the epitaxial layer stack through the etching mask and ion-doping mask for forming an island platform; oxidizing the aluminum-rich layer for forming a ring-shaped oxidized region. In addition, the present invention also discloses a vertical cavity surface emitting laser manufactured by the above mentioned method.

Abstract: An optical parametric oscillator including a nonlinear crystal pumped by a laser source and an optical resonator, including an optical interferometer, which determines a level of output coupling of the oscillator, allowing high stability, broad wavelength tuning, and output power level optimization.

Abstract: A composite optical waveguide 1 includes a first optical waveguide 9 comprising a silica-based core and a second optical waveguide 11 comprising an Si-based core. The second optical waveguide 11 is joined to the first optical waveguide 9. The length of the first optical waveguide 9 corresponds to a permissible propagation loss of the second optical waveguide 11. The second optical waveguide 11 includes a sharply curved portion 13 having a radius smaller than the minimum bend radius of the first optical waveguide 9.

Abstract: A light-emitting device having a ring optical resonator and capable of laser oscillation by a novel structure realized by working out the mechanism of light emission. The light-emitting device having a ring optical resonator fabricated on a base is characterized in that the optical resonator has a core made of a semiconductor and serving to propagate light and a clad formed on at least the base side of the core in the stack direction out of the base side and the opposite side of the core, at least the ring inner and outer peripheral surfaces of the core are covered with a transparent body having an index of refraction lower than that of the space or the clad, and a part of the ring inner and outer peripheral surfaces of the clad are covered with a transparent body having an index of refraction lower than that of the space or the clad.

Abstract: The invention relates to a fiber laser comprising a ring-shaped resonator (3). A first section of the resonator is formed by an optical fiber (7) while a second section of the resonator is formed by an optically pumped amplifier fiber (8). The fiber laser further comprises an injection point (4) for injecting light of a pump light source (1) into the resonator (3) as well as an extraction point (5) for extracting generated laser light from the resonator (3). The aim of the invention is to design a more developed fiber laser. The aim is achieved by providing the resonator (3) with at least one reflective optical component (12, 51) which reflects the laser light circulating in the resonator (3).

Abstract: A compact, light weight laser beam combiner includes a pair of concentric annular shells defining an annular cavity of an annular ring resonator having an annular solid laser gain medium disposed therein. The output ends of a plurality of low power and brightness fiber lasers are coupled into the cavity of the resonator such that fiber laser beams cause the gain medium in the resonator cavity to lase and produce an annular beam of laser light. Optical elements of the resonator are operable to feed a first portion of the laser light back through the resonator cavity to support regenerative lasing of the laser medium and to couple off a second portion of the laser light in the form of a circular beam of high power and high brightness laser light. A fluid may be circulated through the resonator cavity to cool the laser medium.

Abstract: Provided is a laser module. The laser module comprises: a substrate; an gain unit oscillating a laser light on the substrate; an external resonance reflecting unit total-reflecting the laser light at an external of the substrate adjacent to one side of the gain unit; and an inner resonance reflecting unit reflecting the laser light to the external resonance reflecting unit at the substrate between the modulating unit and gain unit and outputting the laser light to the modulating unit.

Abstract: An intense optical high field generator capable of generating an intensive optical high field includes an optical amplification medium that converts optical energy for a wide band or plural bands and performs optical energy conversion into oscillating light oscillated from an optical resonator. The generator also includes: a negative dispersion element that imparts negative dispersion to a pulse light, which is the oscillating light; a mode locking unit that mode locks the optical resonator; a positive dispersion element that imparts positive dispersion on the pulse light; an optical system; and a vacuum chamber that accommodates the negative dispersion element, the mode locking unit, and the positive dispersion element 4, such that an intensive optical high field generating point takes in the pulse light from the negative dispersion element or the positive dispersion element and is formed within the vacuum chamber.

Abstract: A controllable optical ring resonator, a photonic system and a method of controlling an optical ring resonator employ control electrodes periodically spaced apart along a closed loop optical path of an optical waveguide. The controllable optical ring resonator includes the optical waveguide and a plurality of the periodically spaced control electrodes. The photonic system includes an input optical waveguide segment and the controllable optical ring resonator adjacent and optically coupled to the segment. The method includes providing the plurality of periodically spaced control electrodes, providing an optical signal within the optical path, and addressing one or more of the control electrodes to interact with the optical signal within the optical path.

