131results about How to "Lower threshold current" patented technology

The invention discloses a vertical-cavity surface-emitting laser which comprises a substrate, a first Bragg reflector, a first limiting layer, an active region, a second limiting layer, a second Bragg reflector and an Ohmic contact layer which are arranged in a laminated manner, wherein the active region adopts a quantum well structure, a potential barrier layer is made of InGaAlAs, and a potential well layer is made of InGaAsN; a heavily-doped tunnel junction and a third limiting layer are also arranged between the second limiting layer and the second Bragg reflector; an oxidized limiting layer is also arranged in the second limiting layer. The invention also provides a preparation method of the laser. The laser has the advantages that the laser uses an InGaAsN / InGaAlAs material system as the active region, has large conduction band order ratio and can effectively limit injected carriers, so that the threshold current is reduced, and the laser gain is improved; on an isometric wavelength band of 1550 nm, the content of N required by an active region material is lower, and devices with high material quality are easy to obtain.

Provided is a load circuit protection device, which discriminates an inrush current, which is generated when a semiconductor switch or a switch provided in the downstream of the semiconductor switch is turned on, and an excess current generated in a load from each other, and protects a load circuit by turning off the semiconductor switch only when the excess current is generated. A detection current (I1) detected by an ammeter (15) and a preset threshold current (Iref) are compared with each other by means of a comparator (CMP1), and in the case where the detection current (I1) reaches the threshold current (Iref), the semiconductor switch (11) is turned off and the load circuit is protected. Furthermore, a voltage (Vd) in a cable connecting a battery (VB) and the semiconductor switch (11) is measured, and in the case where a counter-electromotive force is generated and the voltage (Vd) is reduced, the threshold current (Iref) is reduced. Therefore, when a dead short-circuit is generated, the detection current (I1) quickly reaches the threshold current (Iref) and turns off the semiconductor switch (11), and when the inrush current is generated, since the detection current (I1) does not reach the threshold current, erroneous interruption is prevented from being generated.

A semiconductor light emitting device of the present invention comprises a n-type InP substrate (1), and a stripe structure (10) formed in the stripe shape on the n-type InP substrate (1) and comprised of a n-type InP lower cladding layer (3), an active layer (4) having a resonator in a direction parallel to the n-type InP substrate (1), and a p-type InP upper cladding layer (5). The stripe structure (10) has a photonic crystal structure (2) with concave portions 9 arranged in rectangular lattice shape, and the direction in which the concave portions (9) of the photonic crystal structure (2) are arranged corresponds with a resonator direction. A stripe-shaped upper electrode (6) is formed on the stripe structure (10) to extend in the resonator direction. The semiconductor light emitting device of the present invention so structured is configured to radiate light in the direction perpendicular to the n-type InP substrate (1).

The invention relates to an n-type ZnO and p-type GaN combined ZnO-base vertical cavity surface emitting laser and a manufacturing method thereof, and belongs to the technical field of semiconductor light emitting devices and manufacturing methods thereof. The laser consists of a substrate 1, a p-type GaN epitaxial layer 2, a current lower limitation layer 3 and a lower electrode 5 which are prepared on the epitaxial layer 2 and independent of each other, an n-type ZnO-base material light emitting layer 4 prepared on the current lower limitation layer 3, an upper electrode 6 and the like, andis characterized in that: a multi-layer AlGaN / GaN thin film distributed bragg reflector (DBR) lower reflector 8 is grown and prepared between the substrate 1 and the p-type GaN epitaxial layer 2; an n-type broadband gap ZnO-base ternary system material current upper limitation layer 7 is prepared on the n-type ZnO-base material light emitting layer 4; and the upper electrode 6 and a multi-layer medium thin film DBR upper reflector 9 which are independent of each other are prepared on the current upper limitation layer 7. The n-type ZnO and p-type GaN combined ZnO-base vertical cavity surface emitting laser has the advantages that: due to a controllable resonant cavity, the output power of the device can be enhanced; the direction of laser becomes better; and the application range of the device is expanded.

