156results about How to "Increase modulation bandwidth" patented technology

Integrated optical intensity or phase modulators capable of very low modulation voltage, broad modulation bandwidth, low optical power loss for device insertion, and very small device size are of interest. Such modulators can be of electro-optic or electro-absorption type made of an appropriate electro-optic or electro-absorption material in particular or referred to as an active material in general. An efficient optical waveguide structure for achieving high overlapping between the optical beam mode and the active electro-active region leads to reduced modulation voltage. In an embodiment, ultra-low modulation voltage, high-frequency response, and very compact device size are enabled by a semiconductor modulator device structure, together with an active semiconductor material that is an electro-optic or electro-absorption material, that are appropriately doped with carriers to substantially lower the modulator voltage and still maintain the high frequency response. In another embodiment, an efficient optical coupling structure further enables low optical loss. Various embodiments combined enable the modulator to reach lower voltage, higher frequency, low optical loss, and more compact size than previously possible in the prior arts.

An optical digital external modulator having a cascaded arrangement of interferometers is provided. The optical modulator includes an electrode structure for applying an electric field to each interferometer in the cascade and biasing circuitry coupled to the electrode structure for biasing each interferometer at a predetermined bias point. In particular, each predetermined bias point is selected to be above quadrature and for providing improved transmission performance of digital data signals. Preferably, the modulator has a reflective design that helps to increase the modulation bandwidth, lower the drive voltage, and reduce size.

In one aspect, the invention relates to a semiconductor laser. The laser includes a substrate and an elongate unitary laser structure disposed on the substrate. In turn, the elongate unitary laser structure includes a first laser section, a second laser section, and a plurality of shared layers. The first and second laser sections are capable of lasing independently of each other. The shared layers form both the first laser section and the second laser section. The first laser section is adapted for injection locking the second laser section.

A spatial terahertz wave phase modulator based on the high electron mobility transistor is provided. The phase modulator combines the quick-response high electron mobility transistor with a novel metamaterial resonant structure, so as to rapidly modulate terahertz wave phases in a free space. The phase modulator includes a semiconductor substrate, an HEMT epitaxial layer, a periodical metamaterial resonant structure and a muff-coupling circuit. A concentration of 2-dimensional electron gas in the HEMT epitaxial layer is controlled through loading voltage signals, so as to change an electromagnetic resonation mode of the metamaterial resonant structure, thereby achieving phase modulation of terahertz waves. The phase modulator has a phase modulation depth of over 90 degrees within a large bandwidth, and a maximum phase modulation depth is about 140 degrees. Furthermore, the phase modulator is simple in structure, easy to machine, high in modulation speed, convenient to use, and easy to package.

The invention is an optical A/D converter based on nonsymmetrical Mach-Zehnder modulator, belonging to the optical A/D converter technical field, characterized in that: it uses nonsymmetrical M-Z modulator to modulate electric signal to synchronous multi-wavelength input pulse, and selects proper length difference of two arms DeltaL and N wavelengths, able to make offset of DC biasing point between every two adjacent wavelengths at the outgoing end bepi/N, and the modulated multi-wavelength optical pulse is divided into N synchronous optical pulses by wavelength division multiplexer, and after determined by photoelectric detector and comparer, it can obtain N digital signal outputs. And the invention can implement very large modulated bandwidth and accurately control the offset of DC biasing point of two adjacent channels, implementing higher-digit A/D conversion and easy to implement.

The invention discloses an active area of a laser unit. The active area comprises a multiple-quantum well structure, wherein a potential well layer in the multiple-quantum well structure is made from InGaAsP, and a barrier layer in the multiple-quantum well structure is made from InGaAlAs; a cycle of the multiple-quantum well structure is K, and K ranges from 3 to 20. Furthermore, the invention discloses a semiconductor laser unit and a manufacturing method of the laser unit, wherein the semiconductor laser unit comprises the active area. The semiconductor laser unit provided by the invention has a lower threshold current and higher characteristic temperature, to realize no-refrigeration work; the laser unit has relatively high differential gain, and can provide a laser output in a Tencent Messenger (TM) mode; the laser unit has a relatively high conduction band order, so as to simultaneously restrict injected carriers effectively and distribute the carriers among wells uniformly and enhance the modulation characteristic of the laser unit.

