Abstract: After forming domain inverted layers 3 in an LiTaO3 substrate 1, an optical waveguide is formed. By performing low-temperature annealing for the optical wavelength conversion element thus formed, a stable proton exchange layer 8 is formed, where an increase in refractive index generated during high-temperature annealing is lowered, thereby providing a stable optical wavelength conversion element. Thus, the phase-matched wavelength becomes constant, and variation in harmonic wave output is eliminated. Consequently, with respect to an optical wavelength conversion element utilizing a non-linear optical effect, a highly reliable element is provided.

Abstract: A semiconductor light emitting element of the present invention comprises: a zinc oxide (ZnO) single crystal substrate 12 with a substrate surface of a plane orientation insusceptible to a piezo electric field; a Lattice-matched layer 13 formed on the substrate surface to be lattice-matched with the ZnO single crystal substrate 12; an active layer 15 of indium gallium nitride (InxGa1-xN, 0<x<1); two of cladding layers 14 and 16 to be lattice-matched with the active layer 15 and/or the Lattice-matched layer 13.

Abstract: Vertical cavity light emitting sources that utilize patterned membranes as reflectors are provided. The vertical cavity light emitting sources have a stacked structure that includes an active region disposed between an upper reflector and a lower reflector. The active region, upper reflector and lower reflector can be fabricated from single or multi-layered thin films of solid states materials (“membranes”) that can be separately processed and then stacked to form a vertical cavity light emitting source.

Abstract: A method for making a microchip laser includes preparing a laser-cavity chip assembly comprising a gain media, a first substantially flat surface, and a second substantially flat surface parallel to the first substantially flat surface. The method also includes forming a first reflective film on the first substantially flat surface to form a first cavity mirror, forming a second reflective film on the second substantially flat surface to form a second cavity mirror, and patterning at least one of the first reflective film or the second reflective film by removing at least a portion of the reflective film in the outer portion to form a center reflective portion in the one of the first reflective film or the second reflective film. The first cavity mirror and the second cavity mirror can suppress higher order transverse modes and produce a single TEM00 mode in the lasing light.

Abstract: Provided is a semiconductor laser including: a substrate (semiconductor substrate); an optical waveguide (active layer waveguide) with a mesa structure that includes an active layer (strain-compensated multiple quantum well active layer) including Al, is provided over the semiconductor substrate; a semiconductor protective layer that is provided so as to cover the top and the side of a mesa of the active layer waveguide; a current block layer that is provided so as to embed the active layer waveguide and the semiconductor protective layer; and a clad layer (p-type InP clad layer) that is provided over the semiconductor protective layer and the current block layer, wherein, the semiconductor protective layer has a semiconductor layer (p-type InGaAsP protective layer) that includes As, but does not include Al.

Abstract: The present invention is directed to the integration of a quantum cascade laser with a hollow waveguide on a chip to improve both the beam pattern and manufacturability. By coupling the QCL output into a single-mode rectangular waveguide the radiation mode structure can be known and the propagation, manipulation, and broadcast of the QCL radiation can then be entirely controlled by well-established rectangular waveguide techniques. By controlling the impedance of the interface, enhanced functions, such as creating amplifiers, efficient coupling to external cavities, and increasing power output from metal-metal THz QCLs, are also enabled.

Abstract: Designs of fiber-coupled solid state microcavity light emitters based on microdisk cavities, photonic crystal cavities and other microcavity configurations to provide efficient optical coupling.

Abstract: A plurality of laser diode units is tested in a bar state, each of the laser diode units in which a laser diode that includes a first electrode and a second electrode formed on surfaces facing each other and that is mounted on a mounting surface of a submount such that the first electrode faces the mounting surface of the submount.

Abstract: The laser diode is based on Al In Ga N alloy and consists of: a bottom cladding layer of n-type conductivity, a bottom waveguide layer of n-type conductivity, a light emitting layer, an electron blocking layer of p-type conductivity, an upper waveguide layer of p-type conductivity, an upper cladding layer of p-type conductivity and a subcontact layer, doped with acceptors with concentration level above 1020 cm?3. The diode characterizes in that its bottom cladding layer (1) of n-type is made of GaOxN1-x alloy in which x>0.0005. A method of fabricated such laser diode in epitaxial growth of a layer structure consisting of at least a bottom cladding layer of n-type conductivity comprising at least one GaOxN1-x layer (1, 1a, 1c) in which x>0.0005, consisting in that the GaOxN1-x layer (1a, 1c) is fabricated using a high pressure method of nitride solution in gallium at pressure higher than 800 MPa.

