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-programmable optical processor with enhanced resolution

Abstract: An optical apparatus is disclosed for processing light that based on a pair of diffraction gratings operating in tandem, with one of the gratings being a fixed diffraction grating and with the other grating being electrically programmable. The combination of the fixed and electrically-programmable diffraction gratings provides a spectral resolution and dispersion higher than that of either diffraction grating when used alone. These two diffraction gratings can be formed on different substrates, or alternately be combined to form a composite diffraction grating. The electrically-programmable diffraction grating can be operated in either a singly-periodic mode or a multi-periodic mode to select particular wavelengths of the incident light for analysis and detection, or for transferring between optical fibers (e.g. wavelength division multiplexing or demultiplexing). In some cases, a prism can be substituted for the fixed diffraction grating or used in addition to the fixed grating. The optical apparatus has applications for use in remote spectral analysis, spectrometry, and optical fiber communications.

High 90% efficiency Bragg gratings formed in fused silica by femtosecond Gauss-Bessel laser beams

Abstract: Direct laser write of volume Bragg gratings with diffraction efficiency (absolute) ∼90% is demonstrated using Gauss-Bessel laser beams in fused silica glass. Axial multiplexing of ∼ 90 μm long segments of modified optical material was demonstrated and thick Bragg gratings of aspect ratio depth/period ≈234 were achieved with period d = 1.5 μm. Typical fabrication scanning speeds were up to 50 mm/s for gratings with cross sections up to five millimeters made within 1 h time. Potential applications of high efficiency Bragg gratings in a low nonlinearity medium such as silica are discussed.

Optical system with aberration suppression and optical head utilizing the same

Abstract: An optical system, that includes a light source having sufficient coherency to provide a predominate operating wavelength and a diffraction grating lens system to focus the light from the light source to an image point on the optical axis of the optical system, provides for change of position of the image point along the optical axis over a wide focusing range with suppression of generated aberration. In particular, the optical system comprises a light source both movable in the direction of the optical axis and capable of variation in wavelength and a diffraction grating lens system that condenses the beam from the light source onto an image point on and along the optical axis, which system is effective in cancelling out aberration generated due to movement of the light source. The spherical aberration associated with the movement of the image spot brought about by the movement of the light source or its equivalent in the optical system is cancelled out by the chromatic aberration generated by the diffraction grating created by adjustment the light source wavelength.

Multiple wavelength operation of an erbium-doped fiber laser

Abstract: Wavelength-locked, six-channel, colasing operation using a single gain medium is reported for the first time. The system is an all-fiber, erbium-amplifier-based design that uses a grating wavelength division multiplexer with a fixed channel spacing of 4.8 nm for frequency selection. The authors investigate two possible configurations for the laser cavity. >

Cost-effective CMOS-compatible grating couplers with backside metal mirror and 69% coupling efficiency.

Abstract: A highly efficient grating structure for the coupling between standard optical fibers and single-mode waveguides in the silicon-on-insulator platform realized in a CMOS fabrication process is presented. The cost-effective method introduces a backside metal mirror to the grating coupler without need of an extensive wafer-to-wafer bonding. A coupling efficiency of −1.6 dB (around 69%) near the telecommunication wavelength 1550 nm and a large 1dB-bandwidth of 48 nm are achieved.