Abstract: An optical channel monitor (OCM) may include a modulator to provide a modulation signal and a local oscillator (LO) to provide a modulated LO signal. The modulated LO signal may be created by modulating an LO signal based on the modulation signal. The OCM may include a mixer to generate a pair of mixed optical signals. The pair of mixed optical signals may be generated based on mixing the modulated LO signal and an input optical signal. The OCM may include an optical detector to provide, based on the pair of mixed optical signals, a first electrical signal corresponding to a coherent mixture of the input optical signal and the modulated LO signal. The OCM may include a synchronous demodulator to provide, based on the first electrical signal and the modulation signal, a second electrical signal representative of the optical power spectrum of the input optical signal.

Abstract: The present disclosure provides a unique digitally integrated, self-trained pre-distortion curve generation method and apparatus for semiconductor lasers (SCLs) to generate linearly swept optical signals that are applicable to a wide range of sweep velocities and semiconductor laser types. The method requires no prior knowledge of the frequency response of the laser and is highly accurate.

Abstract: A light source unit for thermally-assisted magnetic head includes a substrate member having a bonding surface, multiple layers formed on the bonding surface and comprising a base layer, a connection pad layer, an insulation layer and a bonding layer; a light source assembly attached on the bonding layer of the substrate member and having a laser diode embedded therein and connected to the connection pad layer on the bonding surface, so as to form a laser diode circuit; and a heater buried in the insulation layer and connected to the connection pad layer, so as to form a heater circuit. The light source unit can maintain stable heat power for facilitating performance of the thermally-assisted magnetic head, and further reduce the sizes of the light source unit and substrate member.

Abstract: A light source device according to the present disclosure that is provided with a semiconductor laser unit configured to emit excitation light of a prescribed wavelength, a wavelength conversion unit configured to amplify the excitation light by causing the excitation light to resonate and generate output light of a different wavelength from the excitation light using a prescribed non-linear crystal, the wavelength conversion unit including a first optical path for amplifying the excitation light, and a second optical path for generating the output light, a first servo mechanism configured to control an optical path length of the first optical path, and a second servo mechanism configured to control an optical path length of the second optical path.

Abstract: A laser device includes an excitation light source, a resonator which receives excitation light from the excitation light source and generates laser light, an absorption cell to which the laser light is emitted, a light converter which converts the laser light passing through the absorption cell to a light output signal, a third order differential lock-in amplifier which generates a third order differential signal of the light output signal, and a controller. When a predetermined waveform of the third order differential signal is detected, the controller includes a return controller that determines a return direction of a resonator length based on the predetermined waveform and a resonator length controller that changes the resonator length to the return direction.

Abstract: A laser system includes a laser source operable to provide a laser beam; a laser amplifier having an input port and an output port and operable to amplify the laser beam, the laser beam travelling along a main beam path through the laser amplifier from the input port to the output port; and a residual gain monitor operable to provide a probe laser beam, the probe laser beam travelling along a probe beam path through the laser amplifier from the output port to the input port, wherein the residual gain monitor calculates a residual gain of the laser amplifier according to the probe laser beam.

Abstract: A method may comprise relaying a wireless signal via a bi-directional, full-duplex relay. The relay may comprise an analog uplink relay and an analog downlink relay, and may relay signals between a transmitter and a backscatter node. The spectrum of the downlink signal transmitted by the downlink relay may be different than the spectrum of the uplink signal received by the uplink relay. Filtering may attenuate leakage from the downlink relay to the uplink relay, and vice versa. The uplink relay may create a phase offset that is opposite in sign and substantially equal in magnitude to the phase offset created by the downlink relay. The downlink and uplink relays, taken together, may create a substantially constant net phase offset. The full-duplex relay may be housed in a vehicle that moves, and may be used to determine spatial coordinates of backscatter sources that are located in the relay's environment.

Abstract: An apparatus is provided that can estimate a transfer function, for example of current measurement systems, voltage measurement systems and power measurement systems, and also provide an estimate of certainty about the transfer function. This enables customers to have confidence that they are not being overcharged for electricity.

Abstract: A control apparatus is used in a display apparatus. The control apparatus includes a laser element; a temperature sensor configured to detect a temperature of the laser element; a laser driver configured to drive the laser element; and a laser control unit configured to control a driving current to be supplied to the laser element by the laser driver, such that an optical output value of the laser element converges to a target optical output value. The laser control unit determines an initial driving current value that causes an initial optical output value to be output from the laser element, based on temperature characteristic data of the initial driving current value, and a detection temperature of the laser element detected by the temperature sensor, and controls the driving current to start from the determined initial driving current value.

