63 results about "Mode hopping" patented technology

The invention provides a mode-hopping-free large-range continuous tunable external cavity semiconductor laser, which comprises a laser diode (1), a collimating lens (2), a polarization splitting prism (3), a narrow-band interference sheet (4), a prism-type super-strong-level reflective film (5) and a piezoelectric module (6), the laser diode (1), the collimating lens (2) and the polarization splitting prism (3) are sequentially arranged on a light path, and the narrow-band interference sheet (4), the prism-type super-strong-level reflective film (5) and the piezoelectric module (6) are bonded together. The rotation axis is located on the light path of the laser and coincides with the rear surface of the piezoelectric module (6). According to the mode-hopping-free large-range continuous tunable external cavity semiconductor laser, the sensitivity of the laser frequency to the rotation angle of the narrow-band interference sheet is utilized, and the angle and the cavity length of the interference sheet are changed at the same time, so that the transmission peak center frequency of the interference sheet and the specific cavity mode frequency are highly synchronized along with the change of the angle; according to the laser, mode hopping of the laser output frequency is avoided, and continuous tunability of the output frequency along with the rotation angle of the cavity mirror is guaranteed.

The invention discloses an automatic laser control system and method based on LRC, and belongs to the technical field of automatic laser control, and the system comprises an intra-cavity light reflection existence judgment module, a laser first adjustment module, a mode jump sensitive area judgment module and a laser stability re-judgment module. Real-time monitoring and intelligent judgment of the operation state of the laser can be achieved, working parameters and control strategies of the laser are dynamically adjusted according to key influence factors such as intracavity light reflection and mode jump sensitive areas, the laser output stability and the light beam quality are improved, mode interference and jump risks are reduced, and the laser quality is improved. And the automation level and reliability of the system are improved.

The invention belongs to the technical field of quantum precision measurement, and particularly discloses a frequency stabilization system and a frequency stabilization method for an external cavity semiconductor laser. The system comprises a saturated absorption spectrum module, a wavelet peak searching module, a modulation and demodulation module, a bias amplification module and a switch module, wherein the saturated absorption spectrum module outputs an electric signal of a saturated absorption spectrum; under the control of the frequency locking instruction, the wavelet peak searching module outputs a target bias voltage signal corresponding to the locking frequency based on the electric signal; the modulation and demodulation module performs signal modulation and demodulation based on the electric signal and a reference signal corresponding to the locking frequency to output a modulation signal and a demodulation signal; and the bias amplification module performs superposition and amplification processing on the modulation signal, the demodulation signal and the target bias voltage signal, and outputs a target superposition signal to a PZT modulation port of the laser, so that the output laser freely operates on the locking frequency. According to the invention, the laser is not liable to generate mode hopping in the frequency locking process, the whole frequency stabilization system is more stable, the structure is simple, and the cost is low.

The invention provides a small-angle measuring reference device based on interference frequency selection and microprism array feedback, which comprises a laser generating device and a beat frequency measuring module, and is characterized in that a narrow-band interference sheet (4), a microprism array (5) and a piezoelectric module (6) are fixed on a high-precision horizontal rotating table (7) in parallel; the rear surface of the microprism array (5) is bonded with the front surface of the piezoelectric module (6), and the center of the rear surface of the piezoelectric module (6) is located at the axis position of the rotating table. And when the frequency of the measured laser is changed by delta f, the variable quantity of the beat frequency is equal to delta f. By means of ultrahigh sensitivity of laser frequency to cavity length, the cavity length is changed by rotating the cavity mirror to cause frequency change, then angle measurement is converted into frequency measurement, mode selection is carried out through auxiliary adjustment of the narrow-band interference sheet, cavity mode change and interference frequency selection are highly synchronous, and mode hopping of laser output frequency is avoided. The continuous tunability of the output frequency along with the rotation angle is ensured, and small-angle ultrahigh-precision measurement is realized.

