University of Central Florida Research Foundation, Inc.

Optigrate Corporation

Fujitsu Corporation

University of Michigan

Accudyne Display and Semiconductor Systems, Inc.

Leonid B Glebov

Vadim Smirnov

Ivan Divliansky

Larissa Glebova

Boris Zeldovich

Julien Lumeau

George Venus

Almantas Galvanauskas

Oleg Efimov

Evan Hale

Sergiy Mokhov

Nelson V Tabirian

Kishio Yokouchi

Alexei L Glebov

Sarik R Nersisyan

Brian L Hoekstra

Lam Mach

Bahaa Saleh

Eugeniu Rotari

Oleksiy Andrusyak

Leo A Siiman

Emilie Flecher

Kai-Hsiu Liao

Vasile Rotar

Brian Anderson

Oleg M Efimov

Daniel Ott

A phase-shifted longitudinally-chirped volume Bragg grating (PS-LCVBG) may be formed as a solid block of photosensitive material having a planar input face, where the photosensitive material includes a VBG formed as a periodic volumetric refractive index distribution characterized by a grating vector direction. A period of the VBG may longitudinally chirped to vary linearly along the grating vector direction. The VBG may further include a spatially-varying distribution of longitudinal phase shifts providing a spatially-varying distribution of reflectivity in a transverse plane normal to the grating vector direction, where light incident on the planar input face is at least partially reflected based on the spatially-varying distribution of reflectivity.

Phase-shifted, chirped volume Bragg gratings

A phase converting device capable of use over a broad wavelength range, which may be used for optical beam transformations and combining, conversion of resonator and waveguide modes, correction of aberrations in optical systems, and selection of photons with specific phase profile. This provides significant advantages in high power laser systems. Large-mode-area fibers can be used to provide higher incident powers than can be achieved by single-mode fibers, reducing the number of elements in a system necessary to achieve the desired output. The profiles of these LMA fiber modes can then be converted from the undesired modes into the desired mode while combing their total power into a single beam.

Achromatic holographic phase masks, methods, and applications

Complex spectral and angular diffractive optical elements in photosensitive materials based on Moir&#xe9; pattern are proposed and demonstrated. The process is based on the recording of multiple volume Bragg gratings with controlled difference of the periods in the same volume of photosensitive material. Filters with ultra-narrow bandpass in the range of a few picometers to a few tens of picometers or apodized diffractive optical elements across large aperture are demonstrated. Several methods to fabricating such Moir&#xe9; Bragg gratings are proposed. Experimental demonstration of a Moir&#xe9; ultra-narrowband diffractive optical element in PTR glass is performed.

Volume Moir&#xe9; Bragg gratings in a photosensitive material

A method of reversible spatial mode selection and conversion between waveguides and free space is presented using a multiplexed volume Bragg grating (MVBG). The MVBG has an inherent angular selectivity, providing different losses for different transverse modes and converting a higher order mode in waveguide to a single fundamental mode in free space. Using the device in a resonator allows for a pure higher order mode to be guided and amplified in the gain medium, to increase the mode area, to extract accumulated excitation more efficiently, and, therefore, to increase gain of the amplifier. In the same resonator, the device is able to convert the higher order mode to a high brightness Gaussian beam in free space or to a fundamental mode in a waveguide.

Optical system including multiplexed volume Bragg grating, methods, and applications

Recent invention of longitudinally chirped volume Bragg gratings has dramatically changed a design of high power femtosecond lasers. Replacing of bulky pairs of conventional surface gratings with compact and robust chirped volume Bragg gratings for stretching and compression of laser pulses in chirped-pulse-amplification systems enabled decrease of size and weight of those systems by several times. The methods and devices enable substantial increase of stretching time and compression to shorter pulses, enhancement of stretched and compressed beams quality by stationary or dynamic shaping of gratings, and shaping of laser pulses in both temporal and spectral domains.