Abstract: A full-duplex analog relay may comprise an analog uplink relay and an analog downlink relay, and may relay signals between a transmitter and a backscatter node. The spectrum of the downlink signal transmitted by the downlink relay may be different than the spectrum of the uplink signal received by the uplink relay. Filtering may attenuate leakage from the downlink relay to the uplink relay, and vice versa. The uplink relay may create a phase offset that is opposite in sign and substantially equal in magnitude to the phase offset created by the downlink relay. The downlink and uplink relays, taken together, may created a substantially constant net phase offset. The full-duplex relay may be housed in a vehicle that moves, and may be used to determine spatial coordinates of backscatter sources that are located in the relay's environment.

Abstract: A low-cost, robust method for automatically tuning a coupled resonator to match a wavelength of electromagnetic radiation emitted from an applied laser source. Dithering signals are used for automatic wavelength tuning and thermal stabilization of microring resonators. The disclosed method can be applied using low-speed analog and digital circuitry, to create a complete photonic interconnection network. The methods disclosed also automatically detect, measure, and correct for resonance shift.

Abstract: A technique for optical signal transmission includes generating a plurality of double sideband modulated optical signals by modulating a plurality of source data signals using a plurality of direct modulation laser (DML) optical sources, wherein the plurality of double sideband modulated optical signals occupy non-overlapping neighboring optical frequency bands, generating a chirp-managed laser (CML) output signal by multiplexing the plurality of double sideband modulated optical signals using a wavelength-selective multiplexer, and transmitting the CML output signal over an optical transport medium.

Abstract: A thermal management system for an object comprising: one or more thermoelectric elements, one or more light emitting sources, electricity transport medium; electrical energy storage, and a controller. Heat energy that is generated or absorbed by the object is converted by said thermoelectric element to electrical energy. This energy is transferred to light emitting source to emit the energy to the environment or delivered to the electrical energy storage or back to the thermoelectric elements using the electricity transport medium and the controller to achieve the thermal goal of the thermal management system.

Abstract: An absorption spectrometer which measures a gas component concentration in a measured gas and which operates via wavelength modulation spectroscopy, wherein the light wavelength of a wavelength-tunable light source is periodically varied over a gas component absorption line of interest and simultaneously sinusoidally modulated with a high frequency and a low amplitude signal, and wherein the measurement signal of a detector is demodulated in a phase-sensitive manner at the frequency and/or a harmonic of the frequency and further analyzed, where modulation starts in each period or each n-th period with the frequency in a time interval before the beginning of the time function and is performed with a higher amplitude than during the time function to demodulate the measurement signal in a phase-synchronous manner, where a device provided for the phase-sensitive demodulation is synchronized during the time interval such that a cable for transmitting synchronization signals is no longer necessary.

Abstract: Provided is a solar-pumped fiber laser device that includes: a first layer of a light guiding material or a fluorescent material having a circular or an elliptical planar contour with an even thickness; and an optical fiber wound around a peripheral thickness edge of the first layer, wherein the optical fiber is irradiated with light formed of solar light having entered a flat surface of the planar contour of the first layer, the solar light being scattered by the light guiding material, or with fluorescence generated by applying the solar light having entered the flat surface of the planar contour of the first layer to the fluorescent material.

Abstract: Wafer positioning errors in stepper-scanners contribute to imaging defects. Changing the wavelength of the light source's generated light can compensate for wafer positional errors in the Z-direction. The wafer's real-time z-position is determined and a change in wavelength target to offset this error is communicated to the light source. The light source uses this change in wavelength target in a feed-forward operation and, in an embodiment, in combination with existing feedback operations, on a pulse-by-pulse basis for subsequent pulses in a current burst of pulses in addition to receiving the newly-specified laser wavelength target for a subsequent burst of laser pulses.