Abstract: A semiconductor laser includes a nitride semiconductor substrate with a striped raised portion that extends in a resonant cavity length direction, a masking layer, which has been defined on the principal surface of the nitride semiconductor substrate and which has a striped opening in a selected area on the upper surface of the striped raised portion, and a nitride semiconductor multilayer structure, which has been grown on the selected area on the upper surface of the striped raised portion. The nitride semiconductor multilayer structure is thicker than nitride semiconductors on the masking layer, and the nitride semiconductor multilayer structure is broader in width than the striped opening of the masking layer and includes portions that have grown laterally onto the masking layer.

Abstract: A semiconductor laser device includes a substrate and a semiconductor layer formed on a surface of the substrate and having a waveguide extending in a first direction parallel to the surface, wherein the waveguide is formed on a region approaching a first side from a center of the semiconductor laser device in a second direction parallel to the surface and intersecting with the first direction, a first region separated from the waveguide on a side opposite to the first side of the waveguide and extending parallel to the first direction and a first recess portion separated from the waveguide on an extension of a facet of the waveguide, intersecting with the first region and extending in the second direction are formed on an upper surface of the semiconductor laser device, and a thickness of the semiconductor layer on the first region is smaller than a thickness of the semiconductor layer on a region other than the first region.

Abstract: A nitride semiconductor laser device includes a multilayer structure including a plurality of nitride semiconductor layers including a light emitting layer, the multilayer structure having cavity facets facing each other, and a plurality of protective films made of a dielectric material provided on one of the cavity facets. The protective films include a first protective film, a second protective film and a third protective film. The first protective film contacts the cavity facet and is made of aluminum nitride. The second protective film is provided on a surface opposite to the cavity facet of the first protective film and is made of a material different from that of the first protective film. The third protective film is provided on a surface opposite to the first protective film of the second protective film and is made of the same material as that of the first protective film.

Abstract: An optical semiconductor device includes: a beam splitter that splits an input optical axis into a first split axis having a first split angle and a second split axis having a second split angle larger than the first split angle; a first unit that is located on the first split axis of the beam splitter and has one or more optical components, an interval between a more distant end of the first unit and the beam splitter having a first length; a second unit that is located on the second split axis of the beam splitter and has one or more optical components, an interval between a more distant end of the second unit and the beam splitter having a second length larger than the first length; and an optical semiconductor element that has a first outputting end having a first output axis coupled optically to the input optical axis of the beam splitter, a second outputting end having a second output axis, and optical gain, the optical semiconductor element being inclined so that the second output axis is arranged away

Abstract: A laser diode having nano patterns is disposed on a substrate. A first conductive-type clad layer is disposed on the substrate, and a second conductive-type clad layer is disposed on the first conductive-type clad layer. An active layer is interposed between the first conductive-type clad layer and the second conductive-type clad layer. Column-shaped nano patterns are arranged at a surface of the second conductive-type clad layer to form a laser diode such as a distributed feedback laser diode.

Abstract: Detecting electrical overstress events in electronic circuitry such as optical emitters. In one example embodiment, a laser includes an active area and a contact region in electrical communication with the active area. A portion of the contact region is configured to manifest a change in a visual attribute of the portion in response to exposure of the portion to an electrical overstress event.

Abstract: A laser assembly and method of operating the assembly are described in which a pump beam is directed through an end-pumped solid-state laser gain medium four or more times. The pump beam is directed at a slight angle through a first end of the medium, reflects off the inner surface of the second, opposite end (to form a “V”), and then reflected by an external or integrated mirror back through the first end and off the inner surface of the opposite end again (back through the “V”).

Abstract: A semiconductor light-emitting device includes an n-type cladding layer formed on a substrate, an active layer formed on the n-type cladding layer and including a well layer and a barrier layer, and a p-type cladding layer formed on the active layer. The well layer is made of an indium-containing nitride semiconductor, and has a hydrogen concentration greater than that of the n-type cladding layer and less than that of the p-type cladding layer.

