190 results about "Threshold current" patented technology

The invention relates to the technical field of semiconductor lasers, in particular to a laser based on a bimetallic Bragg grating and a top surface HR reflecting film, which comprises a gain chip, a first high-reflection HR film is plated on the left end surface of the gain chip, and a first anti-reflection AR film is plated on the right end surface of the gain chip. A metal Bragg grating waveguide is arranged on the right side of the gain chip, the right end face of the gain chip and the left end face of the metal Bragg grating waveguide are aligned and attached to form an outer cavity structure, and the left end face of the metal Bragg grating waveguide is plated with a second anti-reflection AR film. The right end face of the metal Bragg grating waveguide is plated with a third anti-reflection AR film. Performance test is carried out on the laser provided by the invention, and test results show that the line width is 0.6 kHz, the SMSR is 63dB, and the threshold current is 22mA, thereby verifying the effectiveness of the laser provided by the invention.

The invention relates to the technical field of semiconductor lasers, in particular to a temperature regulation and control device and method for a semiconductor laser, and the method comprises the steps: obtaining different types of monitoring curves, and analyzing the complex change characteristics of operation temperature and operation power according to the monitoring curves, so as to determine a heat accumulation effect index; determining the degree of efficiency loss caused by the heat accumulation effect by analyzing the correlation among the operation temperature change, the operation power change and the threshold current change and combining the heat accumulation effect index; then determining a temperature regulation and control demand coefficient by analyzing the temperature feedback control precision condition and the thermal dynamic characteristic of the semiconductor laser and combining the efficiency loss degree; and finally, a default proportional gain value in the PID control module is adjusted by using the temperature regulation and control demand coefficient to obtain an adjusted proportional gain value so as to carry out temperature regulation and control on the semiconductor laser, which is beneficial for the temperature regulation and control device to respond to the change of the working environment of the laser in time.

The invention relates to the technical field of semiconductor lasers, in particular to a laser based on a bimetallic Bragg grating and a top SiO2 waveguide layer, which comprises a gain chip, the left end face of the gain chip is plated with a first high-reflection HR film, and the right end face of the gain chip is plated with a first anti-reflection AR film; a metal Bragg grating waveguide is arranged on the right side of the gain chip, the right end face of the gain chip and the left end face of the metal Bragg grating waveguide are aligned and attached to form an outer cavity structure, and the left end face of the metal Bragg grating waveguide is plated with a second anti-reflection AR film. The right end face of the metal Bragg grating waveguide is plated with a third anti-reflection AR film. According to the invention, a temperature change test is carried out, and the wavelength drift is controlled to be + / -0.002 nm in a range of-40 DEG C to 85 DEG C; performance test results show that the line width is 0.6 kHz, the SMSR is 65 dB, and the threshold current is 22 mA.

The invention provides a multi-wavelength frequency comb laser working point screening method. The method comprises the following steps: S1, setting a starting current, a current interval, a termination current, a starting voltage, a voltage interval and a termination voltage according to threshold current performance parameters and use requirements of a to-be-screened multi-wavelength frequency comb laser; and S2, according to the initial current, the current interval, the termination current, the initial voltage, the voltage interval and the termination voltage set in the step S1, controlling a current source and a voltage source to output current and voltage to the multi-wavelength frequency comb laser to be screened for multiple times according to the current interval and the voltage interval, acquiring output spectral information of the multi-wavelength frequency comb laser under each current and voltage condition by adopting a spectrograph; s3, automatically analyzing the number of the optical frequency combs in each piece of spectral information through a computer by adopting a preset spectral analysis method, and summarizing the numbers of the optical frequency combs of all the spectral information to make a working point diagram; and S4, current and voltage corresponding to the point with the maximum number of optical frequency combs in the working point diagram are selected as working points.

