43 results about "Mode hopping" patented technology

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 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.

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 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 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 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 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.

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 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.

The present description relates to optical particle counters, methods of using optical particle counters, and methods of reducing particle count errors during use of optical particle counters. The method includes placing an optical isolator between a laser and a flow-through tank to allow laser light to travel into the flow-through tank and to reduce the intensity of light redirected back into the laser as optical feedback capable of causing mode hopping.

The invention provides an optical integrated laser element capable of improving the intensity of output laser light and reducing the generation of mode hopping. The optical integrated laser element includes a distributed feedback laser section, a semiconductor light amplification section, and a highly reflective film. The distributed feedback type laser part is arranged on the InP substrate and is provided with a first optical waveguide. The first optical waveguide is an active area of laser. The semiconductor optical amplification unit is provided on the InP substrate and has a second optical waveguide optically connected to the first optical waveguide and having a width wider than that of the first optical waveguide. The second optical waveguide is an active area of the amplifier. The highly reflective film is provided on an end surface of the distributed feedback laser section on the side opposite to an end surface on the semiconductor light amplification section side. The reflectance of the highly reflective film is 70% or more. The length of the first optical waveguide is 1000 [mu] m or less, and the length of the second optical waveguide is 1.5-7 times the length of the first optical waveguide.

The application discloses a super surface 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 technical scheme is characterized by comprising a tunable light source, a spatial light modulator, a super surface grating waveguide, an imaging device and a processing device, the spatial light modulator is used for receiving light emitted by the tunable light source, modulating the phase distribution of the light, and obtaining a light beam carrying image information; the processing device is used for adjusting the wavelength of the light emitted by the tunable light source and the length of an optical resonant cavity according to the current temperature, the optical resonant cavity is located in the tunable light source; the super surface grating waveguide comprises a silicon carbide substrate and is used for conducting the light beam emitted by a focusing lens to a pupil expander, so that the pupil expander outputs image information to a human eye, and the application can avoid mode jumping and solve the problem of uneven final imaging brightness by adjusting the length of an external cavity first, aligning the gain peak corresponding to the target wavelength of the longitudinal mode frequency, and then adjusting the current to make the wavelength reach the target wavelength.

The utility model provides a semiconductor laser coupling single-mode fiber system, which comprises a semiconductor laser, a front lens group, a pinhole diaphragm, a rear lens group and a single-mode fiber which are sequentially arranged along a light path, the middle part of the pinhole diaphragm is provided with a pinhole, light beams emitted by the semiconductor laser are focused to the pinhole by the front lens group, and the light beams emitted by the rear lens group are focused to the single-mode fiber by the rear lens group. And the light beam enters the rear lens group through the small hole, and is focused to the end face of the single-mode optical fiber by the rear lens group. According to the semiconductor laser coupling single-mode optical fiber system, a lens structure is combined with small hole filtering, so that the optical coupling efficiency is ensured, stray light reflected to the semiconductor laser by specular reflection light and diffuse reflection light is reduced, and optical noise caused by mode jump is reduced.

The application provides a large-range continuously tunable external cavity semiconductor laser without mode hopping, which comprises a laser diode (1), a collimating lens (2), a polarization beam splitter (3), a narrow-band interference plate (4), a prism super high reflectivity film (5) and a piezoelectric module (6) arranged in sequence in an optical path, and the rotating axis of the prism super high reflectivity film (5) is located in the optical path of the laser and coincides with the rear surface of the piezoelectric module (6). The large-range continuously tunable external cavity semiconductor laser without mode hopping of the application utilizes the sensitivity of laser frequency to the rotation angle of the narrow-band interference plate, changes the interference plate angle and the cavity length at the same time, thereby realizing the high synchronization of the change of the interference plate transmission peak center frequency and the specific cavity mode frequency with the angle, realizing the laser with the laser output frequency without mode hopping and the continuous tunable output frequency with the rotation angle of the cavity mirror.

