64 results about "Internal resonance" patented technology

The invention relates to a flexible mechanical arm energy consumption shock absorption device based on 2:1 internal resonance, and the shock absorption device consists of a shock absorber installation seat, a torsion spring, a connecting turntable, an inertia adjusting ball, a swinging supporting rod and an adjustable damper, wherein the shock absorber installation seat is connected with a flexible mechanical arm through a screw, the adjustable damper is connected with the shock absorber installation seat through a bolt, the connecting turntable is tightened onto a rotating shaft of the adjustable damper, the torsion spring penetrates the rotating shaft of the adjustable damper, two ends of the torsion spring are respectively connected with the adjustable damper and the connecting turntable, the swinging supporting rod is connected with the connecting turntable in a threading way, and the inertia adjusting ball penetrates the swinging supporting rod via a through hole and is fixedly connected with the swinging supporting rod through a tightening screw; and a flexible mechanical arm energy consumption shock absorption method based on the 2:1 internal resonance comprises twelve steps. The flexible mechanical arm energy consumption shock absorption method and the device can be used for the vibration control of an aerospace flexible arm mechanism, a microelectronic manufacturing flexible arm, robot system flexible mechanical hand and the like and have characteristics of obvious shock absorption effect, simplicity in structure and good robustness.

The object of the invention is a method for charging a rechargeable battery having non-liquid electrolyte, which battery has an internal resonance frequency. The charging process contains at least one charging interval performed with current pulses, the frequency of said current pulses is essentially identical with the internal resonance frequency of the battery to be charged. Following the charging interval consists of periodic current pulses optionally a second relaxation interval is inserted, in which no charging current is applied to the rechargeable battery, within which optionally a second discharging interval is applied. After the second relaxation interval the charging is performed in an interval consists of a continuous charging current, whereafter an optional first relaxation interval is inserted, within which optionally a second discharging interval is applied. This sequence of the above steps can be varied and applied repeatedly until the full charge of the battery is attained.

The invention discloses a solving method used for dynamic response when an elastic boundary shallow arch generates internal resonance. The method is carried out on the basis of a dimensionless kinetic equation, corresponding rigidity parameters are used for representing the magnitudes of vertical elastic constraint and rotating-direction elastic constraint on the shallow arch, the modality of the elastic boundary shallow arch is supposed through a general solution and a particular solution to a differentiation equation, the natural vibration frequency is obtained due to the fact that a determinant corresponding to a modality coefficient matrix is equal to zero, an average equation in the polar form under the three internal resonance conditions of 1:2, 1:1 and 1:3 is derived through Galerkin discretization of the kinetic equation of the shallow arch and multiscale perturbation analysis, and therefore dynamic response used when the internal resonance is generated can be obtained. Due to the thought that constraint rigidity is considered in the modality and the natural vibration frequency, existing technical problems generated in a dynamic response solving process when the elastic boundary shallow arch generates the internal resonance are solved. Safety and reasonability of the built shallow arch are guaranteed, and the service life of the shallow arch can be prolonged.

A system for transient over voltage protection of a three-phase transformer. Two surge arresters are series connected across each winding of the transformer and the center point connection of the two surge arresters is electrically connected to a middle location of the winding. Three additional surge arresters are electrically connected from each phase to ground in the case of either a delta or Y connected transformer; and / or connected from a neutral point to ground in the case of a Y connected transformer. The system allows for all of the surge arresters to be packaged as an integrated surge arrester system to minimize induced transient over voltages and high stresses on the transformer winding due to internal resonances.

A two-stage screw compressor of the invention includes a low pressure stage casing provided with a low pressure stage compression mechanism, a discharge casing provided on a discharge side of the low pressure stage casing, a high pressure stage casing provided with a high pressure stage compression mechanism, and intermediate stage casings for connecting the discharge casing and the high pressure stage casing, and accommodating an electric motor. In such a two-stage screw compressor, a cavity is formed on a discharge casing side in the slide valve so as to enlarge the capacity of a discharge space formed in the discharge casing. Thereby, internal resonance occurring in the discharge casing is prevented.