Disclosed is a semiconductor laser, from bottom to top, comprising: a substrate, a lower limiting layer, a lower waveguide layer, an active layer, an upper waveguide layer, and an upper limiting layer. The lower limiting layer is composed of at least one of AllnGaN, AllnN, AlGaN, InN, AlN, InGaN, and GaN. A thickness of the lower limiting layer is denoted as x, and 10 angstroms≤x≤90,000 angstroms. The lower limiting layer includes a first lower limiting layer, a second lower limiting layer, and a third lower limiting layer. The lower limiting layer forms an electron saving structure and a stress regulating structure to regulate a carrier distribution and a stress distribution of the active layer, thereby reducing a threshold current and improving a slope efficiency of the laser.

A pixel circuit includes: a phototransistor configured to receive, by one region of a source and a drain, inflow of photo-carriers generated by light entering a substrate, and configured to output a voltage signal from the one region; and a blocking layer provided on another region of the drain and the source and on a side of a channel far from a surface, and configured to prevent the photo-carriers from directly flowing into the other region. The phototransistor causes a sub-threshold current to flow between the source and the drain in a pinch-off state. Each of the source and the drain of the phototransistor is periodically reset to a reset voltage. The reset voltage is set to a voltage between a voltage at which a dark current of the phototransistor becomes zero and a voltage at which a bias voltage of the phototransistor becomes zero.

The invention relates to the technical field of aging test, and discloses a laser chip accelerated aging test method, which comprises the following steps: synchronously measuring the optical power, the threshold current, the slope efficiency and the emergent wavelength of a laser chip in an accelerated aging environment to obtain a time sequence data matrix; performing double sparse dictionary decomposition on the time series data matrix to obtain a normal feature coefficient and a degradation feature coefficient; calculating a target characteristic value of the time-varying covariance matrix based on the degradation characteristic coefficient, and generating a dynamic characteristic value sequence and a corresponding degradation stage identifier according to the target characteristic value; and based on the degradation stage identifier, inputting the dynamic characteristic value sequence into a life prediction model for life prediction, and obtaining the remaining service life. The method can accurately capture the nonlinear characteristic and the time evolution mode of the laser chip degradation process, automatically identify the time period characteristic which contributes to life prediction, and improve the service life of the laser chip. And the accelerated aging test accuracy of the laser chip is improved.

The invention provides a quantum well laser epitaxial structure and a quantum well laser. The epitaxial structure comprises a substrate, a buffer layer, a lower cladding, a lower waveguide layer, a quantum well active region, an upper waveguide layer, an upper cladding and a contact layer which are stacked in sequence, wherein the lower cladding is used for limiting laser leakage in a first direction, and the upper cladding is used for limiting laser leakage in a second direction; the band gap width of the lower waveguide layer is between the lower cladding and the quantum well active region, the band gap width of the lower waveguide layer is greater than the band gap width of the quantum well active region, and the refractive index of the lower waveguide layer is greater than the refractive index of the lower cladding; the quantum well active region comprises one or more quantum well layers and chirp barriers, the quantum well layers and the chirp barriers are arranged in an overlapped mode, and the chirp barriers are used for reflecting electrons and holes so as to limit the electrons and the holes to compositely emit light in the quantum well layers. According to the epitaxial structure disclosed by the invention, the interaction of electron holes is enhanced, the optical gain can be improved, the threshold current of the device is reduced, and the characteristic temperature is improved.

The invention relates to the technical field of semiconductor lasers, in particular to a laser based on a bimetallic Bragg grating and a top surface HR reflecting film, which comprises a gain chip, a first high-reflection HR film is plated on the left end surface of the gain chip, and a first anti-reflection AR film is plated on the right end surface of the gain chip. A metal Bragg grating waveguide is arranged on the right side of the gain chip, an annular resonance optical waveguide is arranged on the front side of the ridge optical waveguide, the right end face of the gain chip and the left end face of the metal Bragg grating waveguide are aligned and attached to form an outer cavity structure, and the left end face of the metal Bragg grating waveguide is plated with a second anti-reflection AR film. The right end face of the metal Bragg grating waveguide is plated with a third anti-reflection AR film. Performance test is carried out on the laser provided by the invention, and test results show that the line width is 0.6 kHz, the SMSR is 63dB, and the threshold current is 22mA, thereby verifying the effectiveness of the laser provided by the invention.