Abstract: An electromagnetically responsive element includes sets of arrangements of self-resonant bodies, such as atoms or quantum dots that form an effective dielectric constant, typically at or near a resonance.

Abstract: An electromagnetically responsive element includes sets of arrangements of self-resonant bodies, such as atoms or quantum dots that form an effective dielectric constant, typically at or near a resonance.

Abstract: A method of operating an all-fiber-based ultra short pulse laser system is provided. The steps includes providing an all-fiber-based ultra short pulse laser system having a pulse pump light source, a fiber saturable absorber, an assistant light source, at least a dispersion fiber, and a light coupling output; generating a broadband ASE via the pulse pump light source; making the all-fiber-based ultra short pulse laser system switch passive mode locking via the fiber saturable absorber; decreasing the restoring period of the fiber saturable absorber via the assistant light source; providing dispersion compensation via the dispersion fiber to output an ultra short pulse; and partially outputting a laser passing through the all-fiber-based ultra short pulse laser system via the light coupling output.

Abstract: An aspect of the disclosed subject matter includes a method of reducing the laser absorption of a beam reverser prism consisting of at least one of the following: increasing a first distance between a first incident point and a chamfered corner, wherein the first incident point is on a first reflective surface of the prism and the chamfered corner is formed between the first reflective surface and a second reflective surface of the prism, wherein the chamfered corner has a chamfered surface; increasing a second distance between a second incident point and the chamfered corner, wherein the second incident point is on the second reflective surface of the prism; and increasing a reflectivity of the chamfered surface of the chamfered corner of the prism. A method of determining a prime cut for an optical component is also disclosed. A laser including at least one prime cut optical component is also disclosed.

Abstract: A hollow-core optical-fiber filter is provided. The hollow-core optical-fiber filter includes a hollow-core optical fiber having a first end-face and an opposing second end-face. The first end-face and the second end-face set a fiber length. The hollow-core optical-fiber filter also includes a first reflective end-cap positioned at the first end-face and a second reflective end-cap positioned at the second end-face. When an optical beam from a laser is coupled into one of the first end-face or the second end-face, an optical output from the opposing end-face has a narrow linewidth and low frequency noise fluctuations.

Abstract: The invention concerns a gallery mode microdisc system for an electrically pumped optical source, the microdisc (1) being formed on one face of a substrate (2), the lower part of the microdisc being provided with an electrical contact referred to as the lower contact (4), the upper part of the microdisc being provided with an electrical contact referred to as the upper contact (6), the upper part of the microdisc being covered with a protective layer (3) of electrically insulating material, the central part (5) of the microdisc being electrically neutralized in order to prevent the passage of an electric current in said central part.

Abstract: The disclosure discloses a Fabry-Perot (F-P) cavity, which is a folded confocal cavity integrally formed by a monolithic optical element, the folded confocal cavity having three reflection surfaces, wherein a first reflection surface is a plane and at the same time serves as an input/output coupling surface, a second reflection surface is a plane, and a third surface is a spherical surface, curvature radius of which is equal to half of a round trip geometric length of light in the folded confocal cavity. The invention further discloses a laser based on the F-P cavity. The solution of the disclosure solves the problems in existing folded F-P cavity, such as unsatisfactory stability, sensitive to outside inferences, bulky and complicated construction.

Abstract: A split ring-resonator includes a substrate, an inner-trench or cavity formed into the substrate, the inner trench or cavity including a split, and an outer trench or cavity formed into the substrate around the inner trench or cavity, the outer trench or cavity including another split disposed at an opposite end of the split in the inner trench or cavity, wherein the inner trench or cavity and the outer trench or cavity are configured to receive an electrically conductive gas and/or plasma to form a split-ring resonator,

Abstract: Devices for generating a laser beam are disclosed. The devices include a silicon micro ring having at least one silicon optical waveguide disposed at a distance from the micro ring. The radius and the cross-sectional dimension of the micro ring, the cross-sectional dimension of the waveguide, and the distance between the micro ring and the waveguide are determined such that one or more pairs of whispering gallery mode resonant frequencies of the micro ring are separated by an optical phonon frequency of silicon. Methods of manufacturing a lasing device including a silicon micro ring coupled with a silicon waveguide are also disclosed.