The invention relates to the technical field of optical fiber sensing, in particular to a tunable laser parameter optimization method for fiber bragg grating demodulation, which comprises the following steps of: setting scanning ranges of currents of a left Bragg reflector and a right Bragg reflector, generating a current combination sequence according to arc radius parameters, inputting the current combination into a tunable laser, collecting an output wavelength, and identifying a wavelength tuning channel and a central point thereof; and arranging the center points of the channels in sequence, and generating smooth and continuous channel center lines on the left current dimension and the right current dimension by adopting cubic spline interpolation so as to obtain a continuous and executable tuning path. According to the method, a smooth and continuous channel center line is constructed through a segmented arc scanning path and cubic spline interpolation, and an initial lookup table is formed by combining phase current fine scanning and ordered splicing, so that high-quality wavelength coverage under low sampling amount is realized, and the problems of data redundancy and channel boundary mode hopping in a traditional method are solved.

The invention provides a laser mode hopping detection method and device, relates to the technical field of optical communication, and aims to solve the problems of high cost, complex structure, high misjudgment rate, low detection accuracy, limited applicability and the like in the existing mode hopping detection technology. The method comprises the following steps: acquiring mapping relation data of a to-be-measured laser, and obtaining working wavelengths and main peak total power corresponding to the working wavelengths; the inherent mode interval of the corresponding wavelength is calculated; judging whether the working wavelengths are the same or not, and if yes, obtaining two optical powers corresponding to mode hopping wavelength points on the two sides of the working wavelengths based on the working wavelengths and the intrinsic mode intervals; respectively calculating difference values between the main peak full power and the two optical powers; judging whether the laser jumps modes or not; if not, calculating the average value of the intrinsic mode intervals of all the corresponding wavelengths; and judging whether the laser jumps modes or not. According to the invention, the problems in the prior art are solved, high-efficiency and high-accuracy laser mode hopping detection is realized, and the rapid detection requirement of a production line is met.

The invention relates to the technical field of tunable semiconductor lasers, and discloses a mode-free hopping wavelength tuning method, device and equipment for a tunable laser, and the method comprises the steps: carrying out the scanning of a reflection region current of the tunable laser based on a preset scanning strategy, and obtaining a plurality of ladder data; extracting effective ladder data, and dividing the data belonging to the same wavelength tuning region into one group; for each effective data set, performing midpoint fitting on the effective ladder data, obtaining a smooth wavelength tuning path, and then performing scanning verification and screening feature points; phase current positive and negative loading is carried out at each feature point, a phase region tuning curve is obtained, and a target wavelength is retrieved; and in each smooth wavelength tuning path, splicing all target wavelengths end to end, obtaining an initial current tuning curve, obtaining a target current tuning curve by using an interpolation method, constructing a current tuning curve in a full wavelength range, and taking the current tuning curve as a wavelength current lookup table, thereby realizing the mode-free hopping wavelength tuning method of the tunable laser.

Mode hop detection is provided. A device includes circuitry to receive, from a reader element an indication of one or more properties of a magnetic medium detected by the reader element. The device includes circuitry to determine an envelope of the signal. The device includes circuitry to adjust, responsive to the envelope, a current provided to a laser configured to heat the magnetic medium.

Example systems, data storage devices, and methods for using a harmonic sensor in the read channel of a data storage device to determine phase error are described. The data storage device includes a storage medium with data tracks and a head that can be positioned for reading and writing those tracks. A tone pattern may be written to a data track and a read signal from the tone pattern may subsequently be processed through the harmonic sensor to acquire amplitude data corresponding differences between a target frequency of the tone pattern and a read frequency from the read signal. The amplitude data may be processed to determine phase error values that correspond to an operating condition during writing, such as mode hops and / or down track thermal gradients related to operation of a laser during heat assisted magnetic recording.