Abstract: Provided is a III-nitride semiconductor laser diode which is capable of lasing at a low threshold. A support base has a semipolar or nonpolar primary surface. The c-axis Cx of a III-nitride is inclined relative to the primary surface. An n-type cladding region and a p-type cladding region are provided above the primary surface of the support base. A core semiconductor region is provided between the n-type cladding region and the p-type cladding region. The core semiconductor region includes a first optical guide layer, an active layer, and a second optical guide layer. The active layer is provided between the first optical guide layer and the second optical guide layer. The thickness of the core semiconductor region is not less than 0.5 ?m. This structure allows the confinement of light into the core semiconductor region without leakage of light into the support base, and therefore enables reduction in threshold current.

Abstract: A semiconductor optical element includes an n-type substrate, an n-type clad layer formed upward of the n-type substrate, a p-type clad layer formed upward of the n-type substrate, a guide layer, formed between the p-type clad layer and the n-type clad layer, for waveguiding a light, first and second electrodes respectively formed on the bottom surface of the n-type substrate and the upper surface of the p-type clad layer, and a plurality of electric current regulating members provided in the vicinity of the guide layer and regularly arranged along a light waveguide direction in the guide layer. The plurality of electric current regulating members generate an even distribution of a refractive index in the guide layer along the light waveguide direction in the guide layer. The guide layer reflects light with a wavelength which is determined in accordance with the even refractive index distribution.

Abstract: An optoelectronic (OE) package or system and method for fabrication is disclosed which includes a silicon layer with a wiring layer. The silicon layer has an optical via for allowing light to pass therethrough. An optical coupling layer is bonded to the silicon layer, and the optical coupling layer includes a plurality of microlenses for focusing and or collimating the light through the optical via. One or more first OE elements are coupled to the silicon layer and electrically communicating with the wiring. At least one of the first OE elements positioned in optical alignment with the optical via for receiving the light. A second OE element embedded within the wiring layer. A carrier may be interposed between electrical interconnect elements and positioned between the wiring layer and a circuit board.

Abstract: A two terminal semiconductor device for producing light emission in response to electrical signals, includes: a terminal-less semiconductor base region disposed between a semiconductor emitter region and a semiconductor collector region having a tunnel junction adjacent the base region; the base region having a region therein exhibiting quantum size effects; an emitter terminal and a collector terminal respectively coupled with the emitter region and the collector region; whereby application of the electrical signals with respect to the emitter and collector terminals, causes light emission from the base region. Application of the electrical signals is operative to reverse bias the tunnel junction. Holes generated at the tunnel junction recombine in the base region with electrons flowing into the base region, resulting in the light emission. The region exhibiting quantum size effects is operative to aid recombination.

Abstract: Particular embodiments of the present disclosure relate systems and methods for evaluating visible light sources. According to one embodiment, a method of evaluating a visible light source including a semiconductor laser having a gain section, a wavelength selective section, and a phase section includes applying a gain drive signal to the gain section of the semiconductor laser at a gain modulation frequency, and applying a triangular wave drive signal to the wavelength selective section of the semiconductor laser at a wavelength selective modulation frequency that is greater than the gain modulation frequency. The light source emits a plurality of optical output pulses. Output power values of the optical output pulses at a selected wavelength are detected. The output power value of one or more selected output pulses is compared with an output power threshold value to generate an indication of whether the visible light source satisfies an output power specification.

Abstract: A semiconductor optical element has an active layer including quantum dots. The density of quantum dots in the resonator direction in a portion of the active layer in which the density of photons is relatively high is increased relative to the density of quantum dots in a portion of the active layer in which the density of photons is relatively low.

Abstract: A light-emitting element capable of increasing the amount of light emitted, a light-emitting device including the same, and a method of manufacturing the light-emitting element and the light-emitting device include a buffer layer having an uneven pattern formed thereon; a light-emitting structure including a first conductive pattern of a first conductivity type that is conformally formed along the buffer layer having the uneven pattern formed thereon, a light-emitting pattern that is conformally formed along the first conductive pattern, and a second conductive pattern of a second conductivity type that is formed on the light-emitting pattern; a first electrode electrically connected to the first conductive pattern; and a second electrode electrically connected to the second conductive pattern.

Abstract: A light emitting device is provided. The light emitting device comprises: a reflective layer; and a semiconductor layer including a light emitting layer on the reflective layer. A distance between the reflective layer and a center of the light emitting layer corresponds to a constructive interference condition.

