17 results about "Mode hopping" patented technology

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.

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 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 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.

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 device and control method provide mode-hopping-free laser wavelength (frequency) tuning over a wide frequency band of the gain bandwidth of the gain medium, and possibly the entire gain bandwidth of the gain medium. In general, the apparatus and method include reverse dispersion to compensate for wavelength dependent group delay and group velocity dispersion within the laser cavity to achieve broadband mode hopping free wavelength tuning.

The application provides a tunable laser mode hopping suppression system and method and a tunable laser, and relates to the technical field of precision optics, and comprises a power detection module, a displacement detection module and a cooperative compensation module.The power detection module is used for separating sample light of a predetermined proportion from laser output light, and determining laser output power based on the sample light.The displacement detection module is used for measuring an actual driving displacement amount of a micro driver.The cooperative compensation module is used for determining whether mode hopping occurs according to a first derivative of the laser output power and a driving voltage of the micro driver, calculating a deviation amount between a theoretical displacement driving amount corresponding to a current injection voltage of the micro driver and the actual driving displacement amount when it is determined that mode hopping occurs, determining compensation coefficients of injection current compensation and injection voltage compensation according to the deviation amount, and adjusting an injection current of a laser diode and an excitation voltage of the micro driver according to the compensation coefficients of the injection current compensation and the injection voltage compensation.The application realizes mode hopping detection and suppression when the laser works.

The invention relates to the technical field of light spot detection, and particularly discloses a computer vision-based laser light spot quality intelligent detection method, which comprises the following steps of: establishing a causal decoupling graph neural network, modeling multiple physical degeneration sources of a laser, successfully decomposing mixed wavefront distortion into independent physical degeneration elements, according to the method, source tracing of the root cause of laser quality reduction is achieved, meanwhile, the multi-scale wavelet packet energy entropy analysis and the time sequence convolution network are adopted in parallel, the energy instability characteristics of the light spots are extracted, accurate prediction of the short-term failure probability of the light spots is achieved, and the accuracy of the prediction result is improved. Therefore, the defects that in the prior art, early warning cannot be obtained before disastrous failures such as mode jump or energy collapse of light spots are about to occur, finally, wrong and passive monitoring runs through the whole machining batch and is found until expensive workpiece scrapping or system shutdown maintenance is caused, and serious economic losses and time waste are caused are overcome.

This invention discloses a semiconductor laser linewidth compression system based on hybrid optical feedback, comprising a semiconductor laser, an optical fiber beam splitter, a micro-ring resonator, and an optical fiber ring resonator. The optical fiber ring resonator achieves self-injection locking linewidth compression, while the micro-ring resonator achieves frequency stabilization through backscattering Rayleigh scattering. A temperature sensor and a thermoelectric cooler control the micro-ring temperature. This system eliminates the need for a complex external feedback system, resulting in a compact structure and low cost. This invention effectively suppresses mode hopping, achieves stable narrow-linewidth laser output, significantly reduces laser linewidth, and improves frequency stability. This system is suitable for applications such as optical communication and optical detection, offering advantages of high stability and low cost.

The application provides a ridge waveguide, a high-performance CW laser epitaxial structure and a preparation method thereof, and belongs to the field of semiconductors. m The ridge width range W of the passive waveguide 102 is controlled to be 5-10 μm p The ridge width range W of the passive waveguide 102 is controlled to be 1.5-5 μm 4 A tapered coupling area with a gap of 0.8 μm is constructed, single-mode output (side mode suppression ratio > 45 dB) is realized under 500 mA injection current through mode selection resonance (Q value > 1 x 10 The power saturation threshold is improved to 520 mA, which is increased by 44% compared with a traditional single-ridge waveguide (360 mA). The ridge waveguide of the application also breaks through the mode jump defect caused by insufficient gap control precision (±0.1 μm) of the existing double-ridge waveguide.

The invention discloses a self-injection locking laser based on mode jump suppression of a jump structure and a working method of the self-injection locking laser, and belongs to the field of laser technologies and optoelectronic devices. The single longitudinal mode laser output by the DFB passes through the C4, the CIR and the ISO and then enters the No.1 port of the C1; light waves input from the first port of the C1 are circularly propagated along a defined initial path, an input reflective path, a jump connection path, an output reflective path and a transmission path, and light waves under the multi-path interference effect are output from the first port of the C2; after passing through a No.1 output port of the C3, the VOA, the CIR and the C4, the signal is automatically injected back to the DFB; the light wave passing through a No.2 output port of the C3 is connected to an oscilloscope through a PD, so as to monitor the mode state of the self-injection locking laser; and a No.1 output port of the C4 detects the performance of the locked laser. The mode hopping phenomenon in the optical fiber annular resonant cavity can be effectively restrained, and line width narrowing and frequency stabilization of the laser are achieved.

The invention provides a method for compensating and calibrating wavelength and power of an external cavity semiconductor laser module, which comprises the following steps of: searching a mode hopping point under working current, and calibrating a central point of a single-mode interval corresponding to the mode hopping point to be the optimal working temperature; measuring the output power of the laser as calibration power, and measuring the wavelength of the laser as calibration wavelength; setting an environment temperature in the environment temperature interval, respectively carrying out temperature tuning and current tuning to reach the calibration power and the calibration wavelength, and recording the laser shell temperature and the measured digital laser temperature and digital working current; circulating the process; performing polynomial fitting on the digital laser temperature and the digital working current by taking the laser shell temperature as an independent variable; and calculating the current digital laser temperature and digital working current according to the current laser shell temperature. According to the invention, single-mode stable laser output in a wide environment temperature range is realized; and the stability of power and wavelength is realized, and the cost is low.