63 results about "Crystal optics" patented technology

A system for generating signals for Raman vibrational analysis, particularly for a CARS microscope or spectroscope of an external specimen, the system comprising a a laser source apt to emit at least one fundamental optical pulse in a first band of fundamental frequencies comprising at least one first (ω_f1) and one second (ω_f2) fundamental frequencies; a second-harmonic (SH) generating system comprising at least one nonlinear optical crystal for converting said at least one fundamental optical pulse into at least two second-harmonic optical pulses, i.e. a first second-harmonic pulse at a first second-harmonic frequency (ω_p) of the first fundamental frequency (ω_f1) and a second second-harmonic pulse at a second second-harmonic frequency (ω_s) of the second fundamental frequency (ω_f2), said second second-harmonic frequency being other than the first second-harmonic frequency, and a Raman vibrational analysis apparatus apt to receive said first and second second-harmonic pulses and direct them toward said specimen.

According to an embodiment, the SH system comprises two nonlinear optical crystals, each including a ferroelectric crystal with periodic space-modulation of the sign of the optical susceptibility.

In a different embodiment, the SH system comprises a ferroelectric crystal with aperiodic space-modulation of the sign of nonlinear optical susceptibility, with a period varying along the optical path of said at least one fundamental optical pulse, said crystal being apt to generate said first and second second-harmonic pulses.

Compact, low-power-consuming systems and methods for exposing samples to high-energy radiation, for example, for exposing samples to x-rays for implementing x-ray absorption near edge analysis (XANES). The systems and methods include a low-power-consuming radiation source, such as an x-ray tube; one or more tunable crystal optics for directing and varying the energy of the radiation onto a sample under analysis; and a radiation detecting device, such as an x-ray detector, for detecting radiation emitted by the sample. The one or more tunable crystal optics may be doubly-curved crystal optics. The components of the system may be arranged in a collinear fashion. The disclosed systems and methods are particularly applicable to XANES analysis, for example, XANES analysis of the chemical state of chromium or another transition metal in biological processes.

The present invention provides a method for fast switching of optical properties in photonic crystals using pulsed/modulated free-carrier injection. The results disclosed herein indicate that several types of photonic crystal devices can be designed in which free carriers are used to vary dispersion curves, stop gaps in materials with photonic bandgaps to vary the bandgaps, reflection, transmission, absorption, gain, or phase. The use of pulsed free carrier injection to control the properties of photonic crystals on fast timescales forms the basis for all-optical switching using photonic crystals. Ultrafast switching of the band edge of a two-dimensional silicon photonic crystal is demonstrated near a wavelength of 1.9 μm. Changes in the refractive index are optically induced by injecting free carriers with 800 nm, 300 fs pulses. Band-edge shifts have been induced in silicon photonic crystals of up to 29 nm that occurs on the time-scale of the pump pulse. The present invention also provides a method of producing a virtual or temporary photonic crystal using free carrier injection into pure semiconductors, bulk or thin film, in which the carriers are generated in patterns which create a patterned refractive index contrast used to steer light beams in the semiconductor while it is being pulsed.

Provided is a projection type liquid crystal display apparatus, which can improve black-level display and thus can display a higher-contrast image as compared to the related art. An optical compensator is located on the light exit side with respect to the liquid crystal display device so as to compensate for the optical phase difference caused by liquid crystal molecules in a light-entry-side region of the liquid crystal layer. As the optical compensator is located on the light exit side with respect to the liquid crystal display device, birefringence, caused by the liquid crystal molecules present in the light-entry-side region, is compensated for without being influenced by a microlenses provided in the liquid crystal plane. Consequently, the apparatus can improve the black-level display and thus can display a higher-contrast image as compared to the related art. Further, a phase difference caused by the birefringence of the nematic liquid crystal molecule is compensated for by using a substance having properties optically opposite to the positive crystal, namely, a substance having birefringence equivalent to birefringence of a negative crystal.

The invention relates to a two-dimensional photonic-crystal optical router based on a nested ring cavity structure. A two-dimensional photonic crystal, which is a triangular lattice medium column structure, is formed by one ring cavity including one large non-equilateral hexagon and one small non-equilateral hexagon which are nested, wherein the ring-shaped cavity is guided in two horizontal input and output waveguides. Several medium columns are distributed in the ring cavity in a central symmetry mode, and the whole structure is distributed symmetrically. An appropriate structure parameter is selected. The router can simultaneously realize forward bottom route and backward bottom route functions of a single wavelength input light wave, the forward bottom route and backward bottom route functions of two wavelength input light waves, and a function of exchanging forward and backward bottom route directions of two wavelengths. Compared to the two-dimensional photonic-crystal optical router of a single ring cavity structure, by using the router of the invention, a bottom route effect is obviously increased and can reach 100%. The router possesses characteristics that the structure is simple; manufacturing is easy; a size is small; cost is low; stability is high; and flexible functions are possessed and so on. The router can be mainly applied to an all-optical integrated loop network.