The invention discloses a deep-sea platform mooring system parametric excitation-internal resonance coupled vibration analysis and control method. The method comprises the following steps of: (1) performing static analysis on a platform and a cable, and determining the inherent vibration property of the platform; (2) analyzing the influence of different wave heights and wave frequencies on the kinetic properties of the platform and a mooring coupling system by using the calculation result of the static analysis as a condition of kinetic analysis, and calculating the change of parametric excitation-internal resonance coupled motion amplitude of the platform through time; and (3) adjusting a ballast system of a hard bin and a soft bin in a parametric excitation-internal resonance coupled motion state, and changing the gravity center position and the buoyancy center position of a platform main body to adjust the inherent frequency ratio of heaving oscillation to pitching oscillation so that the pitching oscillation of the platform main body is inhibited. By using the method, the parametric excitation-internal resonance motion of the platform is controlled by changing the gravity center position and the buoyancy center position of the platform and destroying the dynamical conditions for producing parametric excitation-internal resonance under the condition of possibly unstable parametric excitation-internal resonance motion.

The invention discloses a testing method and a testing system for nonlinear internal resonance representation of fiber composite boards. The method includes selecting internal resonance inherent frequencies of two steps of a composite board, and pre-determining dimension parameters and material parameters, for forming internal resonance of the composite board, according to an integral-multiple coordination method; processing the composite board; testing the internal resonance inherent frequencies of the two steps of the composite board; judging whether the internal resonance inherent frequencies of the two steps are in integral-multiple relation or not, and if not, adjusting the clamping position of the composite plate slightly and retesting the internal resonance inherent frequencies of the two steps of the composite board to enable the internal resonance inherent frequencies of the two steps to have integral-multiple relation; performing internal resonance representation testing on the composite board under different stimulation conditions, analyzing vibration characteristics of nonlinear internal resonance, and concluding change rules of nonlinear vibration response. By the testing method, an integral-multiple coordination theory is provided to calculate the inherent frequency of the composite board, specific parameters of the composite board are determined, and accordingly,testing accuracy and efficiency are high.

The object of the invention is a method for charging a rechargeable battery having non-liquid electrolyte, which battery has an internal resonance frequency. The charging process contains at least one charging interval performed with current pulses, the frequency of said current pulses is essentially identical with the internal resonance frequency of the battery to be charged. Following the charging interval consists of periodic current pulses optionally a second relaxation interval is inserted, in which no charging current is applied to the rechargeable battery, within which optionally a second discharging interval is applied. After the second relaxation interval the charging is performed in an interval consists of a continuous charging current, whereafter an optional first relaxation interval is inserted, within which optionally a second discharging interval is applied. This sequence of the above steps can be varied and applied repeatedly until the full charge of the battery is attained.

The invention relates to a biomedical wireless energy transmission system. Through adopting a magnetic coupling resonant wireless energy transmission technology, a transmission distance demand of general biomedical implanted equipment is satisfied, wherein in the technology, a farthest transmission distance can reach a meter-level range; a reconfigurable rectifier is realized to work under three working modes of a half-wave rectifier, a full-wave rectifier and a voltage multiplier, and duty ratios of the different working modes are controlled so that transmission efficiency can be guaranteed and simultaneously output power of an internal receiving circuit is adjustable; and different input capacitances of the rectifier under the different working modes can cause a detuning problem of an internal resonance circuit, therefore, a resonance adjusting unit is introduced so that internal and external resonance circuits are at a same resonant frequency, and transmission efficiency is increased. In addition, through a voltage regulation device and an overvoltage protection circuit, a supply voltage of the biomedical implanted equipment is safe and stable.

The invention relates to a fiber composite thin plate nonlinear vibration characterization test method based on vibration measurement with laser, First, the inherent frequency and modal shape of a fiber composite thin plate needs to be obtained accurately. Then, a nonlinear vibration characterization test is carried out according to a test idea of from a time domain to a frequency domain and thento a time-frequency domain. The specific steps are as follows: testing inherent frequency of each order of the fiber composite thin plate; testing the modal shape of each order of the fiber compositethin plate according to the inherent frequency; carrying out a harmonic distortion nonlinear characterization test; carrying out a nonlinear time-varying damping characterization test; carrying out ahard / soft rigidity nonlinear characterization test; carrying out a characterization test of amplitude dependent on nonlinear damping; carrying out a nonlinear jump characterization test; carrying outan ultraharmonic / subharmonic resonance nonlinear characterization test; and carrying out an internal resonance nonlinear characterization test. The method provided by the invention can obtain variousnonlinear vibration characterization of the fiber composite thin plate through one-time testing, a test result is relatively accurate, the test efficiency is improved, and an important reference is provided for establishing a method system for a nonlinear vibration test of a composite structure of this type.