The invention discloses a DFB laser device mode hopping processing method, a control device and a heating device, and relates to the technical field of DFB laser devices, the DFB laser device is provided with a heating resistor, and the method comprises the following steps: applying a voltage signal to the heating resistor to heat the heating resistor; and adjusting a voltage signal applied to the heating resistor to enable the temperature of the DFB laser to be within a preset temperature range. The DFB laser is heated to the preset temperature range through the heating resistor, so that the mode hopping risk of the DFB laser is reduced.

The invention is entitled "VCSEL array for HAMR." The present disclosure relates to the pre-processing of a magnetic recording head for a magnetic media drive. For a heat-assisted magnetic recording (HAMR) head, an optical source provides the heat necessary for the drive operation. A vertical cavity surface emitting laser (VCSEL) is mounted to the top surface of the slider. A plurality of laser beams are emitted from the bottom surface of the VCSEL and are directed to a corresponding number of waveguide structures within the HAMR head. The waveguide structures feed into a multimode interference (MMI) device which then directs the laser light into a single waveguide to be focused on a near-field transducer (NFT). The VCSEL laser is phase coherent and does not have mode hopping.

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.

[Problem] To provide an optical measurement device capable of improving deterioration of measurement accuracy caused by mode hop. [Solution] An optical measurement device according to an embodiment of the present disclosure comprises: a wavelength sweeping light source that emits light of a wavelength corresponding to a supply current; at least one delay interferometer that has a plurality of light-guiding waveguides that have different lengths; and an analyzer that, based on a phase difference between a plurality of beat signals obtained by photoelectrically converting the output light of the delay interferometer guided to the plurality of waveguides, identifies a mode hop interval where a mode hop in which the wavelength changes discontinuously is generated.

The invention discloses a single longitudinal mode continuous tuning optical fiber ring cavity laser based on dispersion compensation. The single longitudinal mode continuous tuning optical fiber ring cavity laser comprises a pumping source, a beam combiner, a gain optical fiber, an isolator, a saturable absorber, a wavelength adjustable filtering device, a dispersion compensation device, a circulator, a total reflective mirror and a beam splitter. The pumping source is coupled into the gain optical fiber through the beam combiner to provide gain for a laser signal; the isolator is arranged behind the gain optical fiber and used for guaranteeing one-way transmission of laser in the ring cavity and restraining return interference. The gain light passing through the isolator realizes continuous tuning control of the central wavelength through the wavelength adjustable filter device, then sequentially passes through the beam splitter, the circulator and the dispersion compensation device, and finally returns to the beam combiner to form a closed loop, so that a stable optical fiber ring cavity is constructed. The beam splitter outputs part of the light as a laser signal, while the main optical path continues to maintain intracavity oscillation. The mode hopping phenomenon in the frequency sweeping process can be effectively restrained, and it is guaranteed that the laser keeps single-longitudinal-mode continuous output within the whole tuning range.

A laser assembly includes a vertical cavity surface emitting laser and a resonant cavity extension. The resonant cavity extension is defined by two separate portions. A first portion may be formed from gallium arsenide and can define a microlens. A silicon dioxide layer can be disposed over the first portion and may be polished to a flat, planar surface. Reflective layers may interpose the first portion and second portion of the resonant cavity extension, and a reflective layer may be disposed over the planar surface. As a result of this construction, an extended cavity vertical surface emitting laser can be defined that is resistant to mode hopping and exhibits improved coherence length, beam divergence (high numerical aperture), and beam quality.

A laser module includes a gain chip, temperature sensors, a case, and a thermoelectric cooler (TEC). The gain chip emits a laser beam. One of the temperature sensors measures a first temperature of the gain chip and is encompassed by the gain chip. The other temperature sensor is adhered to the case and measures a second temperature. The TEC tunes the laser beam emitted by the gain chip to a desired wavelength by varying the first temperature of the gain chip through a set of third temperatures for various values of the second temperature. The set of third temperatures is selected from various values of the first temperature such that the laser beam emitted at the set of third temperatures is mode-hop free.