Abstract: Implementations and examples of mode-locked fiber lasers based on fiber laser cavity designs that produce self-similar pulses (“similaritons”) with parabolic pulse profiles with respect to time at the output of the fiber gain media to effectuate the desired mode locking operation. An intra-cavity narrowband optical spectral filter is included in such fiber lasers to ensure the proper similariton conditions.

Abstract: Method for calibrating and tuning a part wise monotonically, continuously tunable semiconductor laser having a phase section and a first Bragg reflector section, through which sections a phase current and a first reflector current, respectively, are applied, which laser is not actively cooled, includes a) a calibration step, including obtaining at least two tuning lines along which tuning lines all combinations of phase and Bragg currents are stable operating points, identifying at least one reference stable operating point along a first one of the identified tuning lines at which operating point the laser emits light at a certain reference frequency, and storing at least one reference stable operating point; and b) a subsequent tuning step, during which the output frequency of the laser in relation to the reference frequency is controlled to a desired output frequency by translating the operating point of the laser along the first tuning line.

Abstract: A tunable laser includes a resonator including a highly reflecting mirror and a partially reflecting mirror; a gain medium disposed in the resonator; a birefringence filter disposed in the resonator; and an excitation device that excites the gain medium. In the tunable laser, light that passes through the birefringence filter oscillates between the highly reflecting mirror and the partially reflecting mirror. An oscillation wavelength is switched by rotating the birefringence filter. The birefringence filter includes a first birefringent plate and a second birefringent plate, which have principal dielectric axes parallel to optical surfaces thereof. An absolute value of an angle formed by the principal dielectric axis of the first birefringent plate and the principal dielectric axis of the second birefringent plate is larger than zero.

Abstract: A variable wavelength diode according to the inventive concept includes a resonator and a plurality of cylindrical lenses. The resonator includes slab waveguides of which resonance lengths are different from each other. The slab waveguides are disposed on a planar light wave circuit (PLC). Thus, the variable wavelength diode realizes a high variation speed and a continuous variation of a beam at the same time.

Abstract: The present invention uses a laser apparatus capable of selecting a wavelength of light to be outputted from a plurality of wavelengths, including: a branching unit which is formed of a polarizer and is configured to branch an optical path formed in a resonator including a reflecting unit having a plurality of fixed reflecting planes and an output mirror, into a plurality of optical paths, thereby forming a common optical path having an end defined by the output mirror and a plurality of optical path branches each having an end defined by any one of the reflecting planes; a laser medium disposed in the common optical path; and a selecting unit configured to select, from the plurality of optical path branches, an optical path branch which corresponds to a wavelength of light to be outputted.

Abstract: An apparatus comprising a silicon-on-insulator (SOI) platform comprising an optical component network. An apparatus comprising an optical component network monolithically grown on a SOI platform, and an optical device coupled to the optical component network. A method comprising generating an optical signal using a silicon-based optical component, applying an electrical signal to the optical component, and tuning a wavelength of the optical signal based on the electrical signal.

Abstract: Provided is a power saving and highly reliable wavelength tunable laser device. A wavelength tunable laser device 10 of the present invention includes: a wavelength tunable laser 11 including: a laser resonator including a light source 111 and wavelength tunable mechanisms 112 and 113; and light loss control units 114a and 114b; a temperature detecting element 12 detecting a temperature of the wavelength tunable laser 11; and a controller 13, wherein the controller 13 obtains temperature information a of the wavelength tunable laser 11 from the temperature detecting element 12, calculates wavelength tunable control parameters d and e and light loss control parameters b1 and b2 based on the temperature information a, controls the wavelength tunable mechanisms 112 and 113 based on the wavelength tunable control parameters d and e, and controls light loss control units 114a and 114b based on the light loss control parameters b1 and b2.

Abstract: Systems and methods of the invention generally relate to feedback loops for wavelength stabilization. According to certain aspects, a method of the invention includes filtering light through a tunable filter configured to deliver a target wavelength of light, measuring the wavelength of the filtered light, detecting a change between the target wavelength and the filtered wavelength, and adjusting the tunable filter based on the detected change so that the filtered wavelength matches the target wavelength.