The invention provides a red laser based on a perovskite structure and a preparation method thereof, and belongs to the field of semiconductor quantum dot lasers. The red light laser sequentially comprises a reflecting layer, a P-surface electrode, a hole transport layer, a perovskite active layer, an electron transport layer and an N-surface electrode from bottom to top, the reflecting layer is formed by alternately stacking HfO2 layers and SiO2 layers; the hole transport layer is formed by doping a scandium element into nickel oxide; and the perovskite active layer is a CsPbBr12 / PbSe heterojunction layer. According to the laser, the carrier transmission efficiency of the perovskite quantum dots in the active area is improved, and the output power and efficiency of the red laser are improved; an F-P cavity mode is used as a resonant cavity, and the output power of a laser beam is improved by increasing oscillation in a working medium. The red light laser has the advantages of being simple in structure, simple in preparation method, good in heat dissipation, high in luminous efficiency, high in photoluminescence intensity, low in threshold current, high in output power and the like.

The invention provides a direct current system pure light CT measurement method and system under fast transient large current and a simulation method, and the method comprises the steps: setting a threshold current Ith, the interval time N of a sample during differential operation, and the time Tdown for keeping in a large current algorithm as preset values; and a condition that a measurement error is generated when a fast transient large current is encountered is avoided by utilizing reasonable setting of a parameter N in a pure light CT (Computed Tomography) demodulation algorithm. Different demodulation algorithms (an Arctan demodulation method of small current and a di / dt integral demodulation method of large current) are selected according to the magnitude of the current, so that the rapid transient large current can be measured more accurately. According to the method, the measurement defects of a traditional pure light CT are overcome, accurate data measurement under rapid transient large current can be achieved, current state quantities of various devices under similar lightning stroke working conditions can be reproduced and analyzed, and the method has remarkable practical value.

The invention relates to a quantum cascade laser with a cylindrical waveguide and a preparation method thereof, and belongs to the field of photoelectron, the quantum cascade laser comprises a laminated structure, the laminated structure is provided with two waveguide grooves, a ridge waveguide is formed between the two waveguide grooves, the waveguide grooves are hyperbolic, and the ridge waveguide is cylindrical; the bottom and side wall areas of the waveguide groove are subjected to mechanochemical grinding treatment and filled with InP: Fe, then mechanochemical grinding is carried out again, and then an insulating film layer material is evaporated; due to the unique cylindrical shape of the ridge waveguide, the photon density can be effectively improved, and the output characteristic of laser is optimized; and meanwhile, the mode distribution of light can be better controlled, and excellent laser characteristics are realized by utilizing optical reflection and interference effects. According to the invention, before secondary epitaxy, a mechanochemical grinding method is adopted to carry out surface treatment on the double channels, so that waveguide loss after secondary epitaxy of InP: Fe can be effectively reduced, the threshold current density is further reduced, and the output power and the slope efficiency are increased.

A diagnostic circuit includes a superconducting quantum interference device (SQUID) configured to be coupled to a test circuit such that an electronic noise present in the test circuit induces a first current that flows through the SQUID. The diagnostic circuit also includes a current path configured to receive a second current that flows through the SQUID. The SQUID is configured to generate an output in a form of: a first voltage in response to a sum of the first current and the second current being less than a threshold current and a second voltage in response to the sum of the first current and the second current being greater than the threshold current.

The invention relates to a GaN-based micro-disk laser with a diamond nano-composite current barrier layer. The laser comprises a substrate layer and a lower contact layer which are sequentially arranged along the epitaxial growth direction of a chip, the middle of the upper surface of the lower contact layer is a lower cladding; a lower waveguide layer, a quantum well active layer and an upper waveguide layer are sequentially arranged at the upper part of the lower cladding; the electron blocking layer is of an annular structure and is distributed on the outer side of the upper surface of the upper waveguide layer. The electron blocking layer is sequentially covered with an upper cladding layer and an upper contact layer; a central region between the upper surface of the upper waveguide layer and the upper surface of the upper contact layer is filled with a nano composite current blocking layer and overflows out of the upper surface of the upper contact layer; rectangular array nano columns are arranged in the nano composite current blocking layer. Through the good heat dissipation performance of the diamond nanorod structure, the service life of the device is prolonged, the expansion of current to the central area is effectively relieved, and the threshold current of the device is reduced.