A method of driving a probe of a scanning probe microscope. The intensities of first and second radiation beams are modulated; and the beams are directed simultaneously onto the probe whereby each beam heats the probe and causes the probe to deform, typically by the photothermal effect. The optical system is arranged to direct the centres of the beams onto different locations on the probe. This enables the location of each beam to be chosen to optimise its effect. A lens receives the first and second beams and focuses them onto the probe. A beam combiner is arranged to receive and combine the beams and direct the combined beams towards the probe.

The invention provides a high-speed VCSEL laser epitaxial structure. The laser epitaxial structure comprises a GaAs substrate; a GaAs buffer layer, an N type doped DBR, an active layer, an oxidization limiting layer, a P type doped DBR and an ohmic contact layer are deposited on the GaAs substrate by adopting MOCVD in sequence; and the oxidization limiting layer is formed by multiple Al<1-x>Ga<x>As epitaxial layers with freely adjustable Ga components, wherein X is the Ga element component. According to the laser epitaxial structure, the multiple layers of Al<1-x>Ga<x>As with certain thickness and jumping components are adopted to form the oxidization limiting layer; and the front-end shape of the oxidization limiting layer can be changed by adjusting the components in each layer of Al<1-x>Ga<x>As, so that a lens structure can be formed at the front end of the oxidization limiting layer, and photon scattering loss can be lowered, thereby improving the modulation bandwidth of the VCSEL. The laser epitaxial structure has the following advantages: 1) by adjusting the ratio of Ga in the oxidization limiting layer, the oxidization rate of the oxidization limiting layer is lowered, the oxidization can be controlled easily, and the product yield of the VCSEL chip is improved; and 2) the oxidization limiting layer is high in thickness and low in intrinsic stray capacitance.

The invention discloses a flip-chip structure micro-size photonic crystal LED array chip and a preparation method thereof. The LED array chip of the invention has four light emitting units connected in parallel, the metal connecting line of the positive electrode and the semiconductor material are separated by a dielectric insulation layer, and the negative electrode is directly covered on the upper surface of the semiconductor material. The active region of the light-emitting unit has a photonic crystal with periodic distribution, and the depth of the photonic crystal exceeds the depth of theactive layer. Except electrode pad, DBR is distributed on the whole chip surface. Metal electrodes form metal mirrors. The preparation method of the invention adopts the scheme that an ohmic contactlayer and an electrode are firstly prepared and then a photonic crystal is etched without planarizing and the like traditional process flow; Using thick strip dielectric insulating layer to insulate the electrode from semiconductor material and thin dielectric mask layer and adhesive mask layer to etch together is conducive to the deposition of DBR and the rapid escape of photon mode. The processflow of the invention is simple and reliable.

A method and apparatus for characterizing and compensating optical impairments in an optical transmitter includes operating an optical transmitter comprising a first and second parent MZ, each comprising a plurality of child MZ modulators that are biased at respective initial operating points. An electro-optic RF transfer function is generated for each of the plurality of child MZ modulators. Curve fitting parameters are determined for each of the plurality of electro-optic RF transfer functions and operating points of each child MZ modulator are determined using the curve fitting parameters. An IQ power imbalance is determined using the curve fitting parameters. Initial RF drive power levels are determined that compensate for the determined IQ power imbalance. The XY power imbalance is determined for initial RF drive power levels using the curve fitting parameters. The operating RF drive powers are determined that at least partially compensate for the first and second IQ power imbalances and for the XY power imbalance for the optical transmitter.