The invention relates to a multi-path high-stability narrow-linewidth external cavity semiconductor laser and application thereof, and belongs to the technical field of lasers. The laser comprises two groups of external cavity light paths, Z-block beam combiners, partial reflectors and isolators, the two groups of external cavity light paths are arranged side by side, and the Z-block beam combiners, the partial reflectors and the isolators are sequentially arranged on the light emitting sides of the two groups of external cavity light paths; the external cavity optical path comprises a gain chip, a collimating lens, a polarization analyzer A, a polarization beam splitter, an F-P etalon and a narrow-band-pass filter which are sequentially arranged along the optical path. The polarization analyzer and the polarization beam splitter are arranged in the external cavity light path, main polarized light is kept to resonate in the external cavity light path, the polarization suppression ratio of the external cavity light path is improved, non-dominant mode noise is suppressed, and the line width is reduced; the mode jump risk is reduced, the device life is prolonged, and the power stability is improved; the beam quality is improved; and the polarization dependent loss in a light path is reduced.

The invention discloses a tunable laser mode hopping and fluctuation detection method based on an F-P etalon, mainly relates to the technical field of fiber bragg grating sensing, and is used for mode hopping and fluctuation detection and repair. The method comprises the following steps: firstly, building a fiber grating demodulation system based on F-P etalon, determining the free spectral range FSR and fineness F of a single F-P etalon according to the demodulation precision of the system, calculating the peak width W of the F-P etalon and the number M of the F-P etalon, then carrying out a prior experiment on light path channels corresponding to the M F-P etalon, and finally, carrying out a prior experiment on the M F-P etalon. And calculating optical signal reference data and optical signal measurement data of the optical path of the F-P etalon, carrying out mode hopping and power fluctuation judgment and correction on the tunable laser based on the optical signal reference data and the optical signal measurement data of the optical path of the F-P etalon, and carrying out Bragg grating central wavelength demodulation by the fiber grating demodulation system based on the corrected data.

The invention discloses a laser device mode hopping detection method, and relates to the technical field of laser detection. Comprising the following steps: a to-be-tested laser emits an optical signal, and the optical signal of the laser is converted into an electric signal; and analyzing the frequency spectrum of the electric signal, and determining whether the laser generates mode hopping or not by judging whether a cross relaxation signal caused by double longitudinal modes exists in the frequency spectrum or not. The laser mode hopping detection method provided by the invention is simple in structure, can realize mode hopping real-time monitoring only through the photoelectric detector and the spectrum analyzer, and is low in cost and convenient to deploy; an interferometer or a delay fiber is not needed in the detection process, the anti-interference capability is high, and mode hopping is visually judged through frequency spectrum changes.

The invention relates to the technical field of laser mode hopping detection, in particular to an external cavity laser startup mode hopping detection and correction method, which comprises the following steps: a test stage: in the production test process of a laser, recording power values and temperatures corresponding to different wavelengths of the laser as standard power values W and standard temperatures T, and generating a corresponding table; in the using stage, the laser is adjusted to the standard temperature T corresponding to the expected wavelength, the current power of the laser is detected, the current power is compared with the standard power value W of the expected wavelength in the corresponding table, whether the current power is within the standard power range of the expected wavelength or not is judged, if yes, normal operation is conducted, and if not, mode hopping is judged, and the automatic correction stage is entered; in the automatic correction stage, the power and the temperature of the laser are adjusted to the standard power value W and the standard temperature T range corresponding to the needed wavelength, correction is completed, the production link that the laser must be screened with the help of a special instrument is omitted, and the production efficiency is improved.

A data storage device includes a laser diode that heats an area of a disk near the read / write head. To mitigate mode hopping, the laser diode is preheated using the laser diode itself, such as by applying a reverse bias to the laser diode, during an interruption in writing of data to the disk. The laser diode is preheated to a temperature that maintains operation of the laser diode within a middle portion of a preselected gain mode and away from abrupt shifts in gain modes.