The invention relates to the technical field of semiconductors, and discloses a GaAs-based vertical-cavity surface-emitting laser with a small-size mesa structure and a preparation method thereof.The laser comprises an n-surface electrode layer, a substrate layer, a buffer layer and an n-DBR layer which are sequentially arranged from bottom to top, and an insulating layer located on the periphery is arranged above the n-DBR layer; a lower space layer, a quantum well active region, an upper space layer, a p-oxidation limiting structure layer, a p-DBR layer, a contact layer and a p-surface electrode layer which form a cylindrical mesa are sequentially arranged at the center of the insulating layer from bottom to top; the p-oxidation limiting structure layer comprises a low-refractive-index layer, an oxidation limiting layer and a high-refractive-index layer which are sequentially arranged from bottom to top, an aluminum oxide layer is formed on the periphery of the oxidation limiting layer through an oxidation process, an oxidation hole is formed in an unoxidized area in the center of the oxidation limiting layer, and the difference between the diameter of the cylindrical table board and the diameter of the oxidation hole is smaller than or equal to 15 microns. According to the invention, the threshold current can be reduced and the luminous power can be improved.

A diagnostic circuit includes a superconducting quantum interference device (SQUID) configured to be coupled to a test circuit such that an electronic noise present in the test circuit induces a first current that flows through the SQUID. The diagnostic circuit also includes a current path configured to receive a second current that flows through the SQUID. The SQUID is configured to generate an output in a form of: a first voltage in response to a sum of the first current and the second current being less than a threshold current and a second voltage in response to the sum of the first current and the second current being greater than the threshold current.

The invention relates to a quantum cascade laser with a heterogeneous waveguide and a preparation method of the quantum cascade laser, and belongs to the technical field of photoelectronics. The stacked structure comprises an N-type InP substrate, an N-type InP buffer layer, an N-type InP lower waveguide layer, an N-type GaInAs lower limiting layer, a multi-period active region structure, an N-type GaInAs upper limiting layer, an N-type InP upper waveguide layer and an N-type highly-doped InP ohmic contact layer from bottom to top; a part of the N-type highly-doped InP ohmic contact layer is reserved above the N-type InP upper waveguide layer, and a VO2 deposition layer is arranged above the rest of the N-type highly-doped InP ohmic contact layer; an upper electrode metal layer is deposited above the thin film layer and the N-type highly-doped InP ohmic contact layer; and a lower electrode metal layer is arranged below the N-type InP substrate. By regulating and controlling the optical limiting factor and the waveguide transmission loss factor, the output power of the chip is improved, and the threshold current density is reduced.

The present invention discloses a method for preparing a ridge waveguide analog laser with a low threshold current. The method comprises the following steps: cleaning the substrate with an organic solvent to remove surface contaminants and oxides; introducing nitrogen gas into a dry and clean reactor; placing the substrate on a carrier plate in the reactor, and heating the reactor to the growth temperature; introducing source gases into the reactor using a flow controller to control the flow rates of various source gases; and automatically controlling the film thickness via the reactor. After growth is complete, the reactor temperature is gradually lowered. After cooling, all substrates and observation films are removed. High-resolution X-ray diffraction and photoluminescence measurements are performed to confirm that the tensile strain of the quantum wells grown in the crystals is consistent with the design, thereby ensuring the crystal quality and device performance of the epitaxial wafer. The present invention can reduce the threshold current of the laser by 50% under the same conditions. The unique quantum well design achieves high gain and narrow linewidth, making it valuable for widespread application.

