Photonics

Reactive Solders Improve Fiber Couplers and OE Bonding

Optical and optoelectronic (OE) devices are being rapidly integrated into many facets of everyday life. From telecommunications to sensor applications, these devices are expected to perform accurately and reliably for long periods of time.

Posted in: ptb catchall, Applications, Photonics, Application Briefs

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Recirculation of Laser Power in an Atomic Fountain

Optical and electronic subsystems of a frequency standard can be simplified. NASA’s Jet Propulsion Laboratory, Pasadena, California A new technique for laser-cooling atoms in a cesium atomic fountain frequency standard relies on recirculation of laser light through the atom-collection region of the fountain. The recirculation, accomplished by means of reflections from multiple fixed beam-splitter cubes, is such that each of two laser beams makes three passes. As described below, this recirculation scheme offers several advantages over prior designs, including simplification of the laser system, greater optical power throughput, fewer optical and electrical connections, and simplification of beam power balancing.

Posted in: Tech Briefs, ptb catchall, Photonics, Briefs

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Simplified Generation of High-Angular-Momentum Light Beams

Inherent properties of a WGM resonator and optical fiber are exploited. NASA’s Jet Propulsion Laboratory, Pasadena, California A simplified method of generating a beam of light having a relatively high value of angular momentum (see figure) involves the use of a compact apparatus consisting mainly of a laser, a whispering-gallery-mode (WGM) resonator, and optical fibers. The method also can be used to generate a Bessel beam. (“Bessel beam” denotes a member of a class of non-diffracting beams, so named because their amplitudes are proportional to Bessel functions of the radii from their central axes. High-order Bessel beams can have high values of angular momentum.)

Posted in: Tech Briefs, ptb catchall, Photonics, Briefs

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Complex Type-II Interband Cascade MQW Photodetectors

Multiple active subregions, each optimized for a different color, would enable multicolor operation. NASA’s Jet Propulsion Laboratory, Pasadena, California Multiple-quantum-well (MQW) photodetectors of a proposed type would contain active regions comprising multiple superlattice subregions. These devices would have complex structures: The superlattice of each subregion would be designed for enhanced absorption of photons in a desired wavelength band (typically in the infrared) and multiple subregions of different design would be cascaded for multicolor operation.

Posted in: Tech Briefs, ptb catchall, Photonics, Briefs

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Interferometric Quantum-Nondemolition Single-Photon Detectors

These detectors would function independently of frequency. NASA’s Jet Propulsion Laboratory, Pasadena, California Two interferometric quantum-nondemolition (QND) devices have been proposed: (1) a polarization-independent device and (2) a polarization-preserving device. The prolarization-independent device works on an input state of up to two photons, whereas the polarization-preserving device works on a superposition of vacuum and single-photon states. The overall function of the device would be to probabilistically generate a unique detector output only when its input electromagnetic mode was populated by a single photon, in which case its output mode would also be populated by a single photon.

Posted in: Tech Briefs, ptb catchall, Photonics, Briefs

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Ring-Down Spectroscopy for Characterizing a CW Raman Laser

Parameters of operation can be obtained from a single ring-down scan. NASA’s Jet Propulsion Laboratory, Pasadena, California A relatively simple technique for characterizing an all-resonant intracavity continuous- wave (CW) solid-state Raman laser involves the use of ring-down spectroscopy. As used here, “characterizing” signifies determining such parameters as threshold pump power, Raman gain, conversion efficiency, and quality factors (Q values) of the pump and Stokes cavity modes.

Posted in: Tech Briefs, ptb catchall, Photonics, Briefs

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Digital Servos, Software Chart New Directions in Optical Scanning

Optical scanners, or servo-controlled, limited-rotation motors with laser-beam steering mirrors, were first introduced 40 years ago by General Scanning. Since then, they have become the enabling technology behind many innovative products across many different industries, including medical imaging, industrial machining, product identification, biomedical research, automotive manufacturing, and many more.

Posted in: Features, ptb catchall, Photonics, Articles

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