The present invention relates to the technical field of tunable semiconductor lasers and discloses a mode-hopping wavelength tuning method, device and equipment for a tunable laser. The method comprises the following steps: scanning a reflection region current of a tunable laser based on a preset scanning strategy to obtain a plurality of step data; extracting valid step data and dividing data belonging to the same wavelength tuning region into a group; fitting the midpoints of each valid data set to obtain a smooth wavelength tuning path, scanning and verifying, and screening characteristic points; performing positive and negative phase current loading at each characteristic point to obtain a phase region tuning curve and retrieve a target wavelength; and in each smooth wavelength tuning path, splicing all target wavelengths end to end to obtain an initial current tuning curve, obtaining a target current tuning curve by using an interpolation method, constructing a current tuning curve over a full wavelength range as a wavelength current lookup table, and implementing a mode-hopping wavelength tuning method for a tunable laser.

The present invention provides a laser radar device that can detect mode hopping even when the signal contains noise, and can control the laser light source to restore its shifted vertical mode after mode hopping occurs. [Solution] The FMCW type laser radar device 1 comprises a laser light source 2, an optical interference unit 61 that splits and propagates the laser light from the laser light source 2 into two, and an IQ signal generation unit 62 that outputs a beat signal via the optical interference unit 61. In the laser radar device 1, an instantaneous phase calculation unit 64 calculates the instantaneous phase of the beat signal, a mode hop determination unit 65 detects discontinuities in the instantaneous phase, and determines whether or not a mode hop has occurred in the laser light source 2 based on the detection result. If the laser radar device 1 determines that a mode hop has occurred, the light source control unit 7 performs feedback control of the oscillation mode of the laser light source 2 so that the change in instantaneous phase before and after the determination of the occurrence of a mode hop is less than or equal to a predetermined value.

This specification relates to an optical particle counter, a method for using an optical particle counter, and a method for reducing particle counting errors during use of an optical particle counter. The method includes placing an optical isolator between a laser and a flow cell to allow laser light to pass through the flow cell and to reduce the intensity of light returned to the laser as optical feedback that could cause mode hopping.

The embodiment of the invention relates to a surface emitting laser and a light emitting unit. The surface emitting laser includes: a substrate; the bottom reflector structure, the active layer and the top reflector structure are arranged on the substrate; the at least two surface grating units are formed on the surface of the top reflecting mirror structure and located in a lasing area of the surface emitting laser, and each surface grating unit is configured to enable the polarization selection mode of at least one surface grating unit to be different from the polarization selection modes of the other surface grating units. According to the scheme, emission and polarization control of non-fundamental mode laser can be restrained in a targeted mode, selective single / multi-mode stable output is achieved, and the mode hopping phenomenon is reduced.

To provide an optical integrated laser element capable of reducing the occurrence of a mode hop while increasing the intensity of an output laser beam.SOLUTION: The optical integrated laser element includes a distributed feedback laser part, a semiconductor optical amplification part, and a high reflection film. The distributed feedback laser portion includes a diffraction grating and a first optical waveguide. The first optical waveguide is provided along the diffraction grating and has a gain. The semiconductor optical amplifier unit is provided on the substrate, is provided on a first side of the distributed-feedback laser unit, is optically connected to the first optical waveguide, has a gain, and includes a second optical waveguide having a width wider than a width of the first optical waveguide. The high reflection film is provided on an end surface on a second side opposite to the first side of the distributed feedback laser portion. The distributed feedback laser portion and the semiconductor optical amplification portion are integrated on the substrate. The length of the first optical waveguide in the optical waveguide direction is 1000 μm or less, and the length of the second optical waveguide in the optical waveguide direction is 1.5 times or more and 7 times or less the length of the first optical waveguide in the optical waveguide direction.SELECTED DRAWING: Figure 1

The invention discloses a semiconductor laser linewidth compression system based on hybrid optical feedback. The semiconductor laser linewidth compression system comprises a semiconductor laser, an optical fiber beam splitter, a micro-ring resonant cavity, an optical fiber ring resonator and the like. The self-injection locking compression line width is realized through the optical fiber ring resonator, the frequency of the micro-ring resonant cavity is stabilized through backward Rayleigh scattering, and the temperature of the micro-ring is controlled by the temperature sensor and the semiconductor cooler. The system does not need an external complex feedback system, and is compact in structure and low in cost. The mode hopping phenomenon is effectively inhibited, stable narrow linewidth laser output is realized, the linewidth of the laser is remarkably reduced, and the frequency stability is improved. The system is suitable for the fields of optical communication, optical detection and the like, and has the advantages of high stability and low cost.