Abstract: A microelectromechanical systems (MEMS)-tunable vertical-cavity surface-emitting laser (VCSEL) in which the MEMS mirror is a bonded to the active region. This allows for a separate electrostatic cavity, that is outside the laser's optical resonant cavity. Moreover, the use of this cavity configuration allows the MEMS mirror to be tuned by pulling the mirror away from the active region. This reduces the risk of snap down. Moreover, since the MEMS mirror is now bonded to the active region, much wider latitude is available in the technologies that are used to fabricate the MEMS mirror. This is preferably deployed as a swept source in an optical coherence tomography (OCT) system.

Abstract: A laser device (100) includes a laser (110; 210; 310; 410; 510) in turn including at least one Distributed Bragg Reflector (DBR) section (111), at least one phase section (112) and at least one gain section (113), further including a laser control element (150), a feedback control element (140) and a frequency noise discriminator (130,131), which feedback control element is arranged to feed a variable feedback signal to at least one of the at least one DBR section and the at least one phase section of the laser, so that the output laser frequency is altered in response to a variation in the feedback signal or the combination of respective feedback signals, whereby the feedback signal or combination of respective feedback signals is varied as a function of the detected frequency fluctuation so as to counteract the detected frequency fluctuation.

Abstract: A frequency-doubled OPS-laser having a desired output wavelength of 532 nm is tunable about that wavelength by a temperature tuned birefringent filter (BRF). The temperature of the BRF is varied while measuring transmission of a sample of the output through a Nd:YAG crystal having an absorption peak at a wavelength of about 532.4 nm. The peak is detected as a minimum of transmission and the temperature at which that minimum occurs is recorded. From wavelength-change-versus-temperature data for the BRF a temperature is calculated at which the output wavelength has the desired value and is maintained at that value to stabilize the output wavelength.

Abstract: The invention relates to a method for generating coherent-phase light having a predefinable frequency value (?Soll), comprising the steps of generating working light with a working frequency (?SL), generating a frequency comb (10), which is a light field that consists of equidistant coherent-phase spectral lines, selecting a comb line (having the index m) from the frequency comb (10) having a frequency (?m), generating a frequency shift (??) of the frequency comb (10) and/or the working frequency (?SL) by means of time-dependent phase settings (?S(t)) modulo a multiple of 2?, in particular of 2?, and phase-coupling the possibly frequency-shifted fields of the working light (?SL) and the one possibly frequency-shifted frequency comb line (?m), so that the frequencies thereof are rigidly phase-coupled via the frequency shift (??), and working light having the desired frequency (?Soll) is obtained.

Abstract: The optical source apparatus includes a deflector that includes a first deflector and a second deflector which deflect the light emitted from the gain medium in a first direction and a second direction, respectively, and a wavelength selection element that has a first region and a second region which select light having any wavelength in a first wavelength range and a second wavelength range out of the light illuminating the wavelength selection element through the deflector, respectively, wherein the first region is structured so that the wavelengths of light selected along the first direction are different from each other, the second region is structured so that the wavelengths of light selected along the first direction are different from each other, and the second region is positioned in the second direction with respect to the first region.

Abstract: According to an embodiment of the present invention, an optical parametric oscillator (OPO) (e.g., for a laser transmitting device) includes non-linear optical media, optical beam manipulating elements, and a narrow linewidth filter in the form of a rotatable grating. The grating enables rapid tuning of the oscillator to provide an output beam with a desired wavelength. A pump laser provides a pump laser beam, and the non-linear optical media convert the pump beam into light beams with a signal wavelength and an idler wavelength. The angular positions or orientations of the non-linear optical media relative to a longitudinal propagation axis of the optical parametric oscillator (OPO) are adjustable to effectively tune the resulting signal and idler wavelengths. An output coupler receives the resulting beams from the non-linear optical media, and emits beams with the desired wavelength (signal and/or idler wavelengths).

Abstract: The invention relates to a precision optical frequency tunable laser. The laser includes: a laser gain medium, an intracavity collimating lens, an active optical phase modulator, a tunable acousto-optic filter and an intracavity total reflection mirror all arranged sequentially in a laser cavity, and the tunable laser further includes an active polarization rotator, a polarization beam splitter, two etalons, a temperature control system attached to the etalons, two total reflection mirrors, a radio frequency signal source, a laser pumping source, an active optical phase modulator drive source, an active polarization rotator drive source and a laser drive control circuit. Through the temperature control system attached to the etalons, stable laser output and the precision optical frequency tuning less than 1 GHz within a wide spectrum range can be realized, thereby greatly reducing the bandwidth requirements in achieving narrowband filtering for the tunable acousto-optic filter.

