Diffraction grating

About: Diffraction grating is a research topic. Over the lifetime, 24884 publications have been published within this topic receiving 372437 citations. The topic is also known as: grating.

Trapping of surface plasmon waves in graded grating waveguide system

Abstract: We have proposed a graded grating plasmonic system with a significant slow-light effect for the propagation of high-confinement surface plasmon (SP) wave. Theoretical analysis and numerical simulations show that the localized position of SP wave in the plasmonic waveguide is dependent on the operating frequency. It is found that the slow-light effect exhibits an obvious enhancement with propagation. The proposed ultracompact configuration offers the advantage of a large trapping bandwidth of 90 THz, which may find excellent applications on slow-light systems, especially optical buffers.

Picosecond holographic grating generation of ultrasonic waves

Abstract: The picosecond holographic grating generation and detection of ultrasonic waves are described. Two mechanisms, a heating mechanism and a stimulated Brillouin scattering mechanism, are described. These permit the generation of tunable ultrasonic waves in the MHz to GHz range. It is demonstrated that the two mechanisms can be distinguished by the distinct time dependences of the diffraction of a variably delayed probe pulse from the acoustic gratings. In addition, the acoustic waves can be optically manipulated, i.e., amplified, cancelled, and phase shifted. The use of the technique for the detection of weak ground state absorptions and excited state-excited state absorptions is illustrated. Mixed excited state and acoustic gratings are discussed. The phase grating contribution to diffraction from an excited state grating is displayed, and the interference between the acoustic phase grating and the excited state phase grating is described and experimentally illustrated. Contributions to the acoustic grating diffraction from spectral shifts when the probe is near a strong, narrow transition are considered. Grating experiments on various phases of liquid crystal thin films are presented. It is shown that in addition to an acoustic grating, a Kerr effect grating is produced. The Kerr grating can be separated from the acoustic grating using polarization grating excitation. The Kerr grating reveals nonexponential relaxation of orientation order in liquid crystals on a short time scale (<1 ns).

Orotron&#8212;An electronic oscillator with an open resonator and reflecting grating

Abstract: The results are presented from a study of the orotron, a new electronic generator of the millimeter and submillimeter wavebands with a wide range of frequency tuning. An open resonator with a grating on one of its mirrors is used as the oscillatory system. The device is excited by passing an electron beam over the grating.

Semiconductor laser device

Abstract: PURPOSE:To manufacture a semiconductor laser for dynamic-single-longitudinal mode oscillations having optical wave guides of low loss which are suitable for integration by providing two channels of optical waveguide layers which are combined optically by diffraction gratings and performing current injection from a transverse direction to an active layer. CONSTITUTION:At least the 1st and 2nd optical waveguides 2 and 5 which are used for emitting light and for combining optically with an active layer 4 respectively are provided and both of them are combined optically by diffraction gratings 21 and 22 in which their degree are high, i.e., more than second order. In a dynamic-single-longitudinal mode oscillation laser that is manufactured in this way, carriers are injected horizontally from a transverse direction to the active layer 4 and then the carriers combine each other again in an active waveguide to emit light. Distributed feedback of light emitted is performed by the diffraction gratings of the 2nd optical waveguides 5 and its light combines optically with the 1st optical waveguide 2. Then it is induced and emitted in an active region by being reflected in the form of distribution. The waveguides of oscillating light become uniform and even when amplitude modulation takes place, they may oscillate at a stable, dynamic-single-mode.

Embossed diffraction grating alone and in combination with changeable image display

Abstract: A static diffracting grating display system provides a fixed image representing high digital content information. A plurality of physical diffracting features are fixed into the surface of a substrate. The diffracting features are positioned and oriented to selectively diffract or reflect a first incident beam of light which is then collected by a first display optical system. For color, preferably three light sources, red, green and blue, are used to form three incident beams of light. The period between adjacent ones of the diffracting features can be adjusted to appropriately form full-color image from the collected light. Preferably the diffracting features are formed by embossing a deformable substrate. Where the material of the deformable substrate is not reflective, a reflective coating is then applied. In some circumstances a protective overcoat applied over the reflective surface to obviate scratches or other damage to the diffracting features of the embossed surface. The diffracting features can also be formed using photolithographic techniques. To display changeable information in the image, a selectively deformable diffraction grating light valve is provided. A second incident beam of light is provided to illuminate the deformable diffraction grating light valve. A second display optical system collects light from the deformable diffraction grating light valve and merges this light with that collected from the static diffracting grating display system to form a unitary display.