The present invention has been devised to provide a two-dimensional photonic crystal optical resonator and optical reflector having high light-extracting efficiency. This is achieved by the following construction. A two-dimensional photonic crystal consisting of a slab-shaped body 11 is created by periodically arranging areas (or holes) 12 having a refractive index different from that of the body 11. A waveguide 13 is formed by providing a linear zone where no hole 12 is bored. Two acceptor type point defects 14 are formed by enlarging two holes 12 spaced apart from each other by a distance L in the longitudinal direction of the waveguide. In this construction, an appropriate selection of the distance L suppresses the reflection and transmission of light at the point defects 14, allowing an efficient extraction of light resonating at the point defects 14. An appropriate selection of the distance L will increase the reflectivity of light at the point defects 14. This allows the body 11 to be used as an optical resonator for producing a resonance of light between the two point defects 14 or an optical reflector for reflecting light at the two point defects 14.

An object of the present invention is to provide a comparatively small-scale device, that is a second harmonic generating device of a laser beam with which high-quality and large output light is obtained efficiently and stably. Specifically, the second harmonic generating device of a laser beam source includes a laser beam source, an optical resonator into which the said laser beam is injected, and KTP crystals provided in the said optical resonator. The KTP crystals in the optical resonator are a first a-axis-cut KTP crystal in which a beam of light carries out a-axis propagation and a second a-axis-cut KTP crystal, which is the same length as the first a-axis-cut KTP crystal and is rotated 90 degrees on the a-axis with respect to the first a-axis-cut KTP crystal.

The invention provides a preparation method for a three-dimensional crystal optics echo wall micro-cavity. The preparation method comprises the steps: carrying out femtosecond laser selective ablation on crystals soaked in liquid and grinding the lateral wall of the micro-cavity by using a focused ion beam. The three-dimensional crystal optics echo wall micro-cavity prepared by adopting the method provided by the invention can be used for limiting light through continuous total internal reflection of the cavity and an outside face, and has the advantages of extremely high surface smoothness, small mode volume and high quality factor. The preparation method is applicable to various crystal materials, glass and the like.

The invention relates to a trapezoidal structure based crystal optical electric field sensor, belonging to the technical field of electric field measurement. The electric field sensor comprises a crystal, a polarizer and a polarization analyzer, wherein one end part of the crystal is trapezoidal while the other end part of the crystal is rectangular; the polarizer is stuck to a laser incidence place of the rectangular end part of the crystal; the polarization analyzer is stuck to a laser emission place of the rectangular end part of the crystal; and a top angle a of the trapezoidal end part of the crystal and optical polarization points of the electric field sensor satisfy a certain relationship. Three total reflection of the end face of the electro-optical crystal is utilized to generate optical polarization points, and a special trapezoidal top angle is selected to remove 1/4 wave plate of the optical polarization points, so that the trapezoidal structure based crystal optical electric field sensor, disclosed by the invention, has the advantages of simplifying a sensor structure and improving temperature stability of the sensor. The optical electric field sensor, disclosed by the invention, has the advantages of not only measuring the amplitude value of the electric field, but also measuring information such as frequency and phase position of the electric field, and is a time domain electric field sensor.

Increased yield of optical elements from cubic crystal rods, such as made of calcium fluoride, is made possible by orienting the optical elements for supporting the propagation of light along one of the <1 1 {overscore (2)}>, <1 2 1>, or <{overscore (2)} 1 1> alternative crystal axis, which extend perpendicular to a main <1 1 1> crystal axis. A cleave is taken through the crystal rod along a primary crystal plane {1 1 1} normal to the <1 1 1> main axis. One of the <1 1 {overscore (2)}>, <1 {overscore (2)} 1>, or <{overscore (2)} 1 1> alternative crystal axes is located by optical inspection and indicated on the crystal rod with an orientation label. Additional cuts are taken parallel to the {1 1 1} primary crystal plane to divide the crystal rod into disks each containing a portion of the orientation label. The disks can be cut again and sides formed perpendicular to the {1 1 1} primary crystal plane with regard to the orientation labels for forming optical elements, such as prisms, oriented for supporting the propagation of polarized light along one of the <1 1 {overscore (2)}>, <1 {overscore (2)} 1>, and <{overscore (2)} 1 1 > alternative crystal axes.

An optical system includes at least one cubic crystalline optical element aligned along an optical axis, the at least one cubic crystalline optical element being birefringent and imparting retardance on a beam of light propagating through the optical system along the optical axis, and polarization rotation optics inserted along the optical axis and selected to rotate the polarization of the beam of light to at least partially reduce the retardance.