The integrated device one semiconductor laser and wedged waveguide mode spot converter includes substrate area, light guiding area, limiting arean and electrode area. The limiting arean on the substrate includes one n-type lower limiting layer of doped InP; one p-type upper limiting layer of doped InP, which includes two layers, one layer on the light guiding arean and the other layer below the electrode area; one p-type layer of un-oxidized InAlAs stripes and Al-containing oxide stripes arranged alternately between two p-type upper limiting layers; and one optical medium film on two ends of the device. The electrode arean is made on the limiting arean and below the substrate area. The Al-containing oxide layer limits the injected current and laser field in the semiconductor laser part and makes the lower light guiding area form wedged waveguide in the wedged waveguide mode spot converter part.

The invention discloses a GaN-based semiconductor device and a manufacturing method thereof. The GaN-based semiconductor device comprises a silicon substrate and an epitaxial layer formed on the silicon substrate, and is characterized in that the epitaxial layer comprises an AlN nucleating layer, an AlGaN buffer layer and a GaN buffer layer which are sequentially formed on the silicon substrate. According to the invention, a dielectric film is adopted to act as a mask layer, different effects are achieved through regulating and controlling the periodicity of a dielectric layer, and the dielectric layer can act as a limiting layer when the periodicity reaches the maximum, so that the optical loss can be effectively reduced, and threshold current of a laser and a super-radiation light-emitting diode is reduced; and the electric layer acts as an interface layer when the periodicity is small and forms another optical waveguide structure together with AlGaN at the bottom, a planar coupling optical waveguide laser and a super-radiation light-emitting diode are formed, and a nearly-circular light spot with a good shape can be acquired.

A traditional vertical cavity surface emission semiconductor laser is in a completely symmetric round shape, output light of the laser is round symmetric light beams, the light beams are not hollow and is in an instable polarization state. The invention provides a semiconductor laser with an elliptic annular window. The structure is shown as figures: the elliptic annular window 1, an upper electrode 2, an ohmic contact layer 3, an upper distributed Bragg reflection mirror 4, an oxide limitation layer 5, a semiconductor material active gain layer 6, a lower distributed Bragg reflection mirror 7, a substrate 8 and a lower electrode 9, the overall structure from the elliptic annular window to the active gain layer is an elliptic cylindrical structure, the ratio selection range between the length of a long shaft and the length of a short shaft of the elliptic structure is 3:2 to 5:4, a central region of the elliptic cylindrical structure is hollow, and an elliptic etching region 10 formed by etching is etched from the ohmic contact layer to the upper distributed Bragg reflection mirror. The semiconductor laser works in an electric pumping mode, elliptic hollow light beams can be emitted under the effect of the elliptic annular window, the emitted elliptic hollow light beams have favorable polarization characteristics, and the polarization is in a stable state.

A total-reflection optical waveguide semiconductor laser chip and a manufacturing method thereof are disclosed. The semiconductor laser chip comprises an epitaxial wafer. The epitaxial wafer comprisesa substrate, a lower cladding, an active area, an upper cladding and an Ohmic contact layer which are successively arranged from bottom to top. The center position of the epitaxial wafer is providedwith a ridge-type optical cavity. The two sides of the ridge-type optical cavity are provided with isolation grooves. The outer side of each isolation groove is provided with a shoulder area. The upper surface of the epitaxial wafer is provided with a high-reflectivity optical film layer and a P electrode layer. The manufacturing method comprises the following steps of (1) forming the epitaxial wafer; (2) carrying out one-time photoetching; (3) evaporating a high-reflectivity optical film; (4) carrying out two times of photoetching; (5) carrying out three times of photoetching; (6) manufacturing the P electrode layer; (7) carrying out substrate thinning; (8) manufacturing an N electrode layer; (9) carrying out strip dissociation and coating; and (10) forming a single laser chip. In the invention, the optical limiting of an optical cavity is realized, the threshold current of the laser chip is reduced, photoelectric conversion efficiency is increased, an output light shape is obviouslyimproved, stray light is eliminated and chip reliability is increased.