Abstract: A wavelength-tunable optical transmission apparatus including an optical array unit comprising a plurality of light sources whose wavelengths are changed, an optical driving unit configured to receive an electrical signal transmitted from an external circuit, generate the current and input the generated current to the optical array unit, and a control unit configured to control the magnitude of current input to the optical array unit by controlling the optical driving unit.

Abstract: A system and method for passive combination of two or more laser sources (e.g., sampled grating distributed Bragg reflector (SG-DBR) lasers) into a single sweep that encompasses the combined range of the wavelengths of each laser source.

Abstract: A laser apparatus comprises a cavity having an output unit, and a branch unit arranged between the output unit and first and second reflection unit, an optical path in the cavity including a common part and separate parts, respectively; a laser medium and a wavelength filter disposed in the common part; a pump unit configured to pumping the laser medium; and first and second shielding units respectively disposed in the first and second separate parts, the transmittance of the wavelength filter is varied based on the wavelength and polarization of incident light, the branch unit splits a light beam into the first polarized light and the second polarized light, and one of the first and second shielding units being opened and the other closed to select one of the wavelengths of light to be emitted.

Abstract: A method for quasi-synchronous tuning of wavelength or frequency of grating external-cavity semiconductor laser and a corresponding semiconductor laser are provided. A grating or mirror is rotated around a quasi-synchronous tuning point (Pq) as rotation center, so as to achieve the frequency selections by grating and resonance cavity in quasi-synchronous tuning, wherein the angle of the line between the quasi-synchronous tuning point (Pq) and a conventional synchronous tuning point (P0) with respect to the direction of light incident on the grating is determined according to the angle difference between the incidence angle and diffraction angle of light on the grating. According to present invention, approximately synchronous tuning of laser is achieved with a simple and flexible design.

Abstract: Systems and methods are provided for imaging using complex lasers. In general, a complex laser may be used as an electromagnetic source for an imaging application. The use of a lower spatial coherence configured complex laser in imaging applications may advantageously mitigate coherent artifacts in imaging such as cross-talk and speckle and improve overall image quality. Imaging applications where a complex laser may be useful include both incoherent imaging applications, such as digital light projectors and traditional microscopy, and coherent imaging applications, such as optical coherence tomography (OCT) and holography. The systems and methods provided also enable controlling the degree of spatial coherence of a complex laser.

Abstract: A wavelength-tunable light source includes light sources having differing variable wavelength regions, where light sources having adjacent wavelength regions are distributed to different systems. The light sources are each set such that an end portion of the variable wavelength region of the light source overlaps an end portion of the variable wavelength region of another light source. A control unit selects and drives a first light source of a first system, varies a wavelength of the first light source, selects a second light source that is of a second system among the different systems and that has a wavelength region overlapping the variable wavelength region of the first light source, drives the second light source concurrently with the first light source and subsequently switches to the output light of the second light source, causing wavelength variation and executing continuous wavelength variation over a wide range.

Abstract: An optical module includes a light source. The light source can be a swept wavelength light source, and optical module includes a wavemeter. The wavemeter includes a wavemeter tap capable of directing a wavemeter portion of light produced by the light source away from a main beam, a wavelength selective filter arranged to receive the wavemeter portion, a first wavemeter detector arranged to measure a transmitted radiation intensity of radiation transmitted through the filter, and a second wavemeter detector arranged to measure a non-transmitted radiation intensity of radiation not transmitted through but reflected by the filter. In addition, an optical coherence tomography apparatus includes the optical module.

Abstract: The invention relates to an apparatus and a method for referencing an optical frequency of a tunable laser. Light from a reference laser and the tunable laser is injected into a length of an optical waveguide from opposite ends thereof. When the optical frequency of the tunable laser is swept, SBS induced positive and negative peaks in the optical power of light transmitted through the waveguide are used to provide an accurate frequency change reference.

Abstract: A gain clamped optical device includes a semiconductor stack and a resonant cavity configured to emit stimulated light. A window created in the optical device is configured to emit the stimulated light in an LED mode.

Abstract: To improve a laser system comprising at least one externally stabilizable semiconductor laser, from the laser active zone of which a laser radiation field can be coupled out, and a feedback element, disposed externally in the laser radiation field, which couples out, from the laser radiation field, a feedback radiation field having a defined wavelength and bandwidth, and couples back same into the active laser zone for determining the wavelength and bandwidth of the laser radiation field, in such a way that the wavelength stabilization may be achieved more cost-effectively, it is proposed that the feedback element is a resonant waveguide grating which reflects back a portion of the laser radiation field lying within an angular acceptance range.

