2293results about "Optical resonator shape and construction" patented technology

A vertical-cavity surface-emitting laser (VCSEL) comprising a low-loss thin metal contact and current spreading layer within the optical cavity that provides for improved ohmic contact and lateral current distribution, a substrate including a plano-concave optical cavity, a (Ga,In,Al)N multiple quantum well (MQW) active region contained within the optical cavity that generates light when injected by an electrical current, and an integrated micromirror fabricated onto the substrate that provides for optical mode control of the light generated by the active region. A relatively simple process is used to fabricate the VCSEL.

Organic vertical-cavity surface-emitting lasers ("OVCSELs"), in which a thin layer of organic material is disposed between highly reflective mirrors to thereby form a vertical cavity within a stacked arrangement. The lasers of the present invention each comprise a first mirror layer; a layer of active organic material over the first mirror layer; and a second mirror layer over the layer of first active organic material. The active organic material lases when pumped to thereby produce laser light. The present invention provides for optical semiconductor lasers with desired properties such as narrow bandwidth emission, the minimal use of active organic materials, and the facilitation of wavelength tuning and electrical pumping.

An annular metal layer is provided between a conductive oxide layer and a dielectric mirror in a vertical cavity surface emitting laser. The annular metal layer defines the output window for the laser cavity which matches the TEM.sub.00 fundamental mode of the light beam emitted by the active region of the VCSEL. The metal layer outside the output window provides modal reflectivity discrimination against high order transverse modes of the light beam emitted by the active region of the VCSEL.

There is provided a beam homogenizer which can unify the energy distribution of a linear laser beam in a longitudinal direction. In the beam homogenizer including cylindrical lens groups for dividing a beam, and a cylindrical lens and a cylindrical lens group for condensing the divided beams, the phases, in the longitudinal direction, of linear beams passing through individual cylindrical lenses of the cylindrical lens group for condensing the divided beams are shifted, and then, the beams are synthesized, so that the intensity of interference fringes of the linear beam on a surface to be irradiated is made uniform.

An apparatus and source arrangement for filtering an electromagnetic radiation can be provided which may include at least one spectral separating arrangement configured to physically separate one or more components of the electromagnetic radiation based on a frequency of the electromagnetic radiation. The apparatus and source arrangement may also have at least one continuously rotating optical arrangement which is configured to receive at least one signal that is associated with the one or more components. Further, the apparatus and source arrangement can include at least one beam selecting arrangement configured to receive the signal.

Arrays of vertical extended cavity surface emitting lasers (VECSELs) are disclosed. The functionality of two or more conventional optical components are combined into an optical unit to reduce the number of components that must be aligned during packaging.

A resonant grating structure in a waveguide and methods of tuning the performance of the grating structure are described. An apparatus includes a waveguide; and a subwavelength resonant grating structure embedded in the waveguide. The systems and methods provide advantages including narrowband filtering capabilities, minimal sideband reflections, spatial control, high packing density, and tunability.

In a method for producing a resonant cavity light emitting device, a seed gallium nitride crystal (14) and a source material (30) are arranged in a nitrogen-containing superheated fluid (44) disposed in a sealed container (10) disposed in a multiple-zone furnace (50). Gallium nitride material is grown on the seed gallium nitride crystal (14) to produce a single-crystal gallium nitride substrate (106, 106′). Said growing includes applying a temporally varying thermal gradient (100, 100′, 102, 102′) between the seed gallium nitride crystal (14) and the source material (30) to produce an increasing growth rate during at least a portion of the growing. A stack of group III-nitride layers (112) is deposited on the single-crystal gallium nitride substrate (106, 106′), including a first mirror sub-stack (116) and an active region (120) adapted for fabrication into one or more resonant cavity light emitting devices (108, 150, 160, 170, 180).

A laser diode device operable at a one or more wavelength ranges. The device has a first waveguide provided on a non-polar or semipolar crystal plane of gallium containing material. In a specific embodiment, the first waveguide has a first gain characteristic and a first direction. In a specific embodiment, the first waveguide has a first end and a second end and a first length defined between the first end and the second end. The device has a second waveguide provided on a non-polar or semipolar crystal plane of gallium containing material. In a specific embodiment, the second waveguide has a second gain characteristic and a second direction. In a specific embodiment, the second waveguide has a first end, a second end, and a second length defined between the first end and the second end. In a specific embodiment, the second waveguide has the first end being coupled to the first end of the first waveguide. The second length is in a different direction from the second length. In a specific embodiment, the device has a cleaved region provided on the second end of the second waveguide, the cleaved region being perpendicular to the second direction of the second waveguide.