The invention discloses a preparation process of a ridge-type waveguide DFB laser based on a double-glue-layer structure. Windowing of a ridge-type region current channelcomprises the steps: depositing a SiO2 insulating layer in a plasma enhanced chemical vapor deposition mode; coating a first layer of photoresist on the surface of the SiO2 insulating layer, and baking the first layer of photoresist to prevent the first layer of photoresist from being corroded by a wet method; coating a second layer of photoresist on the first layer of photoresist; baking the second layer of photoresist, wherein the baking temperature and time are both lower than those of the first layer of photoresist; performing exposure and development on the second layer of photoresist by using the photomask; corrodingthe second layer of photoresist subjected to exposure and development by adopting a wet etching process; etching the first layer of photoresist by adopting an RIE dry etching process; and etching theSiO2 insulating layer by adopting an RIE dry etching process, and removing the SiO2 insulating layer on the ridge strips to form a current channel. According to the method, the ridge-shaped structurewith a complete vertical shape on the side surface can be prepared.

The invention discloses a surface emitting laser which comprises a substrate and a functional layer which is of a sandwich-like type structure. The functional layer comprises a first doped layer, an active layer, a limiting layer and a second doped layer, wherein the active layer and the limiting layer are positioned between the first doped layer and the second doped layer. The first doped layer and the second doped layer are used for conveying carriers to the active layer, and the carriers can firstly pass through the limiting layer and then be transmitted to the active layer to compositely emit light. The limiting layer comprises an insulation layer and a conductive column and the conductive column runs through the insulation layer according to a thickness direction, and thus, the carriers need to be transmitted to the active layer through the conductive column, an area of a carrier compounding region of the active region can be limited, and in a case of keeping the same carrier density, a required injection current is smaller, so that in the premise of not changing a volume and an area of photon crystals, a threshold current required for photon excitation is reduced. The invention further provides a surface emitting laser array which also has the beneficial effects above.

The invention discloses a long wavelength GaNAsBi / GaAs multiple-quantum well laser, comprising a lower limit layer, a lower wave guide layer, an active region, an upper wave guide layer, an upper limit layer and an ohmic contact layer, which are connected in sequence, wherein the active region adopts a GaNAsBi / GaAs multiple-quantum well structure. According to the invention, the threshold current of the laser can be lowered, the gain of the laser can be increased, the refrigeration-free work can be realized, the laser is suitable for multiple lasers such as a surface launching laser, the production cost of the laser is far lower than that of an INP (indium phosphide)-based laser, no Al exists in the active region of the multiple-quantum well laser, the growth technics difficulty can be reduced, and the yield of the laser can be increased and the service life of the laser can be prolonged.

The invention relates to the technical field of laser, and discloses a laser radar device. The laser radar device comprises a signal transmitting module, a signal receiving module, an optical path adjusting module and a data processing module, wherein the signal transmitting module is used for transmitting a laser signal to a target object; the signal receiving module is integrated with the signaltransmitting module on the same laser radar main board, and is used for receiving the laser signal reflected by the target object; the optical path adjusting module is arranged on an optical path inwhich the laser signal locates, and is used for adjusting the optical path of laser; and the data processing module is connected with the signal receiving module, and is used for analyzing and processing the laser signal reflected by the target object. The signal transmitting module is a vertical cavity surface emitting laser (VCSEL) array. The signal transmitting module and the signal receiving module are integrated on the same laser radar main board, thereby greatly simplifying the structure of the laser radar device, reducing the size of the existing laser radar device, improving the integration degree, and conforming to the trend of miniaturization of the current laser radar.