An all-epitaxial, electrically injected surface-emitting green laser operates in a range of about 520-560 nanometers (nm). At 523 nm, for example, the device exhibits a threshold current density of approximately 0.4 kilo-amperes per square centimeter (kA / cm2), which is over one order of magnitude lower than that of previously reported blue laser diodes.

In various embodiments, a computer-implemented method includes determining a size of a display area of a display panel on which one or more images are being displayed, determining a threshold current value based on the size, measuring a first current drawn by the display panel, determining whether the first current exceeds the threshold current value, and upon determining that the first current exceeds the threshold current value, causing a second current providing power to a light source associated with the display panel to be shut off.

The embodiment of the application provides a test method, network equipment and an optical module, relates to the technical field of optical communication, and improves the influence caused by the failure problem of the optical module. The specific scheme is as follows: the network equipment obtains threshold currents of the optical module at different time points in sequence, whenever a threshold current is obtained, the network equipment obtains the aging rate at the current time point based on the obtained threshold current and the aging rate at the previous time point, and the network equipment obtains the life margin of the optical module at the current time point based on the initial threshold current, the obtained threshold current and the aging rate at the current time point, wherein the initial threshold current is obtained according to the temperature at the initial time point of the current test of the optical module and a mapping relationship. The embodiment of the application is used for the process of predicting the life margin of the optical module by the network equipment.

The present invention proposes a fitting method for the ultra-low reflectivity of optical coatings to solve the technical problem of large measurement errors in the ultra-low reflectivity of optical coatings. The steps of the present invention are as follows: simulating and calculating the effective refractive index of the waveguide of an uncoated FP laser chip at both ends to obtain the reflectivity of the uncoated FP laser chip and air; performing a P-I test on the uncoated FP laser chip at both ends to obtain a threshold current; performing an ultra-low optical coating on one end of the uncoated FP laser chip to obtain a laser chip with one end coated; applying different current values ​​to the laser chip with one end coated according to the threshold current and testing the corresponding spectral curves; using the spectral curves under different current values, the reflectivity of the ultra-low optical coating is obtained according to the reflectivity fitting. The present invention can accurately estimate the ultra-low reflectivity of the optical coating, playing a decisive role in the optimization of SLD and SOA products.

This invention relates to a dual-comb control system for a terahertz quantum cascade laser, comprising a first terahertz quantum cascade laser, a second terahertz quantum cascade laser, a first T-type biaser, and a second T-type biaser. The first terahertz quantum cascade laser operates in optical frequency comb mode, while the second terahertz quantum cascade laser operates above a threshold current. The first and second terahertz quantum cascade lasers emit terahertz light from each other. The first terahertz quantum cascade laser also functions as a detector to detect a mixing signal. The state of the mixing signal is switched by changing the power of the radio frequency signal generated by the radio frequency source. This invention enables the switching of the mixing signal between chaotic, unstable, and dual-comb states under high drive current, significantly improving the spectral width and application scenarios of the dual-comb system based on the quantum cascade laser.

The invention belongs to the technical field of control circuits, and particularly relates to a threshold current control circuit for a PSI5 interface. According to the circuit, the positive input end of an operational amplifier is connected with the drain electrode of an NMOS tube M1 and one end of a resistor R2, the negative input end of the operational amplifier is connected with one end of a resistor R1, and the output end of the operational amplifier is connected with the grid electrode of the NMOS tube M1; the source electrode of the NMOS tube M1 is connected with the drain electrode of the NMOS tube M2, the grid electrode of the NMOS tube M2 and one end of the resistor R4, and the source electrode of the NMOS tube M2 is grounded; the other end of the resistor R4 is connected with one end of a capacitor C1 and a grid electrode of the NMOS tube M3, and the other end of the capacitor C1 is grounded; the drain electrode of the NMOS tube M3 is connected with one end of the resistor R3, and the source electrode of the NMOS tube M3 is grounded; the other ends of the resistors R1, R2 and R3 are connected with a power supply; according to the invention, the threshold current control of the PSI5 interface is realized without depending on the feedback control of a digital circuit.