The invention discloses a nonlinear dynamic vibration absorption and electromagnetic energy dissipation device. The device comprises a box-shaped structure, a shape memory alloy spring, a shape memory alloy stranded wire, a mass block and two magnets; the top and the bottom of an outer box are each fixedly provided with one magnet to form a uniform magnetic field, the upper end of the spring is connected with the bottom of one magnet, the lower end of the spring is connected with the mass block, the stranded wire is inserted into the middle of the spring in a penetrating mode, and the mass block can swing in multiple directions; the spring and the mass block form a spring pendulum, the motion mode of the spring pendulum adopts a coupling mode of a spring vibration mode and an overall swinging mode, when internal resonance conditions are met, the phenomenon that one kind of vibration motivates the other kind of vibration can occur, and therefore the effect of nonlinear vibration absorption can be achieved. The swing frequency of the spring is in consistent with the main vibration frequency of a controlled structure, strong coupling of the vibration mode and the swinging mode of the spring pendulum is achieved, the internal resonance characteristics are achieved, and the optimal vibration absorption and reduction effect is achieved.

The invention relates to a vibration control method based on internal resonance, which is oriented to the longitudinal torsional vibration of an engine, and belongs to the technical field of vibration control of a vehicle engine. The vibration control method comprises the following steps of: establishing a six-degree-of-freedom vibration equation of the engine; constructing a control model of a vibration absorber; establishing a seven-degree-of-freedom vibration equation of the engine with the vibration absorber; decoupling the seven-degree-of-freedom vibration equation, and adjusting the frequency of the vibration absorber to be half of the frequency of a controlled mode; and extracting a controlled mode and vibration absorber mode vibration equation, and solving the controlled mode and vibration absorber mode vibration equation by a multi-scale method. According to the vibration control method disclosed by the invention, through the construction of a nonlinear coupling term, the internal resonance is formed, the vibration energy of the engine is transferred to the vibration absorber, and the vibration energy of the engine is dissipated by the damping of the vibration absorber. The vibration control method disclosed by the invention is obvious in vibration reduction effect, simple in structure and low in energy consumption.

A system for transient over voltage protection of a three-phase transformer. Two surge arresters are series connected across each winding of the transformer and the center point connection of the two surge arresters is electrically connected to a middle location of the winding. Three additional surge arresters are electrically connected from each phase to ground in the case of either a delta or Y connected transformer; and / or connected from a neutral point to ground in the case of a Y connected transformer. The system allows for all of the surge arresters to be packaged as an integrated surge arrester system to minimize induced transient over voltages and high stresses on the transformer winding due to internal resonances.

The invention relates to an internal-resonance broadband vibration energy harvester of an L-shaped beam structure. The internal-resonance broadband vibration energy harvester is composed of the L-shaped beam, a piezoceramic wafer, a lower permanent magnet, an upper permanent magnet, a mass block, a lead-out circuit and an insulating base station. The lower end of the vertical beam body of the L-shaped beam is clamped through the insulating base station and connected to a structure needing to achieve vibration energy harvesting through the insulating base station. The piezoceramic wafer is fixed to the outer surface of the position, close to the lower fixed end, of the vertical beam body of the L-shaped beam. The lead-out circuit is connected to the piezoceramic wafer. The lower permanent magnet is fixed to the position, close to the right angle, of the horizontal beam body of the L-shaped beam. The upper magnet which is opposite in polarity with the lower permanent magnet is fixed to the position over the lower permanent magnet by a certain distance. The mass block is fixed to the free end of the horizontal beam body of the L-shaped beam. The energy harvester is portable and simple in structure and easy to implement, thereby being capable of being widely applied in the fields of automobiles, steamers and other machines.

The invention discloses a power transmission tower and power transmission line mode internal resonance analysis system and method. The system comprises a power transmission tower measurement target, a power transmission line measurement target, a power transmission tower binocular recognition monitoring system and a power transmission line binocular recognition system. The method is characterized by, to begin with, arranging targets at specific positions of a power transmission tower and a power transmission line; then, carrying out continuous shooting by utilizing high-speed cameras, and transmitting the pictures to an image processing computer through transmission lines; and through image processing software in the computer, calculating transient variation of displacement of the tower according to change of distance between two adjacent target points, and then, obtaining a transmission tower-transmission line vibration mode. The system has the advantages of good operability and stability and high sampling rate, high accuracy, non-contact and real-time collection and the like, and can realize effective monitoring of tower vibration in real time, thereby providing basis for research of wind-induced collapse of the power transmission tower, and optimizing future structural design.