A device including an input port configured to receive an input signal is described. The device also includes an output port and a structure, which structure includes a tunneling junction connected with the input port and the output port. The tunneling junction is configured in a way (i) which provides electrons in a particular energy state within the structure, (ii) which produces surface plasmons in response to the input signal, (iii) which causes the structure to act as a waveguide for directing at least a portion of the surface plasmons along a predetermined path toward the output port such that the surface plasmons so directed interact with the electrons in a particular way, and (iv) which produces at the output port an output signal resulting from the particular interaction between the electrons and the surface plasmons.

External Cavity Laser An external cavity laser comprising first and second feedback means with an optical gain medium (2) therebetween, one of the feedback means is provided by a grating (4) formed in a silicon waveguide and the other feedback means is provided by a reflective back facet (2B) of the optical gain medium (2). The output wavelength of the laser, at a given temperature, can thus be determined during its manufacture and the laser can be made by mass production techniques. The grating (4) may be thermally isolated to obviate the need for temperature control means (6) to control the temperature of the grating (4). An array of lasers may be provided on a single chip.

A gain medium 12 and a tunable filter are provided in an optical path of laser oscillation. The tunable filter has an optical beam deflector for periodically changing an optical beam at a constant angular speed, a prism 26 on which deflected light is made incident, and a diffraction grating 27. Appropriate selection of the apex angle α of the prism 26 and an angle β formed by the prism 26 and the diffraction grating 27 can provide a tunable laser light source for changing the oscillation frequency at high speed and a constant variation rate.

The present invention provides a continuously tunable external cavity laser (ECL) with a compact form factor and precise tuning to a selected center wavelength of a selected wavelength grid. The ECL may thus be utilized in telecom applications to generate the center wavelengths for any channel on the ITU or other optical grid. The ECL does not require a closed loop feedback. A novel tuning mechanism is disclosed which provides for electrical or mechanical tuning to a known position or electrical parameter, e.g., voltage, current or capacitance, with the required precision in the selected center wavelength arising as a result of a novel arrangement of a grid generator and a channel selector. The grid generator exhibits first pass bands which correspond to the spacing between individual channels of the selected wavelength grid and a finesse which suppresses side band modes of the laser. The channel selector exhibits second pass bands that are wider than the first pass bands. In an embodiment of the invention the second pass bands have a periodicity substantially corresponding with the separation between the shortest wavelength channel and the longest wavelength channel of the selected wavelength grid and a finesse which suppresses channels adjacent to the selected channel. The broad second pass bands of the channel selector reduce the sensitivity of the ECL to tuning variations about the selected channel, thus avoiding the requirement of a closed loop feedback system to control the channel selector.

A process for operation of a laser device (1) is described, whereby circulating light pulses each comprising spectral components according to a plurality of longitudinal modes of a resonator configuration (3) are generated in the resonator configuration (3) and subjected to a compensation of group velocity dispersion, and a predetermined linear dispersion is introduced into the light path of the resonator configuration (3), so that at least one mode has a predetermined frequency and/or the mode distance between the modes has a predetermined value. Furthermore, regulations for stabilizing the laser device on the basis of this process and applications of the regulations for the generation for stabilized, ultra-short light pulses, generation of optical frequencies and in the frequency and/or time measuring technique as well as in the spectroscopy are described.

When a ratio R between a total angle φ of a widening angle in a median intensity of light of a light source (a GaN based semiconductor laser) and a total angle 2/φ of a widening angle of light defining a numerical aperture NA of a collimator optical system (collimator lens) is defined as R=(sin⁻¹NA)×2/φ, the numerical aperture of the collimator optical system (collimator lens) is set so that 2.0≧R≧0.58. Thus, an image exposure device is provided that can suppress stray light of a light source that emits a large amount of stray light.

A tunable optical source comprises a laser diode and an external optical feedback device. The feedback device has a waveguiding portion fabricated at least in part out of a glass material having both organic and inorganic components. A control device is provided for controlling the refractive index of the glass material so as to change the wavelength of feedback to the laser diode. The glass material may for example have thermo-optic properties and the control device might then be a heating device for heating the glass material. The feedback device can have more than one portion, a second portion for example having controllable coupling characteristics for coupling optical radiation into or out of the feedback device. It also preferably has a portion for controlling optical path length in the feedback device.

A fiber laser with a fiber for laser light generation having an entrance end and an exit end comprises a pump light source for generating pump light to be coupled via the entrance side into the fiber. At the exit end of the fiber a first resonator mirror is provided which is highly reflecting for the laser light to be generated in the wavelength range with the smallest light amplification and to the light of the pump light source. Spaced from the first resonator mirror a second resonator mirror is provided via which light of further wavelength ranges can be fed back into the fiber with the aid of a collimating lens.