Abstract: An optoelectronic component for generating and radiating an electromagnetic signal exhibiting a frequency lying between 30 GHz and 10 THz referred to as a microwave frequency, comprises: a planar guide configured to confine and propagate freely in a plane XY a first and a second optical wave exhibiting an optical frequency difference, referred to as a heterodyne beat, equal to the microwave frequency, a system for injecting the optical waves into the planar guide, a photo-mixer coupled to the planar guide to generate, on the basis of the first optical wave and of the second optical wave, a signal exhibiting the microwave frequency, the photo-mixer having an elongated shape exhibiting along an axis Y a large dimension greater than or equal to half the wavelength of the signal, the injection system configured so that the optical waves overlap in the planar guide and are coupled with the photo-mixer over a length along the axis Y at least equal to half the wavelength of the signal, the photo-mixer thus being abl

Abstract: Apparatus and methods for fluorescence imaging using radiofrequency multiplexed excitation. One apparatus splits an excitation laser beam into two arms of a Mach-Zehnder interferometer. The light in the first beam is frequency shifted by an acousto-optic deflector, which is driven by a phase-engineered radiofrequency comb designed to minimize peak-to-average power ratio. This RF comb generates multiple deflected optical beams possessing a range of output angles and frequency shifts. The second beam is shifted in frequency using an acousto-optic frequency shifter. After combining at a second beam splitter, the two beams are focused to a line on the sample using a conventional laser scanning microscope lens system. The acousto-optic deflectors frequency-encode the simultaneous excitation of an entire row of pixels, which enables detection and de-multiplexing of fluorescence images using a single photomultiplier tube and digital phase-coherent signal recovery techniques.

Abstract: Frequency independent isolation of duplexed ports in distributed antenna systems (DASs) is disclosed. Instead of providing a duplexer in a DAS that provides frequency dependent separation between downlink and uplink communications signals, an isolation circuit is provided. The isolation circuit is coupled to a duplexed port that provides downlink communications signals to the DAS and receives uplink communications signals from the DAS. To isolate uplink communications signals from the downlink communications path, the isolation circuit includes a directional coupler. The directional coupler provides frequency independent isolation between uplink communications signals and a downlink communications path in the DAS. Further, to isolate downlink communications signals from the uplink communications path, the isolation circuit includes at least one circulator isolator.

Abstract: A laser source or a plurality of laser sources in a photonic integrated circuit (PIC) are provided with an electrical contact that is either segmented or is connected to a series of vernier resistor segments for supply of current to operate the laser source. In either case, at least one segment of the laser contact or at least one vernier resistor segment can be trimmed in order to vary the amount of current supplied to the laser source resulting in a change to its current density and, thus, a change in its operational wavelength while maintaining the current supplied to the laser source constant.

Abstract: In various embodiments, wavelength beam combining laser systems incorporate etalons to establish external lasing cavities and/or to combine multiple input beams into a single output beam.

Abstract: A laser-frequency stabilizer includes: a light detector that converts a laser beam passing through an iodine cell to an optical output signal, an actuator that changes a resonator length in accordance with a received output voltage, and a control unit that controls the output voltage applied to the actuator. The control unit searches for a target saturated absorption line based on the optical output signal and, when the output voltage when the target saturated absorption line is found is within a normal voltage range that is predetermined corresponding to the target saturated absorption line, locks a oscillation frequency of the laser beam to the target saturated absorption line.

Abstract: A control apparatus for a laser oscillator includes an abnormality determining unit which determines an abnormality of a first assembly based on a first deviation between a first laser beam output command and a first laser beam output and which determines an abnormality of a second assembly based on a second deviation between a second laser beam output command and a second laser beam output, a command unit for issuing a predetermined current command to at least one of a first power unit and a second power unit when the abnormality determining unit determines that at least one of the first assembly and the second assembly has an abnormality, and an abnormality determination stopping unit for stopping the abnormality determining unit from determining an abnormality when the predetermined current command is issued.

Abstract: Optical coherence tomography (OCT) probe and system designs are disclosed that minimize the effects of mechanical movement and strain to the probe to the OCT analysis. It also concerns optical designs that are robust against noise from the OCT laser source. Also integrated OCT system-probes are included that yield compact and robust electro-opto-mechanical systems along with polarization sensitive OCT systems.

Abstract: Transducers and methods for converting acoustic signals into electrical signals. A device (100) includes an interferometer (106) including two mirrors (108) adapted for reflecting electromagnetic radiation (112) coupled into a space (110) between the mirrors (108). The acoustic signal (102) is to be coupled into the space (110) for influencing the electromagnetic radiation (112) in accordance with this acoustic signal. An electromagnetic radiation detector (112) is adapted for detecting the influenced electromagnetic radiation (112) and for converting the detected influenced electromagnetic radiation (112) into the electric signal (104) being indicative for the acoustic signal (102). An operation point stabilization unit stabilizes an operation point of the device (100).