Abstract: Embodiments are directed to systems and methods for adjusting a wavelength, bandwidth or both. Such systems and methods may be applicable to laser beams within a laser cavity or amplifier. For some embodiments, such systems and methods may be used to allow a user to set a desired wavelength and bandwidth of a short pulse laser system for operation at those parameters without further adjustment by the user.

Abstract: A wavelength-tunable directly modulated fiber ring laser is provided. Generally speaking, the wavelength-tunable directly modulated fiber ring laser employs an RSOA (reflective semiconductor optical amplifier) and an OTF (optical tunable filter) to construct a novel ring resonant cavity. Additionally, a signal generator can be further employed to transmit modulated signals to the RSOA, whereby generating light wave with the modulated signals, so as to provide tunable wave-length and direct modulation at the same time.

Abstract: A laser amplifier system is provided which comprises a resonator with optical resonator elements which determine a course of a resonator radiation field which propagates along an optical axis and at least one laser-active medium (LM). The resonator is designed as a split resonator and has a first resonator section which extends from a first virtual plane of separation and a second resonator section which extends from a second virtual plane of separation. The resonator sections are dimensioned optically such that the resonator radiation field has radiation field states corresponding to the same resonator modes in each of the virtual planes of separation. An amplifying unit optically independent of the resonator is arranged between the first and the second virtual planes of separation. The amplifying unit comprises the at least one laser-active medium and couples the radiation field states in a neutral manner with respect to the resonator modes.

Abstract: A linear-cavity all-fiber-based ultra short pulse laser system is provided. The all-fiber-based ultra short pulse laser system includes a pulse pump light source, a gain fiber, a first fiber signal pump combining unit, a broadband optical isolator, a fiber saturable absorber, an assistant light source, a second fiber signal pump combining unit, and a light coupling output. A broadband amplified spontaneous emission, emitted by the first fiber signal pump combining unit, which is connected to the pulse pump light source and the gain fiber, passes through the broadband optical isolator. The second fiber signal pump combining unit is connected to the assistant light source and the fiber saturable absorber. An ASE signal actively provides passive mode locking of the cavity, and the light coupling output partially outputs the laser. A dispersion fiber controls the temporal width.

Abstract: An optical apparatus includes a substrate comprising a layer of thermally insulating material disposed thereon; an optical resonator disposed on the layer of thermally insulating material; and a trench in the thermally insulating material disposed around at least a portion of the optical resonator. The optical resonator is substantially thermally isolated from the substrate.

Abstract: A laser-induced optical wiring apparatus is provided wherein optical wiring is realized by digital operations of a laser oscillator. The apparatus includes optical ring resonator formed of a loop-shaped optical waveguide on substrate. At least two optical gain sections are provided on the optical ring resonator. When each optical gain section is activated, a laser oscillator including the optical ring resonator and optical gain sections is enabled to oscillate. In this state, the gain of at least one of the optical gain sections is changed in accordance with an input signal, thereby changing the optical route gain of the optical ring resonator to change the oscillation state of the laser oscillator. A change in the laser oscillation state is detected by the optical gain section other than the at least one optical gain section, whereby an output signal is acquired.

Abstract: Provided is a laser apparatus including: a DFB fiber laser 40 including, as an amplitude medium, a rare earth doped silica optical fiber codoped with a high concentration of aluminum; an optical feedback path 50 formed by a ring-shaped optical fiber; and an optical coupler 70 a) feeding back a part of an output of the DFB fiber laser 40 to the DFB fiber laser 40 via the optical feedback path 50, and b) outputting, to outside, another part of the output of the DFB fiber laser 40, where the optical fiber forming the optical feedback path 50 is longer than a length at which a relaxation oscillation noise in the output to the outside becomes ?110 dB/Hz.