An optical fiber loop has a gain medium having a gain at an oscillation wavelength and optical circulators 13 and 14. Collimate lenses 22 and 24 enlarge light bean taken from the optical circulators 13 and 14. A polygon mirror 25 is provided on the light axis, and is rotated. A diffraction grating 27 is provided at the receiving position of the light reflected by the polygon mirror 25, and is of a Littrow configuration which reflects the light in the same direction as the incident light. A selected wavelength changes according to an incident angle to the diffraction grating 27, resulting in increase of selectivity owing to twice incident, thereby permitting to change an oscillation wavelength with narrow band even when changing the selected wavelength by rotating the polygon mirror 25 at high speed.

A display apparatus for producing colored pixelated light includes a backlight unit for providing a pump-beam light. The apparatus also includes a microcavity light-producing array responsive to pump-beam light and having pixels wherein each pixel including a transparent substrate, a bottom dielectric stack reflective to light over a predetermined range of wavelengths, an active region responsive to pump-beam light for producing display light, and a top dielectric stack spaced from the bottom dielectric stack and reflective to light over a predetermined range of wavelengths. The apparatus further includes a light shutter for permitting selected display light from the microcavity light-producing array to pass therethrough, a polarizing layer disposed between the microcavity light-producing array and the light shutter, and a beam expander disposed over the light shutter for increasing the angular cone of view of the display light.

A wavelength discretely tunable semiconductor laser that addresses wide wavelength tuning range, is mode hopping free, has high output power, has fast wavelength switching time, is wavelength locking free and is relatively simple. Four exemplary embodiments disclosed herein utilize a wavelength discretely tunable semiconductor laser that comprises a discretely tunable filter and laser amplifier. In the first embodiment, the tuning element comprises a pair of cascade Fabry-Perot filters, each having a plurality of characteristic narrow transmission passbands that pass only the cavity mode under the passband. The spacing between the narrow transmission passbands are slightly different in one filter from the other filter so that only one passband from each filter can be overlapped in any given condition over the entire active element gain spectral range, thereby permitting lasing only at a single cavity mode passed by the cascade double filters. One of the two etalon filters can be made with a plurality of transmission passbands predetermined by industry, application and international standards, making this element an intra-cavity wavelength reference and eliminating further wavelength locking needs for the tunable laser. In a second embodiment, one of the two etalons is replaced by a wedge filter. The filter optical path change and thus the transmission passband shift are achieved by translating the wedge filter in a direction perpendicular to the optical axis. In a third embodiment, one of the two etalon filters is replaced by a polarization interference filter. The polarization interference filter consists of an electro-optically-tunable birefringent waveplate, a fixed birefringent waveplate, the laser cavity and T.E. polarization light emitted from the laser diode. In a fourth embodiment, the laser and wavelength tuning structure are integrated on a semiconductor substrate by epitaxy processes.

Arrays of vertical extended cavity surface emitting lasers (VECSELs) are disclosed. The functionality of two or more conventional optical components are combined into an optical unit to reduce the number of components that must be aligned during packaging. A dichroic beamsplitter selectively couples frequency doubled light out of the cavity. In one implementation the dichroic beamsplitter includes at least one prism.

Apparatus and methods that utilize tunable elements to provide for selective wavelength tuning of a light beam. The apparatus comprises a first tunable wavelength selection element having a first adjustable free spectral range, a second tunable wavelength selection element having a second adjustable free spectral range, with the first and second tunable wavelength selection elements configured to define a tunable joint transmission peak. The first and second tunable wavelength selection elements respectively define first and second pluralities of tunable transmission peaks, wherein respective ones of each of the first and second plurality of transmission peaks are aligned to obtain a joint transmission peak that may be adjusted by tuning the wavelength selection elements. The free spectral ranges of the wavelength selection elements are configured to enable a Vernier tuning effect.

Photonic integrated circuits on silicon are disclosed. By bonding a wafer of compound semiconductor material as an active region to silicon and removing the substrate, the lasers, amplifiers, modulators, and other devices can be processed using standard photolithographic techniques on the silicon substrate. A silicon laser intermixed integrated device in accordance with one or more embodiments of the present invention comprises a silicon-on-insulator substrate, comprising at least one waveguide in a top surface, and a compound semiconductor substrate comprising a gain layer, the compound semiconductor substrate being subjected to a quantum well intermixing process, wherein the upper surface of the compound semiconductor substrate is bonded to the top surface of the silicon-on-insulator substrate.