Abstract: In the method of generating high power light with high efficiency and low thermal loading, the improvement comprising the steps of resonantly pumping a first thulium-doped fiber laser with a second thulium-doped fiber last, said second thulium-doped fiber laser having a shorter wavelength than said first thulium-doped fiber laser.

Abstract: A resonator fiber optic gyroscope comprises a master laser that emits a reference optical signal, a first slave laser that emits a clockwise optical signal, and a second slave laser that emits a counter-clockwise optical signal. A resonator ring cavity in optical communication with the first slave laser and second slave laser is configured to receive the optical signals from the slave lasers without receiving the reference optical signal. A reflected optical signal from the cavity is directed to a feedback laser stabilization loop for the master laser that includes a common modulation frequency scheme. A frequency of the optical signal from the master laser is indirectly locked onto a resonance frequency of the cavity with a fixed frequency offset, which is determined by a relative frequency between the optical signal of the first slave laser or the second slave laser, and the optical signal of the master laser.

Abstract: A device may insert a set of tones into a transmitter signal at a set of frequency offsets from a set of transmitter channels associated with a set of transmitter channel wavelengths. The set of transmitter channels may include a first channel being associated with a first quantity of bandwidth and a second channel associated with a second quantity of bandwidth. The first quantity of bandwidth may be different from the second quantity of bandwidth. The device may repeatedly adjust the transmitter signal to align the set of transmitter channel wavelengths based on a set of observed responses to the set of tones, generated based on the transmitter signal passing through an optical filter, failing to match a set of expected responses.

Abstract: A laser system including a pressure adjusting part adjusting the laser gas pressure in the laser gas container, a pressure control unit controlling the pressure adjusting part so that before startup of the laser oscillator, the laser gas pressure becomes a first gas pressure lower than atmospheric pressure and so that at a preparatory stage after startup of the laser oscillator and before radiation of the laser light, the laser gas pressure becomes a second gas pressure capable of oscillating laser light, a laser control unit controlling the laser oscillator so that the laser oscillator executes an initial operation, a laser detector detecting the laser light output by the initial operation, and a hermetic seal estimating part estimating an extent of hermetic seal of the laser gas container based on a detection value obtained by the laser detector.

Abstract: The present invention relates to a gas cell (1) for optical measurements of gas content and/or concentration comprising a cavity (1a), at least one aperture (11) for gas exchange, at least one first socket (12) for light emitting means (2) and at least one second socket (13) for light detecting means (3). The length of an optical measuring path (A) through the cavity (1a) is defined by a direct or indirect distance between a light emitting means (2) in the first socket (12) and a light detecting means (3) in the second socket (13). The present invention teaches that an epoxy mold compound is used to form at least the parts of the gas cell (1) that define the optical measuring path (A).

Abstract: We disclose an optical transponder, in which one or more all-electronic feedback paths are used to obtain a relatively accurate estimate of the device-specific signal distortions in the transmitter portion thereof. The obtained estimate is used to enable the digital signal processor of the optical transponder to carry out electronic pre-distortion (EPD) that can significantly reduce or cancel these signal distortions without the use of detailed factory-calibration measurements or optics dedicated to feedback purposes. The use of all-electronic feedback paths may enable a beneficial reduction in the cost of the EPD functionality, e.g., by eliminating a significant extra cost associated with the implementation of optically generated feedback.

Abstract: A method of controlling a wavelength tunable laser to control an oscillation wavelength based on a difference between a detection result of a wavelength by a wavelength detecting unit and a target value, the method includes: acquiring a first drive condition of the wavelength tunable laser to make the wavelength tunable laser oscillate at a first wavelength from a memory; calculating a second drive condition to drive the wavelength tunable laser at a second wavelength by referring to the first drive condition and a wavelength difference between the first wavelength and the second wavelength, the second wavelength differing from the first wavelength; and driving the wavelength tunable laser based on the second drive condition calculated at the calculating of the second drive condition.

Abstract: Provided are an optical element and a wavelength monitor capable of detecting a wavelength with high accuracy and at high speed while suppressing a size. The optical element includes: a branch waveguide section configured to branch an input light beam and generate two outputs routed via paths having mutually different optical path lengths; and an optical synthesis section configured to synthesize the two outputs and output two optical signals having different light intensities with regards to a wavelength of the input light beam and exhibiting a mutual phase difference.

