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.

Electrically tunable efficient broad-band fiber filter

Abstract: We demonstrate a new type of fiber-optic electrically tunable filter that enables a tuning range of 60 mm with an electrical power of 0.17 W, corresponding to a tuning efficiency of approximately 320 nm/W. The device is based on a metal coated long-period fiber grating written in a specially designed "air-clad" fiber that is filled with a polymer whose index of refraction is a sensitive function of temperature. Resistive heating, caused by current flowing through the metal coating, heats the polymer and induces changes in its index of refraction; these changes induce shifts in the position of the attenuation dip associated with the long-period grating. The air-clad structure has two benefits: (1) it enables the introduction of temperature sensitive materials into the fiber thus enabling power efficient operation of the device and (2) ensures that the cladding modes are insensitive to the surrounding environment and thus are unaffected by the metal coating on the surface of the fiber.

Analysis of grating surface emitting lasers

Abstract: An approach to the analysis of grating-coupled semiconductor lasers is presented. It is shown that there are only two resonant solutions when the grating has infinite extent. The solutions are either symmetric or antisymmetric about the center of the longitudinal coordinate system where the antisymmetric solution is nonradiating. The field in the grating layer is expressed in terms of grating eigenfunctions and rigorously matched to the boundary conditions at the waveguide interface. Solutions to the finite-length grating problem are expressed as linear combinations of the infinite-length solutions. It is shown that the two diffraction parameters in the coupled-wave equations are composed of sums and differences of the eigenvalues from the infinite-length problem. >

32×32 arrayed-waveguide grating multiplexer with uniform loss and cyclic frequency characteristics

Abstract: A 32/spl times/32 arrayed-waveguide grating multiplexer with uniform-loss and cyclic-frequency characteristics has been fabricated on a silica-based planar lightwave circuit. The device consists of an 80-channel arrayed-waveguide multiplexer with 100 GHz spacing and 32 optical combiners which are connected to the 72 output waveguides of the multiplexer. The peak-to-peak loss and channel centre frequency variations are 1.2 dB and 22.3 GHz, respectively, for entire 32/spl times/32 input/output combinations. These values have been substantially improved from conventional arrayed-waveguide multiplexers with peak-to-peak loss and centre frequency variations of 4.7 dB and 75.6 GHz respectively.

Method and an apparatus for measuring a displacement between two objects and a method and an apparatus for measuring a gap distance between two objects

Abstract: A method and an apparatus for measuring a displacement between two objects. Corresponding pairs of regions of the two objects each have at least one diffraction grating which generate two-dimensionally distributed diffracted light beams. These light beams are diffracted and caused to interfere with each other in the paired regions, whereby two-dimensionally distributed diffracted interference light beams are emitted. A light beam of a specific order is detected from each of these diffracted interference light beams, and is converted into a beat signal. The displacement is obtained in accordance with the phase difference between these beat signals.

Efficient grating-tuned mid-infrared Cr2+:CdSe laser.

Abstract: Room-temperature, all-solid-state, broadly tunable laser operation of Cr2+-doped CdSe has been demonstrated. Pumping with a Q-switched Tm, Ho:YLF laser running at a 1-kHz repetition rate achieved broadband output of 500 mW at 2.6 µm with 48% absorbed power slope efficiency. With reduced efficiency, as much as 815 mW of power was obtained. With a diffraction grating, the Cr2+:CdSe laser was tuned from 2.3 to 2.9 µm with 10-nm bandwidth (FWHM) and output power up to 350 mW.