The invention discloses a metasurface grating waveguide based on a silicon carbide substrate and an enhanced display system, and belongs to the technical field of optoelectronic device manufacturing, and the key points of the technical scheme are that the metasurface grating waveguide comprises a tunable light source, a spatial light modulator, a metasurface grating waveguide, an imaging device and a processing device, modulating the phase distribution of the light to obtain a light beam carrying image information; the processing device is used for adjusting the wavelength of light emitted by the tunable light source and the length of an optical resonant cavity according to the current temperature, and the optical resonant cavity is located in the tunable light source; the metasurface grating waveguide comprises a silicon carbide substrate and is used for conducting a light beam emitted by the focusing lens to the pupil expander so that the pupil expander can output image information to human eyes, the length of the outer cavity is adjusted firstly so that the longitudinal mode frequency can be aligned with the gain peak corresponding to the target wavelength, then the current is adjusted so that the wavelength can reach the target wavelength, and therefore image information can be obtained. The problem of uneven final imaging brightness can be solved while mode hopping is avoided.

The invention provides a ridge waveguide, a high-performance CW laser epitaxial structure and a preparation method thereof, and belongs to the field of semiconductors. The ridge width range Wm of the main waveguide 101 is controlled to be 5-10 [mu] m, the ridge width range Wp of the passive waveguide 102 is controlled to be 1.5-5 [mu] m, a conical coupling area with a 0.8 [mu] m gap is constructed, single-mode output (the side mode suppression ratio is larger than 45 dB) under 500 mA injection current is achieved through mode selection resonance (Q value is larger than 1 * 10 < 4 >), and the power saturation threshold value is increased to 520 mA and is increased by 44% compared with a traditional single ridge waveguide (360 mA). The ridge waveguide provided by the invention also overcomes the defect of mode jump caused by insufficient gap control precision (+ / -0.1 mu m) of the existing double-ridge waveguide.

The invention provides a tunable laser operation mode stability test system and method, and the system consists of a tunable laser, a wavelength recognition module, a photoelectric conversion module, and an acquisition and display module. The stability of the operation mode of the tunable laser is tested by calculating whether the preset discrete electric pulse number is equal to the collected discrete electric pulse number and calculating the proportion of the wavelength trigger difference in the preset interval, the measurement difficulty is remarkably reduced, the problem that instrument performance evaluation is complex is solved, and compared with a conventional standard deviation method, the method has the advantage that the accuracy is high. The measurement precision is improved, the data acquisition amount and the data processing amount in the test process are greatly reduced, and the mode hopping and triggering precision characteristics of the instrument can be reflected more visually and accurately.

The invention relates to a narrow linewidth laser tuning range screening method and device, and belongs to the technical field of optical fiber communication. The method comprises the following steps: step 1, linearly adjusting the temperature of a narrow linewidth laser, and synchronously collecting wavelength and optical power data; step 2, when mode hopping of the optical power is detected, recording temperature-wavelength-power data before and after mode hopping and resetting; step 3, refining temperature stepping in a mode hopping temperature interval by adopting a successive approximation method, and positioning a maximum tuning wavelength value; 4, comparing the actually measured tuning range with a preset threshold value, and outputting a judgment result whether the tuning range is qualified or not; the device comprises a processor module, a current control circuit, a temperature control circuit, an optical power detection circuit and a wavelength detection module, a complete screening device is constructed, the current control module, the temperature control module, the optical power detection module, the wavelength detection module and the processing module are integrated, a closed loop from the method to hardware is achieved, full-automatic screening is supported, and the screening operability is improved.