A modular light emitting diode (LED) mounting configuration is provided including a light source module having a plurality of pre-packaged LEDs arranged in a serial array. The module is connected to a heat dissipating plate configured to mount to an electrical junction box. Thus, heat from the LEDs is conducted to the heat dissipating plate and to the junction box. A sensor is configured to detect environmental parameters and a driver is configured to illuminate the LEDs in response to the environmental parameters, thereby selectively configuring the LEDs to function in a wide variety of useful applications.

An active gain region sandwiched between a 100% reflective bottom Bragg mirror and an intermediate partially reflecting Bragg mirror is formed on a lower surface of a supporting substrate, to thereby provide the first (“active”) resonator cavity of a high power coupled cavity surface emitting laser device. The reflectivity of the intermediate mirror is kept low enough so that laser oscillation within the active gain region will not occur. The substrate is entirely outside the active cavity but is contained within a second (“passive”) resonator cavity defined by the intermediate mirror and a partially reflecting output mirror, where it is subjected to only a fraction of the light intensity that is circulating in the gain region. In one embodiment, non-linear optical material inside each passive cavity of an array converts an IR fundamental wavelength of each laser device to a corresponding visible harmonic wavelength, and the external output cavity mirror comprises a Volume Bragg grating (VBG) or other similar optical component that is substantially reflective at the fundamental frequency and substantially transmissive at the harmonic frequency. The VBG used in an array of such devices may be either flat, which simplifies registration and alignment during manufacture, or may be configured to narrow the IR spectrum fed back into the active resonant cavity and to shape the spatial mode distribution inside the cavity, thereby reducing the size of the mode and compensating for any deformations in the semiconductor array.

An external cavity laser has a mirror-based resonant tunable filter, such as a Fabry Perot tunable filter or Gires-Tournois interferometer tuning element, with the tunable filter being preferably used as a laser cavity mirror. A mirror-based resonant tunable filter is selected in which the spectral response in reflection has an angular dependence. A tilt scheme is used whereby by selecting an appropriate angle between the filter's nominal optical axis and the cavity optical axis, a narrowband peak spectral reflection is provided to the laser cavity. This tunable narrowband spectral reflection from the filter is used to lock and tune the laser output wavelength.

A tunable transmissive grating comprises a transmissive dispersive element, a reflective element, and an angle θ formed between the two elements. A first optical path is formed according to the angle θ, wherein light dispersing from the dispersive element is directed onto the reflective element and reflects therefrom. At least one element is rotatable about a rotational center to cause a second optical path and thereby tune the wavelength of the light reflecting from the reflective element. Both elements can be rotatable together around a common rotational center point according to certain embodiments, and/or each element can be independently rotated around a rotational axis associated only with that element. According to some embodiments, the relative angle θ formed between the elements is held constant; however, in other embodiments θ can vary.

An external cavity mirror for use in a semiconductor laser, the external cavity mirror comprising a waveguide formed on a substrate of highly electro-optic material, and including electrically-operated means for determining the reflectance attributes of the external cavity mirror.

The invention pertains to wavelength-agile optical filters suitable for wavelength-division-multiplexed (WDM) optical communications networks. More particularly, the invention pertains to optical filters with a wavelength reference that can be remotely switched to arbitrarily selectable channels on a standard grid, and to re-configurable optical communications networks employing same. The present invention provides a communication apparatus with a tunable filter which may be used in a wide range of applications including tuning an external cavity laser (ECL), selecting a wavelength for an add/drop multiplexer and providing channel selection and feedback for a wavelength locker. The filter may be utilized as a discrete component or in combination with circulators, wavelength lockers and gain medium. The filter may be implemented in whole or in part as part of a gain medium. The tunable filter exhibits a compact form factor and precise tuning to any selected wavelength of a predetermined set of wavelengths comprising a wavelength grid. The tunable filter may thus be utilized in telecom applications to generate the center wavelengths for any channel on the ITU or other optical grid.

A color laser display apparatus which contains a laser light source which emits ultraviolet laser light, a modulation unit which modulates the ultraviolet laser light, a display unit which includes a fluorescent screen, and a scanning unit which two-dimensionally scans the fluorescent screen with the ultraviolet laser light. The fluorescent screen includes, for each pixel, red fluorescent material which emits red light in response to the ultraviolet laser light, green fluorescent material which emits green light in response to the ultraviolet laser light, and blue fluorescent material which emits blue light in response to the ultraviolet laser light. The laser light source may be, for example, a semiconductor laser or a fiber laser.