The invention discloses a semiconductor laser-pumped kerr lens mode-locked titanium sapphire laser, which comprises first semiconductor lasers, a resonant cavity, an interferometer and a feedback regulation unit, wherein the first semiconductor lasers are used for emitting continuous laser light of blue and green bands to pump titanium sapphire crystal in the resonant cavity; the resonant cavity is used for carrying out oscillating and mode locking on the laser light of near-infrared bands to output femtosecond pulse laser light; the interferometer is used for driving the femtosecond pulse laser light to generate a beat note signal to obtain a carrier-envelope offset frequency; and the feedback regulation unit is used for regulating front and back positions and gradients of end mirrors ofthe resonant cavity and the power of the laser light output by the semiconductor lasers, thereby keeping the stability of a repetition frequency and the carrier-envelope offset frequency. An ultrashort laser light pulse with stable repetition frequency and carrier-envelope offset frequency can be output, and the semiconductor lasers are directly adopted as pumping sources, so that the cost of thelasers is greatly reduced, and the volume of the whole lasers is further reduced.

The invention discloses a linear frequency modulation single frequency pulse optical fiber laser device. The laser device comprises a narrow linewidth seed source, a radio-frequency signal source, an electro-optic modulator driver, a double-parallel phase modulator, an optical fiber beam splitter, an acoustic-optic modulator driver, an acoustic-optic modulator and an optical fiber amplifier. According to the laser device, broadband linear frequency modulation is conducted through the 2*2 MZI structure double-parallel phase modulator, pulse chopping is conducted through the acoustic-optic modulator, and high peak value power output is achieved through the optical fiber amplifier. The laser device has the advantages of being high in peak value power, large in modulation bandwidth, high in modulation speed, high in modulation linearity, simple in structure, capable of achieving the all-fiber laser, safe to human eyes, capable of achieving linear polarization output and capable of satisfying the application requirements of a remote high resolution distance measurement and velocity measurement laser radar for the laser source and can be applied to such fields as remote coherent distance measurement, synthetic aperture/retro-synthetic aperture laser radars and space situation awareness.

A differential drive semiconductor optical modulator includes: a differential driver circuit having output pads which can output a pair of differential signals; a transmission-line substrate having transmission lines connected to the output pads and ground lines; and semiconductor modulators mounted on the transmission-line substrate, arranged in series along a common optical axis; terminal resistors connected to terminal ends of the transmission lines and inductances interposed between the semiconductor modulators and the terminal resistors, on the transmission-line substrate, producing an appropriate optical modulation waveform with a high extinction ratio and enhanced modulation bandwidth.

The present invention discloses a high-speed modulator which comprises an optical waveguide structure and a traveling wave electrode structure, the optical waveguide structure comprises a first optical waveguide arm and a second optical waveguide arm, a traveling wave electrode comprises a grounding electrode and a signal line, and the signal line applies electric fields or voltages in opposite directions to the first optical waveguide arm and the second optical waveguide arm. The first optical waveguide arm and the second optical waveguide arm are both of a folding structure, and the signal line is folded along with the first optical waveguide arm and the second optical waveguide arm, so that an electric field or voltage applied to the first optical waveguide arm and the second optical waveguide arm is kept unchanged. Or the electric field or the voltage applied to the first optical waveguide arm and the second optical waveguide arm is synchronously changed. Compared with the prior art, the device has the advantages that the folding structure of the optical waveguide is matched with the ground-signal-ground coplanar waveguide traveling wave electrode structure, modulation addition of light in different sections of the waveguide is achieved, the longer phase shift waveguide length can be achieved within the limited device length, and meanwhile it can be ensured that the bandwidth meets the application requirement.