Abstract: Compact ASIC, chip-on-board, flip-chip, interposer, and related packaging techniques are incorporated to minimize the footprint of optoelectronic interconnect devices, including the Optical Data Pipe. In addition, ruggedized packaging techniques are incorporated to increase the durability and application space for optoelectronic interconnect devices, including an Optical Data Pipe.

Abstract: A laser medium comprises a solid-state host material and dopant species provided within the solid-state host material. A first portion of the dopant species has a first valence state, and a second portion of the dopant species has a second valence state. In an embodiment, a concentration of the first portion of the dopant species decreases radially with increasing distance from a center of the medium, and a concentration of the second portion of the dopant species increases radially with increasing distance from the center of the medium. The laser medium further comprises impurities within the solid-state host material, the impurities converting the first portion of the dopant species having the first valence state into the second portion of dopant species having the second valence state.

Abstract: A laser-induced optical wiring apparatus is provided wherein optical wiring is realized by digital operations of a laser oscillator. The apparatus includes optical ring resonator formed of a loop-shaped optical waveguide on substrate. At least two optical gain sections are provided on the optical ring resonator. When each optical gain section is activated, a laser oscillator including the optical ring resonator and optical gain sections is enabled to oscillate. In this state, the gain of at least one of the optical gain sections is changed in accordance with an input signal, thereby changing the optical route gain of the optical ring resonator to change the oscillation state of the laser oscillator. A change in the laser oscillation state is detected by the optical gain section other than the at least one optical gain section, whereby an output signal is acquired.

Abstract: A semiconductor gain-structure functions as a gain-element in a laser-resonator. The gain-structure is bonded to a diamond heat-spreader that is peripherally cooled by a heat-sink configured to allow access to the gain-structure by laser-radiation circulating in the laser-resonator. In one example, the gain-structure is used as a transmissive gain-structure in a traveling-wave ring-resonator. In another example, the gain-structure surmounts mirror-structure which functions as an end-mirror of a standing-wave laser-resonator.

Abstract: In a GaN-based laser device having a GaN-based semiconductor stacked-layered structure including a light emitting layer, the semiconductor stacked-layered structure includes a ridge stripe structure causing a stripe-shaped waveguide, and has side surfaces opposite to each other to sandwich the stripe-shaped waveguide in its width direction therebetween. At least part of at least one of the side surfaces is processed to prevent the stripe-shaped waveguide from functioning as a Fabry-Perot resonator in the width direction.

Abstract: Provided is a vertical LED including an n-electrode; an n-type GaN layer formed under the n-electrode, the n-type GaN layer having a surface coming in contact with the n-electrode, the surface having a Ga+N layer containing a larger amount of Ga than that of N; an active layer formed under the n-type GaN layer; a p-type GaN layer formed under the active layer; a p-electrode formed under the p-type GaN layer; and a structure support layer formed under the p-electrode.

Abstract: This method for manufacturing a semiconductor laser apparatus includes steps of forming a first semiconductor laser device having a first electrode, forming a second semiconductor laser device having a second electrode, forming a first solder layer with a first melting point through a first barrier layer on a third electrode, forming a second solder layer with a second melting point through a second barrier layer on a fourth electrode, bonding the first electrode to the third electrode through a first reaction solder layer, a melting point of which rises to a third melting point higher than the second melting point by reacting the first electrode with the first solder layer, and bonding the second electrode to the fourth electrode by applying heat of a first heating temperature to melt the second solder layer with the second melting point after the step of bonding the first electrode to the third electrode.

Abstract: A laser apparatus comprises: a lead frame comprising a first outer lead and a first inner lead connected to the first outer lead; mold resin that has a top surface, does not seal the first outer lead but does seal the first inner lead and cleaves part of the first inner lead exposed on the top surface; a sub-mount comprising a mounting surface and a back surface facing each other, the mounting surface facing the top surface of the mold resin and the back surface being not covered with the mold resin; and a laser element mounted on the mounting surface of the sub-mount and electrically connected to the exposed part of the first inner lead.