Laser pulse temporal, spectral and spatial shaping devices based on volume diffractive gratings with spatially variable parameters

Apparatus, methods and systems for production of high efficiency refractive and diffractive elements by providing a photo-sensitizer free multicomponent glass, exposing the multi component glass to pulsed laser radiation to produce refractive indexed modulation, and heating the exposed multicomponent silicate glass to produce the high efficiency refractive and diffractive elements. The pulsed laser radiation is infrared femtosecond pulses to ultraviolet nanosecond pulses which provide ionization of glass matrix. The multicomponent glass is a photosensitive glass with high transparency in ultraviolet spectral region, e.g. silicate glass which includes silver, fluorine and bromine and does not contain photosensitizers such as cerium and antimony, PTR glass, cerium free PTR glass and cerium+antimony free PTR glass.

Production of high efficiency diffractive and refractive optical elements in multicomponent glass by nonlinear photo-ionization followed by thermal development

A volume Bragg laser including a resonator comprising photo-thermo-refractive (PTR) volume diffractive elements that can be used in a laser emitting window of transparency of PTR glass to provide control of the lasers spectral and angular parameters, and methods, devices, apparatus and systems related thereto. The high efficiency volume Bragg gratings recorded in photo-thermo-refractive (PTR) glass preferably has an absolute diffraction efficiency exceeding approximately 95% in transmitting and reflecting modes is used for selection of a transverse and longitudinal mode for thermal, optical and mechanical stabilization of the volume Bragg lasers and coherent coupling of different lasers. Robustness, compactness, thermal and laser stability along with the ability to place several elements in the same space allows the use of sophisticated optical system according to the invention in fields of military lasers, optical communications, data storage and processing, and the like.

Volume Bragg lasers based on high efficiency diffractive elements in photo-thermo-refractive glass

High efficiency reflective volume Bragg gratings with chirped gratings recorded in photo-thermo-refractive glass having an absolute diffraction efficiency exceeding 95% in transmitting and reflecting modes are used to stretch and/or compress ultrashort laser pulses with high efficiency. Robustness, compactness, thermal and laser stability along with placement of multiple elements in the same space provides femtosecond laser system with high efficiency of stretching and re-compression of femtosecond pulses.

Stretching and compression of laser pulses by means of high efficiency volume diffractive gratings with variable periods in photo-thermo-refractive glass

Volume bragg lasers based on high efficiency diffractive elements in photo-thermo-refractive glass

Photo-thermo-refractive (PTR) glass is a multi-component silicate glass having photosensitivity in rear UV region. A novel process is disclosed for PTR glass sensitization to visible region by means of two-step illumination followed by thermal development. This disclosed process utilizes a first illumination at approximately 325 nm followed by a second illumination with radiation in the visible spectral region out of the region of original photosensitivity of the PTR glass which enables fabrication of complex holographic optical elements for visible region such as plane elements, lenses, curved mirrors, combinations of complex elements and optical correlators. The same process provides a positive increment of refractive index in the bulk of the PTR glass and, therefore, can be used for refractive optical elements recording, such as lenses and waveguides.

Sensitization of photo-thermo-refractive glass to visible radiation by two-step illumination

Non-mechanical optical beam steering and switching is produced by optically controlled liquid crystal spatial light modulator with angular magnification by high efficiency volume Bragg gratings recorded in a photosensitive PTR glass. Small angle beam deflection in a photoactive liquid crystal cell is produced by exposing it to a controlling beam from an external source of radiation with predetermined distribution of power density which causes predetermined spatial gradients of a refractive index in a liquid crystal cell and, therefore, refraction of a controlled beam which is made to propagate in the region with spatial gradient of the refractive index. Large angle beam deflection is produced by a volume Bragg grating with angular selectivity adjusted in such way that small angle scanning produced by optically controlled liquid crystal spatial light modulator results in change of diffraction efficiency from zero to 100% for switching the beam for two Bragg angles.