A power transmission tower vibration damper comprises a cylinder-shaped metal box body fixedly installed in the center of the top of a power transmission tower, a high-damping spring made of a martensite shape memory alloy is suspended in the center of an inner top plate of the metal box body, a solid steel ball is tied at the lower end of the high-damping spring, and elastic adhesive tapes are pasted to the inner side wall of the metal box body. According to the power transmission tower vibration damper, under the effect of external excitation, the high-damping spring of the damper conducts damping by depending on internal resonance of the swing modal and the vibration modal of the high-damping spring and the restoring force of the high-damping spring when the solid steel ball and the box body do not collide; when colliding with the box body under the effect of a dynamic load, the solid steel ball applies work by depending on collision force of the box body to the solid steel ball to conduct damping; and the mass ratio of the solid steel ball to the power transmission tower, the inner diameter and the height of the metal box body and the length and the strength of the high-damping spring are obtained through provided computational formulas, and the power transmission tower vibration damper can achieve the best damping effect.

The invention discloses an active-passive parallel-type vibration absorber based on an internal resonance mechanism. The active-passive parallel-type vibration absorber based on the internal resonancemechanism comprises a vibration absorber body, a control system and a vibration simulating plate. The vibration absorber body comprises a balancing weight, a swinging support rod, a rotation shaft, an upper frame, a lower frame, a servo motor, a flange plate, a torsional spring upper bracket, a torsional spring, and a torsional spring lower bracket. The control system comprises an acceleration sensor, a dynamic signal analyzer, an upper computer, a motion control card, and a driver. According to the active-passive parallel-type vibration absorber, through the parallel design of the torsionalspring and the servo motor, a passive control mode of the torsional spring and a semi-active control mode of the servo motor are successfully parallelly connected and combined. The whole vibration absorber has the characteristics of the semi-active control mode of low energy consumption, good stability, adjustable parameters, and non-linear large amplitude vibration, and also has the characteristics of the passive control mode of simple structure, low cost, and no a large amount of outside energy input. The response is rapid, the application range is extensive, and the vibration reducing effect is apparent.

The invention belongs to the field of switching power sources, and provides a Boost converter. The Boost converter is characterized in that an auxiliary resonance network is additionally arranged on the basis of an existing topological structure, and meanwhile a high-frequency signal and low-frequency signal combined control mode is adopted in a main switching pipe. Internal resonances of the auxiliary resonance network are adopted, at the moment when high-frequency signals are cut off, the voltage across the high-level end and the low-level end of the main switching pipe is increased from zero, and the zero-voltage shutoff of the main switching pipe is accordingly achieved; meanwhile, the voltage across the high-level end and the low-level end of the main switching pipe is decreased to zero at the startup moment or the shutoff period of the high-frequency signals, zero-voltage startup of the main switching pipe is accordingly achieved, and the main switching pipe can work in the high-frequency complete soft switching state or the high-frequency critically-complete soft switching state. In this way, magnetic elements and EMC filters can be small in design size by improving the switching frequency of the main switching pipe, and the size and the weight of the Boost converter are accordingly reduced.

The invention discloses a bistable vortex-induced vibration energy capturing device based on internal resonance. The bistable vortex-induced vibration energy capturing device is composed of a cantilever beam, a piezoelectric plate, a circular section bluff body, a permanent magnet, a spring and a load circuit, wherein the cantilever beam is placed in fluid, vortex-induced vibration generated when the fluid impacts the bluff body is used for promoting the cantilever beam to generate reciprocating vibration, and kinetic energy of the fluid is converted into electric energy by means of the piezoelectric patch. Non-linear restoring force is generated through non-linear magnetic repulsion between the permanent magnets, the device generates bistable vibration, linear elasticity is increased to achieve the internal resonance phenomenon of the energy harvesting device, the internal resonance effect and the bistable vibration mode are combined, and the device is applied to the field of vortex-induced vibration energy harvesting power generation; the vortex-induced vibration energy capturing device is expected to become an effective way for widening the working bandwidth of the vortex-induced vibration energy capturing device and improving power generation efficiency.