The invention discloses a broadband efficient GaN-based LED chip based on surface plasma effect and a preparation method thereof. The broadband efficient GaN-based LED chip is an inversion structure, and successively comprises a substrate, a buffer layer, an unintentional doping GaN layer, a n-GaN layer, a quantum well layer, an electronic barrier layer, a p-GaN layer, a metal reflector layer, a passivation layer, a p-electrode layer, a n-electrode layer, a p-electrode hole and a n-electrode hole from bottom to top. The bottom face, connected with the surface of the p-GaN layer, of the metal reflector layer is provided with a micron-nano compound metal structure. The micron metal structure comprises alternately installed bulge part and groove part. The bulge part is extended to the adjacent place of the quantum well, and the efficient SP-MQW coupling is realized. The p-GaN surface is covered by the groove part, so the p-GaN layer has enough thickness for injecting the hole. The nano-metal structure is distributed on the division surface of the micron-metal structure and the p-GaN.

A device for carrying out electro optical modulation on transmission light based on third order electro optical material consists of coupled prism, metal top electrode, third order organic polymer guide wave layer, modulator formed by isolation layer and metal bottom electrode, and input matching circuit .It is featured as exerting a larger DC bias voltage and a smaller modulation input signal simultaneously on third order organic polymer guide wave layer through input matching circuit to change refractivity of said guide wave layer and so as to change reflectivity at operation angle for realizing modulation on intensity reflection light .

Integration method of a large-scale silicon-based lithium niobate film electro-optic modulator array. By using the method, the difficulty of a fabrication process of a lithium niobate crystal layer is reduced, requirements on precision of bonding lithium niobate and silicon is reduced, and fabrication and bonding of the large-scale array lithium niobate crystal layer can be completed at one time, so that production efficiency of the silicon-based lithium niobate film electro-optic modulator array is greatly improved; through design and optimization of the structure of the silicon crystal layers, light can be naturally alternated and mutually transmitted in silicon waveguides and lithium niobate waveguides, and a high-performance electro-optic modulation effect of the lithium niobate film is achieved.

The invention discloses a lithium niobite membrane QPSK light modulator and a manufacturing method thereof. The light modulator includes a quartz base wafer, lithium niobite membrane, an optical waveguide, a metal membrane electrode and a metallically-packed pipe shell. The method has the following advantages that 1, the length of the crooked waveguide and a traveling wave electrode is shortened,a direct current offset compensation electrode is removed, and the miniaturization of the lithium niobite QPSK light modulator is achieved; 2, a quartz material with a low dielectric constant is adopted as the base wafer of a lithium niobite single crystal membrane, great matching of the microwave refractive index and the optical wave refractive index is achieved, and the modulation bandwidth of the lithium niobite QPSK light modulator is increased; 3, since the direct current offset compensation electrode is removed, the signal processing complexity of the lithium niobite QPSK light modulatoris lowered; 4, the utilization rate of a lithium niobite membrane wafer is increased, and the manufacturing cost of the lithium niobite QPSK light modulator is reduced.

The invention discloses a loading strip-structure silicon/PLZT hybrid waveguide-based Mach-Zehnder electro-optical modulator. The silicon/PLZT hybrid waveguide-based Mach-Zehnder electro-optical modulator comprises a waveguide, an MMI-based Mach-Zehnder interference structure and a coplanar waveguide electrode structure, wherein the waveguide comprises a silicon core layer, a ferroelectric thin film lower coating layer and a silicon dioxide upper coating layer, and the coplanar waveguide electrode structure is designed in order to achieve high-speed electro-optical modulation. The modulator sequentially comprises a coplanar waveguide electrode, the silicon dioxide upper coating layer, a silicon waveguide layer, a PLZT lower coating layer and an NST substrate from top to bottom, wherein thecoplanar electrode can be used for loading a radio frequency signal and loading the radio frequency signal to an optical wave to achieve electro-optical modulation. By the silicon/PLZT hybrid waveguide-based Mach-Zehnder electro-optical modulator, high modulation depth, low transmission loss and high modulation bandwidth can be achieved, and the silicon/PLZT hybrid waveguide-based Mach-Zehnder electro-optical modulator can be applied to an integrated high-speed microwave optical network.