Optical beam steering and switching by optically controlled liquid crystal spatial light modulator with angular magnification by high efficiency PTR Bragg gratings

The present invention provides an optical interconnection platform, comprising a substrate, a plurality of integrated circuits attached to a surface of the substrate wherein each integrated circuit having an array of transmitters and an array of receivers, an optical integrated circuit module attached to an opposing surface of the substrate wherein the optical integrated circuit module comprising a highly transparent photosensitive material having an input microlens that collimate the light beams before entering the optical integrated circuit module and an output microlens that focuses the light beams into the array of receivers, and input and output Bragg diffractive gratings that are formed inside of the optical integrated circuit module.

Optical interconnect platform including Bragg diffractive gratings in a bulk material

Novel volume holographic elements were made from Bragg diffractive gratings in photo-thermo-refractive (PTR) glass with absolute diffraction efficiency ranging from greater than approximately 50% up to greater than approximately 93% and total losses below 5%. Both transmitting and reflecting volume diffractive elements were done from PTR glasses because of high spatial resolution enabling recording spatial frequencies up to 10000 mm . The use of such diffractive elements as angular selector, spatial filter, attenuator, switcher, modulator, beam splitter, beam sampler, beam deflectors controlled by positioning of grating matrix, by a small-angle master deflector or by spectral scanning, selector of particular wavelengths (notch filter, add/drop element, spectral shape former (gain equalizer), spectral sensor (wavelength meter/wavelocker), angular sensor (pointing locker), Bragg spectrometer (spectral analyzer), transversal and longitudinal mode selector in laser resonator were described. Combinations of those elements in the same volume are available too.

High efficiency volume diffractive elements in photo-thermo-refractive glass

A novel process is proposed for the volume diffractive element (Bragg grating) fabrication in photosensitive silicate glasses doped with silver, cerium, fluorine, and bromine. The process employs a photo-thermo-refractive (PTR) glass of high purity exposed to ultraviolet (UV) radiation of a He&mdash;Cd laser at 325 nm followed by thermal development at temperatures from 480&deg; C. to 580&deg; C., preferably at 520&deg; C., from several minutes to several hours. Absolute diffraction efficiency up to 95% was observed for 1 mm thick gratings. Maximum spatial frequency recorded in PTR glass was about of 10,000 mm . No decreasing of diffraction efficiency were detected at low spatial frequencies. Original glasses were transparent (absorption coefficient less than 1 cm ) from 350 to 4100 nm. Induced losses in exposed and developed glass decreased from 0.3 to 0.03 cm between 400 and 700 nm, respectively, and did not exceed 0.01-0.02 cm in the infrared (IR) region from 700 to 2500 nm.

Process for production of high efficiency volume diffractive elements in photo-thermo-refractive glass

An apparatus and method for physically separating non-metallic substrates forms a microcrack in the substrate and controllingly propagates the microcrack. An initial mechanical or pulsed laser scribing device forms a microcrack in the substrate. If a pulsed laser is used, it forms a crack inside the substrate that does not extend to either the upper or lower surface. A scribe beam is applied onto the substrate on a separation line. A coolant stream intersects with, or is adjacent to, the trailing edge of the scribe beam. The temperature differential between the heat affected zone of the substrate and the coolant stream propagates the microcrack. Two breaking beams on opposing sides of the separation line follow the coolant stream. The breaking beams create controlled tensile forces that extend the crack to the bottom surface of the substrate for full separation. The scribe and break beams and coolant stream are simultaneously moved relative to the substrate. A preheat beam preheats the heat affected area on the substrate. The beams are formed by an arrangement of lasers and mirrors and lenses. A movable mirror selectively diverts a beam to form either the preheat beam or one or more of the break and scribe beams. Spherical aberration is introduced in the break and scribe beams to flatten their energy distribution profiles and evenly apply the beam energy.

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Orlando, FL, United States of America

Leonid B Glebov