The invention relates to a direct-acting magneto-rheological fluid shock absorber with controllable stiffness, which belongs to the technical field of vibration control. The shock absorber includes the controlled object and the magnetorheological fluid shock absorber, wherein the controlled object is the vibration control object, and the magnetorheological fluid shock absorber is composed of a support plate, a slide rail, a slider, a connecting plate, a lock nut, Gasket, piston rod, upper piston, outer sleeve, excitation coil, inner sleeve, damping channel, magnetorheological fluid, lower piston, floating piston, nitrogen chamber and working cylinder. The stiffness of the magnetorheological fluid in the magnetorheological fluid damper can be controlled by changing the current of the excitation coil, so as to meet the internal resonance requirements between the controlled object and the magnetorheological fluid damper in the system. The damping consumes vibration energy to achieve the purpose of vibration reduction. The invention utilizes the internal resonance phenomenon for vibration reduction, has obvious vibration reduction effect, strong robustness and less energy consumption, and has good practical value in the vibration reduction of vehicle engines, flexible mechanical arms and other fields.

The invention discloses an automatic-control valve control circuit. The automatic-control valve control circuit comprises an input zeroing circuit, a voltage comparator circuit, an error amplifier circuit, a gain amplifier circuit, a buffer amplifier circuit, an H bridge drive circuit, a two-stage sampling circuit and a dynamic regulating circuit. According to the automatic-control valve control circuit, based on the original circuit, the dynamic relating circuit, the zeroing circuit and the two-stage speed detecting circuit when an automatic-control valve works are additionally arranged, so that influence of an internal resonance circuit to an input low-frequency square wave signal when the automatic-control valve works is eliminated, dynamic regulating and automatic tracking of the automatic-control valve control circuit are realized, the product precision is improved, the stability when a product normally works is guaranteed, and reliability of integral performances is high.

A vibrator includes a vibrator element and a base on which the vibrator element is installed. In addition, when n is set to a natural number equal to or greater than 2, and j is set to a natural number equal to or greater than 1 and equal to or less than n, the vibrator element includes n inherent vibration modes having resonance frequencies different from each other, and when a resonance frequency of a main vibration of the vibrator element in the n inherent vibration modes is set to ω1 in a relationship between an arbitrary integer kj and a resonance frequency ωj corresponding to each of the n inherent vibration modes, the following three expressions are all satisfied.Δω≡(∑j=2n⁢kj⁢ωj-k1-ω1) / ω1ω1≥0.1⁢⁢3≤∑j=1n⁢⁢kj≤10

The invention relates to an intelligent graphene acupuncture point plaster. The plaster comprises a graphene circuit arranged inside a plaster body and located at the side, towards the human body, of the wearing face of the acupuncture point plaster, an internal resonance unit adopting a wireless receiving mode and a silver paste layer, wherein the resonance unit is connected with a graphene circuit and comprises a radio frequency part, a simulation part and a digital part, the digital part comprises a digital control part and a storage, the silver paste layer coats the outer surface of the graphene circuit, and the graphene circuit uniformly and rapidly absorbs human biologic waves. Due to the corresponding structural configuration, when a user wears the acupuncture point plaster to an acupuncture point where physical therapy is needed, the human biologic radio waves are absorbed by the graphene circuit, then, due to absorption strengthening of the internal resonance unit, absorbed weak radio waves are amplified and transmitted to the human body through the internal resonance unit, and therefore acupuncture points, meridians and collaterals are stimulated; the effect of tending to acupuncture is achieved, and therefore the problems of human blockage of channels and blockage of vigor are solved.

The invention discloses a dual-band transmission type antenna. The dual-band transmission type antenna comprises a dielectric substrate and metal panels. The dielectric substrate is a square plate, the metal panels are circular plates, there are several metal panels and the metal panels are arranged in rows and columns and attached to a front surface and a back surface of the dielectric substrate.Each metal panel is a pattern generated after etching and hollowing, and the pattern is divided into an internal resonance structure, an external resonance structure and a middle isolation circular ring with a circle center as a benchmark. In the invention, each metal panel is used as a basic unit; the plurality of metal panels are arranged in rows and columns and attached to the front surface and the back surface of a dielectric substrate to form the dual-band transmission type antenna. Compared with a traditional single-band transmission type antenna, the dual-band transmission type antennahas advantages that the resonance structure is shaped, independent regulation and control performance on different frequency bands and a dual-band working characteristic are particularly outstanding,the structure is simple, transmission efficiency is high, and manufacturing is convenient.