The present invention discloses an optoelectronic signal transmission method for an optical and electrical hybrid cable, which relates to the field of optoelectronic signal transmission and includes: continuously monitoring the modal distribution of the optical signal in the optical fiber, identifying and recording the jump phenomenon of the optical signal from single mode to multi-mode through a modal analysis algorithm; real-time monitoring the change characteristics of the electric field strength during the transmission of the electrical signal, and analyzing the possibility of the electric field inducing the mode jump of the optical signal based on the optical signal state at the time of the modal jump and the electric field data at that moment; based on the prediction result of the jump data model, automatically calling the built-in optical signal compensation algorithm to respond in the early stage when the signal undergoes a mode jump, and maintaining the single-mode or specific multi-mode transmission state of the optical signal; when the compensation adjustment fails, automatically performing transmission mode switching to adjust the propagation mode of the optical signal, and on the basis of the prediction model, adopting an optical signal modulation compensation algorithm to adjust the transmission state of the optical signal at the initial stage of the jump, and reducing the influence of mode switching.

A solution for detecting laser mode shifts in hard disk drives can include a first circuit that provides a signal with a step voltage whose amplitude is adjustable according to a first control signal. The solution can include a second circuit that delays the signal by a time period to generate a delayed signal, with the time period also adjustable according to a second control signal. The solution can include a filter that receives the delayed signal as input and provides an offset signal as output, corresponding to the frequency response of a sensor. The system can subtract the offset signal from a sensor signal to provide an output.

The present invention provides an external cavity laser tuning device and method. A gain chip, a collimating lens, a wedge lens, and a diffraction grating are sequentially installed along an optical axis. The rotation pivot point of the diffraction grating is located at the intersection of the optical axis and the diffraction surface of the diffraction grating. The device has a simple structure. The cavity length is tuned by longitudinally translating the wedge lens installed between the collimating lens and the diffraction grating. At the same time, the rotation pivot point is located at the center of the diffraction grating. Rotating the diffraction grating only affects frequency selection but not longitudinal modes. This greatly reduces the effects of mechanical structure instability and thermal sensitivity on the cavity length during rotation, thereby improving the stability of wavelength tuning and optimizing wavelength tuning without mode hopping over a large range.

This description relates to optical particle counters, methods of using optical particle counters, and methods of reducing particle count errors during use of an optical particle counter. The method includes placing an optical isolator between the laser and the flow cell to allow laser light to pass into the flow cell, and to reduce the intensity of light re-directed back into the laser as optical feedback capable of causing mode hopping.

One solution concept can detect a mode-shifting HDD laser mode change within an improved response time by using a sensor amplification circuit that is balanced by the frequency response of a gain stage circuit. A sensor in a first circuit can receive an optical signal from a laser as input and output a first voltage, which an amplifier can then amplify to produce a boosted first voltage that indicates a mode-shifting event lagging the optical signal by a first response time of the first frequency response.A second circuit, connected in series with the first circuit and operating according to a second frequency response that is an inverse of the first frequency response, can receive the amplified first voltage and, at least on the basis of the amplified first voltage set by the second frequency response, generate a second voltage that indicates the mode-hopping event within a second response time that is shorter than the first response time.

This application belongs to the field of quantum precision measurement technology, and specifically discloses an external cavity semiconductor laser frequency stabilization system and a frequency stabilization method. The system includes a saturated absorption spectrum module, a wavelet peak seeking module, a modulation and demodulation module, a bias amplification module, and a switch module. The saturated absorption spectrum module outputs an electrical signal of the saturated absorption spectrum. Under the control of a frequency locking instruction, the wavelet peak seeking module outputs a target bias voltage signal corresponding to the locked frequency based on the electrical signal. The modulation and demodulation module performs signal modulation and demodulation based on the electrical signal and a reference signal corresponding to the locked frequency, and outputs a modulation signal and a demodulation signal. The bias amplification module superimposes and amplifies the modulation signal, the demodulation signal, and the target bias voltage signal, and outputs a target superimposed signal to the PZT modulation port of the laser, so that the output laser operates freely at the locked frequency. Through this application, the laser is not prone to mode hopping during the frequency locking process, making the entire frequency stabilization system more stable, and having a simple structure and low cost.