Abstract: A ring laser gyroscope comprises a laser block that defines an optical closed loop pathway configured to contain a lasing gas. A plurality of mirror structures are respectively mounted on the laser block, with each of the mirror structures having a respective reflective surface that is in optical communication with the optical closed loop pathway. A plurality of electrodes are coupled to the laser block, with the electrodes configured to generate a pair of counter-propagating laser beams from the lasing gas in the optical closed loop pathway. At least one optical sensor is coupled to one of the mirror structures, with the optical sensor in optical communication with the closed loop pathway. A polarizer is in optical communication with the optical sensor. The polarizer is configured to pass laser light having substantially one polarization mode to the optical sensor.

Abstract: Described herein are methods, systems, and apparatuses to utilize a laser device comprising a gain section, a wavelength filter, a first reflector, and a second reflector to form a laser cavity with the first reflector, the laser cavity to include the gain section and the wavelength filter. The wavelength filter is temperature stabilized to a predetermined temperature range and the remaining portions of the laser cavity are not temperature stabilized. The wavelength filter, when at the predetermined temperature range, comprises a plurality of adjacent longitudinal modes such that a difference in modal gain values associated with each of the adjacent longitudinal modes is within a predetermined delta. Thus, the cavity of the laser device is designed to experience some mode hops when the device temperature changes; however, because the wavelength filter is stabilized in temperature, the cavity drift due to these mode hops is within a limited range.

Abstract: To achieve stable multimode output even when driven by a drive current near a threshold value, provided is a laser apparatus comprising a semiconductor laser element; a wavelength selecting element that performs laser oscillation by forming a resonator between itself and a reflective surface of the semiconductor laser element to output oscillated laser light; and an optical system that is optically coupled to an emission surface of the semiconductor laser element with a coupling efficiency ? and inputs to the wavelength selecting element light output from the emission surface. The optical system causes a value that is correlated with a minimum light output within a linear light output region in which light output is linear with respect to an injection current injected to the semiconductor laser element to be less than this value occurring when the coupling efficiency ? is at a maximum.

Abstract: A semiconductor optical element and an optical module in which extinction ratio variation among integrated optical modulation elements is reduced. An optical module has a wavelength multiplexer that multiplexes light respectively emerging from electric-field-absorption modulator (EAM) portions of integrated optical modulation elements, and that outputs the multiplexed light. The integrated optical modulation element has a signal input terminal, a laser element portion, and an EAM portion. Each of the integrated optical modulation elements has a difference between an oscillation wavelength and a barrier layer bandgap wavelength, represented as an LDBG wavelength difference. Variation of the LDBG wavelength differences is limited within a range of ±1 nm.

Abstract: Embodiments of an ultra-stable frequency reference generating system and methods for generating an ultra-stable frequency reference using a two-photon Rubidium transition are generally described herein. In some embodiments, a cavity-stabilized reference laser comprising a laser source is locked to a stabilized cavity. A Rubidium cell is interrogated by a stabilized laser output to cause at least a two-photon Rubidium transition and a detector may detect fluorescence resulting from spontaneous decay of the upper state Rubidium transition. The output of the detector is provided at a wavelength of the fluorescence to lock the cavity-stabilized reference laser to generate a stabilized laser output. A frequency comb stabilizer may be locked to the stabilized laser output to generate a super-continuum of optical wavelengths for use in generating an ultra-stable frequency reference.

Abstract: A passively athermal photonic system including a photonic circuit having a substrate and an optical cavity defined on the substrate, and passive temperature-responsive provisions for inducing strain in the optical cavity of the photonic circuit to compensate for a thermo-optic effect resulting from a temperature change in the optical cavity of the photonic circuit. Also disclosed is a method of passively compensating for a temperature dependent thermo-optic effect resulting on an optical cavity of a photonic circuit including the step of passively inducing strain in the optical cavity as a function of a temperature change of the optical cavity thereby producing an elasto-optic effect in the optical cavity to compensate for the thermo-optic effect resulting on an optical cavity due to the temperature change.

Abstract: A laser system comprising a laser configured to generate a laser beam, a power supply arranged to provide a drive power to the laser, a photodetector arranged to detect the power of the laser beam and provide a detection signal from the power of the laser beam and a feedback loop arranged to form a feedback signal by subtracting a target signal from the detection signal wherein the feedback signal has a high bandwidth, amplify the feedback signal and adjust the drive power according to the amplified feedback signal, thereby reducing noise in the laser beam.

Abstract: A semiconductor laser module includes: a semiconductor laser element having at least one semiconductor laser; a first support member on which the semiconductor laser element is mounted; a first temperature-adjusting element adjusting a temperature of the first support member; a semiconductor optical element having a semiconductor optical amplifier amplifying a laser light outputted from the semiconductor laser element; and a second support member on which the semiconductor optical element is mounted.