Abstract: A nitride semiconductor laser device is formed by growing a group III nitride semiconductor multilayer structure on a substrate. The group III nitride semiconductor multilayer structure has a laser resonator including an n-type semiconductor layer, a p-type semiconductor layer and a light emitting layer held between the n-type semiconductor layer and the p-type semiconductor layer. The laser resonator is arranged to be offset from the center with respect to a device width direction orthogonal to a resonator direction toward one side edge of the device. A wire bonding region having a width of not less than twice the diameter of an electrode wire to be bonded to the device is formed between the laser resonator and the other side edge of the device.

Abstract: A semiconductor laser includes a semiconductor laser region and a wavelength-monitoring region. The semiconductor laser region includes a first optical waveguide that includes a gain waveguide, the first optical waveguide having one end and another end opposite the one end. The wavelength-monitoring region includes a second optical waveguide that is optically coupled to the first optical waveguide with the one end therebetween, and a photodiode structure that is optically coupled to the second optical waveguide. In the wavelength-monitoring region, the second optical waveguide is branched into three or more optical waveguides, and at least two optical waveguides among the three or more optical waveguides form first ring resonators having optical path lengths different from each other.

Abstract: In a structure having a two-dimensional photonic crystal in which structures having different refractive indices are disposed at a two-dimensional period and comprising a structure emitting in a direction perpendicular to a resonance direction of light propagating in the in-plane direction of the two-dimensional photonic crystal, wherein the structure comprises a one-dimensional photonic crystal in which components having different refractive indices are arranged at a one-dimensional period, and, the light propagating in the in-plane direction of the two-dimensional photonic crystal is reflected by a photonic band edge of the one-dimensional photonic crystal.

Abstract: A semiconductor laser device includes a laser diode provided on a semiconductor substrate, the laser diode including a first optical waveguide having a gain waveguide, a plurality of photodiodes, a first wavelength-selective filter having periodic transmission peaks, and a second wavelength-selective filter having periodic transmission peaks, the period of the transmission peaks of the second wavelength-selective filter being different from the period of the transmission peaks of the first wavelength-selective filter. Furthermore, two photodiodes among the plurality of photodiodes are optically coupled to the first optical waveguide through the first and second wavelength-selective filters, respectively.

Abstract: A semiconductor laser comprises: a substrate; an n-cladding layer disposed on the substrate; an active layer disposed on the n-cladding layer; a p-cladding layer disposed on the active layer and forming a waveguide ridge; and a diffraction grating layer disposed between the active layer and the n-cladding layer or the p-cladding layer and including a phase shift structure in a part of the diffraction grating layer in an optical waveguide direction. The width of the p-cladding layer is increased in a portion corresponding to the phase shift structure of the diffraction grating layer.

Abstract: A nitride based semiconductor device includes: an n-type cladding layer; an n-type GaN based guide layer placed on the n-type cladding layer; an active layer placed on the n-type GaN based guide layer; a p-type GaN based guide layer placed on the active layer; an electron block layer placed on the p-type GaN based guide layer; a stress relaxation layer placed on the electron block layer; and a p-type cladding layer placed on the stress relaxation layer, and the nitride based semiconductor device alleviates the stress occurred under the influence of the electron block layer, does not affect light distribution by the electron block layer, reduces threshold current, can suppress the degradation of reliability, can suppress degradation of the emitting end surface of the laser beam, can improve the far field pattern, and is long lasting, and fabrication method of the device is also provided.

Abstract: Provided are a group-III nitride semiconductor laser device with a laser cavity to enable a low threshold current on a semipolar surface of a hexagonal group-III nitride, and a method for fabricating the group-III nitride semiconductor laser device on a stable basis. Notches, e.g., notch 113a and others, are formed at four respective corners of a first surface 13a located on the anode side of a group-III nitride semiconductor laser device 11. The notch 113a or the like is a part of a scribed groove provided for separation of the device 11. The scribed grooves are formed with a laser scriber and the shape of the scribed grooves is adjusted by controlling the laser scriber. For example, a ratio of the depth of the notch 113a or the like to the thickness of the group-III nitride semiconductor laser device 11 is not less than 0.05 and not more than 0.

Abstract: The nitride semiconductor laser device includes a substrate, a nitride semiconductor layer having a first nitride semiconductor layer, an active layer, and a second nitride semiconductor layer stacked in this order on the substrate, and a ridge provided on a surface of the nitride semiconductor layer. The surface of the nitride semiconductor layer includes a generally flat part and first and second grooves which extend along the ridge in a resonator direction, the first groove being formed continuous to a first side surface of the ridge, the second groove being formed continuous to a second side surface of the ridge which is opposite to the first side surface.