A two-stage screw compressor of the invention includes a low pressure stage casing provided with a low pressure stage compression mechanism, a discharge casing provided on a discharge side of the low pressure stage casing, a high pressure stage casing provided with a high pressure stage compression mechanism, and intermediate stage casings for connecting the discharge casing and the high pressure stage casing, and accommodating an electric motor. In such a two-stage screw compressor, a cavity is formed on a discharge casing side in the slide valve so as to enlarge the capacity of a discharge space formed in the discharge casing. Thereby, internal resonance occurring in the discharge casing is prevented.

The invention discloses an internal resonance type vibration reduction method suitable for a space large-scale flexible structure. The method comprises the following steps: establishing a vibration control equation of an antenna and a vibration absorber by utilizing a Kane method; introducing a nonlinear coupling feedback item, and constructing a feedback control model of the vibration absorber; solving a nonlinear vibration control equation by utilizing a singular perturbation method; and performing internal resonance analysis and stability analysis on the solution of the vibration equation.According to the invention, a nonlinear internal resonance vibration reduction mechanism is utilized, and a semi-active control mode is adopted, so that the vibration energy of the antenna is transmitted to the vibration absorber and dissipated. By adding the artificially constructed nonlinear feedback coupling item, the control and adjustment performance of the vibration absorber is enhanced, theresponse speed is high, the application range is wide, and the actual vibration reduction effect is obvious.

The invention discloses a wireless-sensor-oriented piezoelectric and electromagnetic combined type power supply device. A base is fixedly connected to the middle of the bottom of a shell, four piezoelectric and electromagnetic combined power supply units are connected between the shell and the base, and each combined power supply unit comprises a first beam, a second beam and a third beam, whereinthe inner ends of the four first beams are fixedly connected to four side faces of the base correspondingly; the outer end of each first beam is connected with a fourth permanent magnet, each fourthpermanent magnet is connected to the lower end of the corresponding second beam, the second beams are connected with third permanent magnets, and the third permanent magnets are connected to the lowerends of the third beams. First permanent magnets with opposite magnetic poles are arranged between the third permanent magnets and the shell, second permanent magnets with opposite magnetic poles arearranged between the fourth permanent magnets and the shell, coils are wound on the permanent magnets, and piezoelectric patches are bound to the lateral surfaces of every three beams. The base and the combined power supply units constitute an L-shaped beam and mass block structure which can be tuned to internal resonance, a piezoelectric power supply structure and an electromagnetic power supplystructure are combined, and large voltage and current can be output.

The invention discloses a bistable vortex-induced vibration energy capture device based on internal resonance, which is composed of a cantilever beam, a piezoelectric sheet, a blunt body with a circular cross section, a permanent magnet, a spring and a load circuit. Placed in the fluid, the vortex-induced vibration generated by the impact of the fluid on the blunt body is used to promote the reciprocating vibration of the cantilever beam, and the kinetic energy of the fluid is converted into electrical energy by means of piezoelectric sheets. The present invention utilizes the nonlinear magnetic repulsion between the permanent magnets to generate a nonlinear restoring force, so that the device generates bistable vibration, and increases linear elasticity to realize the internal resonance phenomenon of the energy harvesting device. The present invention combines the internal resonance effect and the bistable vibration mode Combined with the application to the field of vortex-induced vibration energy capture power generation, it is expected to become an effective way to broaden the working bandwidth of vortex-induced vibration energy capture devices and improve power generation efficiency.

An objective of the present invention is to provide a surface emitting laser capable of selectively generating a laser oscillation in the fundamental mode and thereby emitting a single-wavelength laser light. In a surface emitting laser including an active layer and a two-dimensional photonic crystal provided on one side of the active layer, a reflector 45 or 46 is provided at least at a portion of the circumference of the two-dimensional photonic crystal. The reflector has a reflectance distribution in which the reflectance has a maximum value at a position where the amplitude envelope of the fundamental mode of an internal resonance light created within the two-dimensional photonic crystal. This design strengthens the fundamental mode while suppressing the second mode, thus enabling the laser oscillation in the fundamental mode to be selectively obtained, so that a single-wavelength laser light can be emitted.