The invention provides an annular-electrode microcavity laser device. The annular-electrode microcavity laser device comprises a substrate, a microcavity laser device formed on the substrate, a first conductive type of patterned electrode made from metal and in an annular shape, and formed at the outer side edge of the top of the microcavity laser device, and a second conductive type of electrode formed on the side surface of the microcavity laser device when the substrate is an insulated substrate, and formed on the back surface of the substrate or the side surface of the microcavity laser device when the substrate is a conductive substrate, wherein the first conductive type and the second conductive type are one of p-type and n-type respectively. According to the annular-electrode microcavity laser device provided by the invention, laser emission mode optical field distribution and carrier distribution are largely superposed in space to acquire a high gain, and then to realize single-mode laser emission.

The invention discloses a data processing method for a THz-grade large-bandwidth laser synthetic aperture radar imaging system, which is composed of a linear tuning semiconductor, a 99:1 optical fiber coupler, a 90:10 optical fiber coupler, an emission collimating lens, a polarized beam splitter, a lambda/4 wave plate, a target displacement platform, a receiving collimating mirror, four 50:50 optical fiber couplers, two balancing detectors, a reference time delay optical fiber, a molecular wavelength reference device, an optical power meter, a data acquisition module and a data processing program module. The laser synthetic aperture radar imaging system disclosed by the invention is based on a large-range linear tuning laser pulse signal; and a target two-dimensional image is calculated according to the homodyne coherent detection technology, the balance detection technology, the synthetic aperture technology and the final special data processing procedure. The system has the advantages of short laser signal wavelength, large bandwidth, high imaging resolution, all-weather characteristic, high stability, simple structure, high detection sensitivity and long acting distance, and most of the system is based on the optical fiber device.

The invention discloses a terahertz wave modulating device with light control flat panel silicon photonic crystal and a method thereof. The terahertz wave modulating device comprises a silicon chip, air holes, a modulated semiconductor laser, a terahertz wave source, an input end of a linear defect area, an output end of the linear defect area, and the linear defect area; the middle of the silicon chip is provided with the linear defect area; the silicon chip on two sides of the linear defect area is provided with the air holes; the silicon chip, the air holes and the linear defect area form the flat panel silicon photonic crystal; the modulated semiconductor laser is arranged above the linear defect area; and terahertz waves emitted by the terahertz wave source are input from the input end of the linear defect area, pass through the linear defect area, and are output from the output end of the linear defect area. The edge of a forbidden band of the flat panel silicon photonic crystal modulates the terahertz waves to realize load signals onto the terahertz waves. The terahertz wave modulating device has the advantages of low transmission loss, large modulation bandwidth, quick modulation speed, high extinction ratio, small size, compact structure, and convenient integration, and meets the communication requirement of the terahertz waves.

The invention discloses a single-mode high-speed modulation Fabry-Perot semiconductor laser based on a coupled cavity, and the laser comprises a tube core which is in a stacked structure and comprises a lower electrode; a lower contact layer which is disposed on the lower electrode; and an N-type substrate which is disposed on the lower contact layer. The N-type substrate is divided into two parts: a Fabry-Perot type miniature cavity and an echo-wall type miniature cavity. The Fabry-Perot type miniature cavity is disposed on the N-type substrate, wherein one end of the Fabry-Perot type miniature cavity is aligned with one end of the N-type substrate. The echo-wall type miniature cavity is disposed on the N-type substrate, and is located at the other end of the Fabry-Perot type miniature cavity. The Fabry-Perot type miniature cavity and the echo-wall type miniature cavity have the same stacked structure. According to the invention, the high-power Fabry-Perot type miniature cavity and the single-mode high-speed modulation echo-wall type miniature cavity are combined together, and the mode coupling between the two cavities is adjusted so as to adjust the equivalent reflectivity of the Fabry-Perot type miniature cavity, thereby achieving high-power, single-mode lasing and better high-speed modulation characteristics.