Abstract: An object of the present invention is to provide a noninvasive constituent concentration measuring apparatus and constituent concentration measuring apparatus controlling method, in which accurate measurement can be performed by superimposing two photoacoustic signals having the same frequency and reverse phases to nullify the effect from the other constituent occupying large part of the object to be measured. The constituent concentration measuring apparatus according to the invention includes light generating means for generating two light beams having different wavelengths, modulation means for electrically intensity-modulating each of the two light beams having different wavelengths using signals having the same frequency and reverse phases, light outgoing means for outputting the two intensity-modulated light beams having different wavelengths toward a test subject, and acoustic wave detection means for detecting an acoustic wave generated in the test subject by the outputted light.

Abstract: The invention describes a new method of tuning a Fabry-Perot resonant etalon, whose length is actively controlled through the frequency of an identical length microwave resonant cavity. The length is tunable over a several micron range with the precision and stability of the microwave source frequency.

Abstract: An tunable optical frequency comb source includes a linear waveguide having an input leg to couple to a pump laser. A ring microresonator is evanescently coupled to the linear waveguide. The microresonator includes a ring shaped waveguide having a core material with a nonlinear refractive index to provide four-wave mixing to generate a cascade of independent laser beams at frequencies corresponding to the longitudinal modes of the microresonator.

Abstract: A method for optimizing startup time and efficiency for a WBC laser diode system having numerous diode elements, wherein each diode element is measured, an optimal band region is determined for each diode element, and placed in an optimal placement within an array of diode elements.

Abstract: A laser apparatus includes an external cavity laser (ECL) where the optical signal is modulated by an electrical modulation signal for modulating in frequency the laser output signal. The modulation in frequency produces a modulation of intensity (power) of the laser output signal, also denoted amplitude modulation (AM). A method of controlling the AM amplitude of a signal emitted by an ECL includes a gain medium, a phase element with variable transmissivity induced by the modulation, and a spectrally selective optical filter that selects and keeps the AM amplitude below a certain desired value or minimizes such value. A control method and a laser apparatus are also described in which the reduction of the AM component of the output power is achieved by acting on the gain of the gain medium of the ECL.

Abstract: An external resonator type light emitting system includes a light source oscillating a semiconductor laser light and a grating device providing an external resonator with the light source. The light source includes an active layer oscillating the semiconductor laser light. The grating device includes an optical waveguide having an incident face to which the semiconductor laser is incident and an emitting face of emitting an emitting light of a desired wavelength, a Bragg grating formed in the optical waveguide, and a propagating portion provided between the incident face and the Bragg grating. Formulas (1) to (4) are satisfied.

Abstract: A laser system includes a seed laser configured to generate a plurality of optical pulses; a controller configured to receive the plurality of the optical pulses and obtain chirped pulses, each chirped pulse having a chirping amount different from each other; an optical waveguide, having a characteristic of anomalous dispersion, configured to cause soliton self-frequency shifts while the chirped pulses propagating so that each center wavelength of a pulse which output from the optical waveguide is different from each other.

Abstract: There is provided a frequency tunable laser system comprising a laser, frequency varying means arranged for varying an optical frequency output of the laser, an intensity sensor arranged for receiving light from the laser, and a processor arranged for controlling the frequency varying means for varying the optical frequency output of the laser and receiving an intensity signal from the intensity sensor for monitoring the intensity output of the laser. The frequency tunable laser system further comprises an external reflective surface, in use, fixedly arranged in a light path of the laser beam outside the laser cavity at a predefined distance from the second reflective surface along the light path of the laser beam to reflect part of the emitted laser beam back into the laser cavity.

Abstract: Described herein are methods, systems, and apparatuses to utilize a laser device comprising a gain section, a wavelength filter, a first reflector, and a second reflector to form a laser cavity with the first reflector, the laser cavity to include the gain section and the wavelength filter. The wavelength filter is temperature stabilized to a predetermined temperature range and the remaining portions of the laser cavity are not temperature stabilized. The wavelength filter, when at the predetermined temperature range, comprises a plurality of adjacent longitudinal modes such that a difference in modal gain values associated with each of the adjacent longitudinal modes is within a predetermined delta. Thus, the cavity of the laser device is designed to experience some mode hops when the device temperature changes; however, because the wavelength filter is stabilized in temperature, the cavity drift due to these mode hops is within a limited range.