Abstract: A method for quasi-synchronous tuning of laser wavelength or frequency of grating external-cavity laser and a corresponding laser are provided. A grating or mirror is rotated around a quasi-synchronous tuning point (Pq) to achieve the quasi-synchronous tuning of frequency selections by grating and resonance cavity, wherein, on the xOy coordinate plane, from the perspective of actual physical space of the laser, the rotation center Pq(xq, yq) satisfying the quasi-synchronous tuning condition can be considered as being extended from the rotation center P0(x0, y0) under the conventional synchronous tuning condition to the region enclosed by two parabolas near P0. According to the present disclosure, approximately-synchronous tuning of laser is achieved with simple and flexible designs.

Abstract: A method for tuning a semiconductor laser including a plurality of wavelength selection portions, each of which has a periodic wavelength characteristic, including: controlling a value of a refractive index controlling means of the wavelength selection portions to achieve a desired output wavelength of the laser; and shifting the value when the value is equal to or excess of a predetermined value to a basal value side until achieving the desired output wavelength, the basal value being a value without applying refractive index variation by the refractive index controlling means, the predetermined value being a value for shifting one period of the periodic wavelength characteristic.

Abstract: A tunable optical system with hybrid integrated semiconductor laser is provided. The optical system includes a silicon-on-insulator (SOI) substrate; a first optical waveguide tunable comb filter formed at the first side of the SOI substrate; a second optical waveguide tunable comb filter with detuned filter response formed at the first side of the SOI substrate; an etched laser pit at the first side of the SOI substrate; a plurality of spacers formed on the bottom surface of the laser pit near the plane of the first side of the SOI substrate; a plurality of bumping pads formed on the bottom surface of the laser pit near the plane of the first side of the SOI substrate; and a laser chip flip-chip bonded at the first side of the SOI substrate supported by the spacers. Heating sections may be provided on the filters to tune the filters.

Abstract: Systems and methods are disclosed that provide a direct indication of the presence and concentration of an analyte within the external cavity of a laser device that employ the compliance voltage across the laser device. The systems can provide stabilization of the laser wavelength. The systems and methods can obviate the need for an external optical detector, an external gas cell, or other sensing region and reduce the complexity and size of the sensing configuration.

Abstract: A master oscillator system may include a grating configured to function as one resonator mirror in an optical resonator, a spectral bandwidth tuning unit configured to tune the spectral bandwidth of a laser beam transmitted within the optical resonator, a storage unit configured to store a control value of the spectral bandwidth tuning unit corresponding to a desired spectral bandwidth and a controller configured to control the spectral bandwidth tuning unit based on the control value stored in the storage unit.

Abstract: A tunable laser includes an optical cavity comprising a first and second mirror. A gain medium is positioned in the optical cavity that generates stimulated emission in the optical cavity when biased. A thermally tunable optical filter is positioned in the optical cavity that is heated to a temperature that selects a desired optical mode of the optical cavity. A thermally tunable optical phase retarder is positioned in the optical cavity that is heated to a temperature which changes an optical path length in the optical cavity by an amount corresponding to a resonant frequency of the tunable optical filter so that a phase-matching condition of the optical cavity is shifted to the desired optical mode of the optical cavity selected by the thermally tunable optical filter.

Abstract: The present disclosure relates to a compact external cavity tunable laser apparatus. The laser apparatus includes a substrate, an external cavity tunable reflecting unit that reflects laser light entering from the outside on the substrate and selects and varies a wavelength of the reflected laser light, an optical fiber that outputs the laser light on the substrate; and an highly integrated light source that integrates the laser light input from the external cavity tunable reflecting unit using inclined input and output waveguides, a curved waveguide, and a straight waveguide to output the integrated laser light to the optical fiber in order to match an optical axis formed with the external cavity tunable reflecting unit with an optical axis formed with an optical fiber.

Abstract: A semiconductor laser module includes a semiconductor device including a semiconductor laser and a bending waveguide through which a laser light emitted from the semiconductor laser propagates, a beam splitter splitting the laser light into a first laser light and a second laser light, a plurality of detectors respectively arranged at different positions in a cross section of a light flux of the second laser light to detect the second laser light, and a waveform shaping unit provided on an optical path of the laser light. The waveform shaping unit is configured to make a relation between an output of the semiconductor laser and detection values of the detectors approach a linear relation.