The invention relates to a method, implemented by a control system for an electrical converter, for controlling said converter, comprising the following steps: a step (40) of determining the peak-to-peak amplitude of the current in a low-frequency switching branch of the converter; a step (42) of comparing the peak-to-peak amplitude to a threshold current value; if the peak-to-peak amplitude is greater than or equal to the threshold current value, a step (44) of deactivating the switching branch; otherwise, a step (46) of determining whether a mathematical relationship is verified; if the verification is negative, corresponding to a discontinuous diode conduction mode, a step (48) of keeping the switching branch active; otherwise, a step (50) of keeping the switching branch active or deactivating it according to a predefined criterion. Abstract figure: Fig. 2

The application discloses a nano-ampere current source with process voltage temperature compensation capability and a design method, comprising a current bias circuit and an adaptive constant current bias voltage generating circuit; the current bias circuit is used for realizing nano-ampere sub-threshold current bias; the bias voltage generating circuit is used for extracting the characteristics of a target circuit under different processes, power supply voltages and temperature conditions, so as to obtain a corresponding bias voltage variation characteristic curve and guide the construction of the current bias circuit. The nano-ampere current source with process voltage temperature compensation capability can not only provide accurate current bias for a sub-threshold circuit, but also has the ability to resist process, power supply voltage and temperature fluctuations, and can avoid the use of large-size current mirror MOS tubes, thereby saving the layout area.

According to the gallium nitride-based semiconductor laser with the gradually-changed polarized optical phonon energy waveguide layer, a fitting curve of In ion strength distribution or In atom concentration distribution of an upper waveguide layer and a lower waveguide layer is tested through SIMS, and a fitting curve of polarized optical phonon energy distribution meets any function distribution of Log3P1, Lop2P2 and Biphase. The spatial continuous regulation and control of the phonon energy of the optical field are realized, so that the LO phonon energy is continuously and gradually changed along the propagation direction, the phonon energy gradient is formed, the LO phonon scattering is improved, the inelastic scattering and energy relaxation of carriers and LO phonons are inhibited, the carrier transportation and phonon scattering are optimized, the service life of the carriers and the gain retention time are prolonged, and the optical field performance is improved. According to the invention, the threshold current density is reduced, the thermal stability of the laser is improved, the use power and the use temperature of the laser are improved, meanwhile, the phonon energy valley value is matched with the quantum well gain peak, the scattering loss is inhibited, additional scattering caused by phonon energy mutation is avoided, the light field limitation is enhanced, and the slope efficiency is improved.

The invention relates to the technical field of semiconductor lasers. The number of quantum wells of the strained quantum well active region structure is limited by strain accumulation, the total thickness needs to be smaller than the critical thickness, implementation is achieved by increasing the number of the quantum wells, but the excessive number of the quantum wells can cause increase of threshold current; according to the high-speed multi-junction cascaded wafer fusion type vertical cavity surface emitting laser and the preparation method thereof, the active regions are connected in series in the same resonant cavity by using the tunnel junctions, so that the threshold carrier density is effectively reduced, the differential gain of the laser is improved, the threshold current is reduced, and the performance of the laser is improved. And the output power and the small signal modulation bandwidth of the laser are remarkably improved while the resistance and the absorption loss are not multiplied.

A laser display system 100 is configured to increase the dynamic range of a laser diode by modulating an operating current applied to the laser diode based on a desired sequence of brightness levels and a temperature of the laser diode. In some embodiments, a measuring circuit measures a voltage of the laser diode at a given current, which indirectly indicates the temperature of the laser diode, thus obviating the need for a direct measurement of temperature. In addition, in some embodiments, the measuring circuit identifies a threshold current of the laser diode based on a range of current values at which values of the current multiplied by the derivative of the voltage against the current vary relatively rapidly. By compensating for temperature effects and identifying the threshold current, a driver of the laser diode more precisely controls light output of the laser diode across an increased dynamic range.