Abstract: A light emission device includes: first and second clad layers sandwiching an active layer; a first electrode connected with the first clad layer; and second electrodes connected with the second clad layer, at least part of the active layer forms gain areas corresponding to the second electrodes, the gain areas extend from a first side to a second side of the active layer while inclined to a vertical of the first side, at least first and second gain areas form a set of gain areas and a plurality of sets are provided, the first and second gain areas in each set are disposed perpendicular to a direction extending from the first side to the second side, the second electrodes above the first gain areas are interconnected by a first common electrode, and the second electrodes above the second gain areas are interconnected by a second common electrode.

Abstract: A laser diode capable of independently driving each ridge section, and inhibiting rotation of a polarization angle resulting from a stress applied to the ridge section without lowering reliability and a method of manufacturing the same are provided. A laser diode includes: three or more strip-like ridge sections in parallel with each other with a strip-like trench in between, including at least a lower cladding layer, an active layer, and an upper cladding layer in this order; an upper electrode on a top face of each ridge section, being electrically connected to the upper cladding layer; a wiring layer electrically connected to the upper electrode, in the air at least over the trench; and a pad electrode in a region different from regions of both the ridge section and the trench, being electrically connected to the upper electrode through the wiring layer.

Abstract: A process for fabricating lasers capable of emitting blue light wherein a GaN wafer is etched to form laser waveguides and mirrors using a temperature of over 500° C. and an ion beam in excess of 500 V in CAIBE.

Abstract: A light emitting device includes: a semiconductor laser element having a first emission face for emitting laser light; a light guiding body buried in the concave portion of the supporting base, guiding the laser light emitted from the semiconductor laser element, and having an incident face to which the laser light enters, and a second emission face from which the laser light traveling through the light guiding body is emitted, the incident face of the light guiding body being such a curved face that an incident angle of the laser light is within a predetermined range including the Brewster angle in a plane formed by a traveling direction of the laser light and a short axis of a light emitting spot of the laser light; and a fluorescent substance scattered in the light guiding body, absorbing the laser light, and emitting the light having a different wavelength from a wavelength of the laser light.

Abstract: A wavelength conversion structure includes a light guide formed of a light-transmissive member having a laser light incident port that allows the laser light to be introduced and a phosphor-containing layer that covers at least part of the surface of the light guide. The light guide has a light diffusing structure having asperities formed over the surface of the light guide except a laser light incident surface having the laser light incident port and a light reflecting film formed over the surface of the light guide along the asperities except the laser light incident port and the portion covered with the phosphor-containing layer.

Abstract: A gain medium and an interband cascade laser, an interband cascade amplifier, and an external cavity laser having the gain medium are presented.

Abstract: Multi-quantum well laser structures are provided comprising active and/or passive MQW regions. Each of the MQW regions comprises a plurality of quantum wells and intervening barrier layers. Adjacent MQW regions are separated by a spacer layer that is thicker than the intervening barrier layers. The bandgap of the quantum wells is lower than the bandgap of the intervening barrier layers and the spacer layer. The active region may comprise active and passive MQWs and be configured for electrically-pumped stimulated emission of photons or it may comprises active MQW regions configured for optically-pumped stimulated emission of photons.

Abstract: A semiconductor laser diode apparatus capable of suppressing variation in an emission position and an emission direction of a laser beam emitted from a semiconductor laser diode element is obtained. This semiconductor laser diode apparatus includes a semiconductor laser diode element having warping along either a first direction in which a cavity extends or a second direction intersecting with the first direction and a base on which a convex side of the warping of the semiconductor laser diode element is fixed, wherein a distance between a first end of the semiconductor laser diode element in a direction of larger warping among the first and second directions and the base is smaller than a distance between a second end of the semiconductor laser diode element in the direction of the large warping among the first and second directions and the base.

Abstract: A structure including a grating and a semiconductor nanocrystal layer on the grating, can be a laser. The semiconductor nanocrystal layer can include a plurality of semiconductor nanocrystals including a Group II-VI compound, the nanocrystals being distributed in a metal oxide matrix. The grating can have a periodicity from 200 nm to 500 nm.