Abstract: Method for calibrating a tunable semiconductor laser having a phase section and a first Bragg reflector section, through which sections a phase current and a first reflector current, respectively, is applied, includes: a) selecting a phase current; b) identifying a range of reflector currents that achieves emission of light from the laser within a desired frequency band; c) scanning the reflector current(s) over the range of reflector currents, for each of at least two different phase currents, and reading the relative output power of the laser for each point scanned; d) identifying one stable operating point; e) identifying and storing one stable, continuous tuning line as constructed by interpolating; f) calibrating the laser frequency and observing a fed back signal from a target for the light emitted from the laser; g) measuring the temperature of the laser; and h) storing temperature and one operating point along the tuning line.

Abstract: A discretely tunable locally seeded laser device is provided. The discretely tunable locally seeded laser device comprises: a first tunable laser comprising first discrete output modes; and, a second tunable laser arranged to receive output from the first tunable laser, but otherwise optically isolated from the first tunable laser, the second tunable laser comprising second discrete output modes, such that one first discrete output mode can optically seed an aligned second discrete output mode in a given position of one or more of the first discrete output modes and the second discrete output modes, the aligned second discrete output mode comprising a dominant output.

Abstract: A discretely tunable laser device is provided. The discretely tunable laser device comprises: a laser comprising a plurality of discrete output modes; an optical filter for receiving output from the laser but otherwise optically isolated from the laser, the optical filter comprising a plurality of transmission peaks, each separated by a transmission spacing different from a spacing of the plurality of discrete output modes such that only one discrete output mode can predominantly align with one transmission peak when the plurality of discrete output modes are tuned; and, a control apparatus for tuning the discrete output modes of the laser to align a given output mode of the plurality of discrete output modes with a given transmission peak of the plurality of transmission peaks, such that the given output mode comprises a dominant output of the optical filter.

Abstract: In aspects of the invention, wavelength conversion element has a harmonic generation portion and a parametric oscillation portion. The harmonic generation portion generates a harmonic of laser light output from a laser light source. The parametric oscillation portion generates signal light and idler light from the harmonic generated by the harmonic generation portion. In some aspects of the invention, electrodes and a first voltage control portion control the intensity of the harmonic generated by the harmonic generation portion. A first FBG (Fiber Bragg Grating) and a second FBG cause resonance of signal light output from the parametric oscillation portion. A piezo tube and a second voltage control portion change the resonance frequency of the first FBG and the second FBG.

Abstract: In one embodiment, the invention relates to systems, methods and devices for improving the operation of an electromagnetic radiation source or component thereof. In one embodiment, the source is a laser source. A Fourier domain mode locked laser can be used in various embodiments. The sources described herein can be used in an optical coherence tomography (OCT) system such as a frequency domain OCT system. In one embodiment, laser coherence length is increased by compensating for dispersion. A frequency shifter can also be used in one embodiment to compensate for a tunable filter induced Doppler shift.

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: A laser apparatus includes a laser medium; a light source that radiates light to the laser medium, thereby exciting the laser medium and raising the temperature thereof; a reflecting unit having a first plane that reflects light within a predetermined wavelength range from light generated by excitation of the laser medium; and an output mirror disposed opposite the reflecting unit, with the laser medium being interposed therebetween, and causing laser oscillation by inducing resonance of the light within a predetermined wavelength range between the first plane and the output mirror. The reflecting unit is configured to be movable between a position in which light resonance is induced between the output mirror and the first plane and the laser apparatus is set to an oscillation state and a position in which the laser apparatus is set to a non-oscillation state.

Abstract: Swept source designs that eliminate or significantly reduce artifacts in optical coherence tomography are presented. One embodiment of the present invention is a source design that frequency shifts the coherence revival interference signal to a frequency larger than the A/D detection bandwidth or the post-processing bandwidth. In another embodiment, the introduced frequency shift is large enough to introduce a Doppler shift of the modes of the laser, which causes a blurring of the comb function, and thus eliminates or reduces mode hopping. In another embodiment, adjusting the cavity optical path length prior to data acquisition depending on the given optical layout configuration to reduce or eliminate coherence revival artifacts is described.

Abstract: A wavelength tunable laser diode (LD) is disclosed. The LD provides a SG-DFB region and a CSG-DBR region. The SG-DFB region shows a gain spectrum with a plurality of gain peaks, while, the CSG-DBR region shows a reflection spectrum with a plurality of reflection peaks. The LD may emit light with a wavelength at which the one of the gain peaks and one of the reflection peaks coincides. In the present LD, both the gain spectrum and the reflection spectrum are modified by adjusting the temperature of the SG-DFB region and that of the CSG-DBR region independently.

Abstract: 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.

Abstract: A tunable external cavity laser for use as a pump laser in an optical amplifier such as a Raman amplifier or erbium doped fibre amplifier comprising a semiconductor gain device (12) operable to provide light amplification, a diffraction grating (18) for selecting the wavelength of operation of the laser and a MEMs actuator for changing the selected wavelength. A plurality of gain devices can be coupled together to improve the bandwidth or gain of the optical amplifier.

Abstract: A spatially modulated waveguide Bragg grating mirror is suspended over a substrate by plurality of fingers extending laterally away from the waveguide centerline. The positions of the fingers are coordinated with the positions of crests and valleys of amplitude or phase modulation of the Bragg grating, to avoid disturbing the Bragg grating when it is tuned by heating. When the Bragg grating is heated, the heat flows through the fingers creating a quasi-periodic refractive index variation along the Bragg grating due to quasi-periodic temperature variation created by the heat flow from the grating through the supporting fingers. Due to coordination of the positions of supporting fingers with positions of the crests and valleys of modulation, the optical phase coherence is maintained along the Bragg grating, so that the spectral lineshape or filtering property of the Bragg grating is substantially preserved.

Abstract: Systems and methods are described for reducing coherence effect in narrow line-width light sources through various modulation techniques. The systems and methods can include a narrow line-width laser source with a thermoelectric cooler thermally coupled thereto and a controller communicatively coupled to the thermoelectric cooler. The controller is configured to provide a varied input signal to the thermoelectric cooler to reduce coherence of the narrow line-width laser source by artificially broadening the narrow line-width on a time averaged basis. The systems and methods can also include direct modulation of the narrow line-width laser source. The systems and methods can include a narrow line-width Optical Time Domain Reflectometer (OTDR). The systems and methods can also include direct modulation of the narrow line-width laser source with or without the varied input signal to the thermoelectric cooler.

Abstract: The invention relates to a precision optical frequency tunable laser. The laser includes: a laser gain medium, an intracavity collimating lens, an active optical phase modulator, a tunable acousto-optic filter and an intracavity total reflection mirror all arranged sequentially in a laser cavity, and the tunable laser further includes an active polarization rotator, a polarization beam splitter, two etalons, a temperature control system attached to the etalons, two total reflection mirrors, a radio frequency signal source, a laser pumping source, an active optical phase modulator drive source, an active polarization rotator drive source and a laser drive control circuit. Through the temperature control system attached to the etalons, stable laser output and the precision optical frequency tuning less than 1 GHz within a wide spectrum range can be realized, thereby greatly reducing the bandwidth requirements in achieving narrowband filtering for the tunable acousto-optic filter.

Abstract: A method to tune an emission wavelength of a wavelength tunable LD is disclosed. The wavelength tunable LD includes two regions each providing micro heaters to modify the refractive index of micro regions provided with power. The method periodically detects a difference between the emission wavelength and the target wavelength. This wavelength difference is converted into power next supplied to respective micro heaters independently.

Abstract: A low white frequency noise tunable semiconductor laser source is presented. The laser source includes a single-mode semiconductor laser assembly which generates a laser beam having a tunable frequency over a spectral range of interest. An optical filter is provided in the path of the laser beam. The optical filter has multiple spectral features distributed over the entire spectral range of interest. Each spectral feature has a narrow spectral range. A locking mechanism is further provided and is controllable for locking a spectral alignment between the frequency of the laser beam and any selected one of the spectral features of the optical filter.

Abstract: A method to tune an emission wavelength of a laser diode (LD) finely is disclosed. The method first controls a temperature of the etalon filter in T1 or T2, where the transmittance of the etalon filter becomes 40 to 50%, assuming a height between the peak and the bottom of the periodic transmittance to be 100%, at the grid wavelength ?1 or ?2, respectively. Then, the temperature of the LD is adjusted such that the intensity of light emitted from the LD and transmitted through the etalon filter becomes 40 to 50%.