Photonics

Delaying Trains of Short Light Pulses in WGM Resonators

Delays would not be limited by resonator ring-down times. NASA’s Jet Propulsion Laboratory, Pasadena, California Suitably configured whispering-gallery-mode (WGM) optical resonators have been proposed as delay lines for trains of short light pulses. Until now, it has been common practice to implement an optical delay line as a coiled long optical fiber, which is bulky and tends to be noisy. An alternative has been to implement an optical delay line as a coupled-resonator optical wave-guide (a chain of coupled optical resonators), which is compact but limits the width of the pulse spectrum to the width of an optical resonance and thereby places a lower limit on the duration of a pulse. In contrast, a delay line according to the proposal could be implemented as a single WGM resonator, and the pulses delayed by the resonator could be so short that their spectral widths could greatly exceed the spectral width of any single resonance.

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

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Creating Patterned Multispectral Filters

In recent years the explosion in demand for multispectral imaging has coupled with the industry’s insatiable need for weight reduction, there-by greatly increasing the demand for more sophisticated approaches to producing optical filters that are used in these systems. One method to meet the challenge of reducing the weight of a multispectral system is to eliminate beam-splitting optics and multiple detectors by patterning a filter array on a single substrate, or directly on the CCD itself.

Posted in: Features, ptb catchall, Photonics, Articles

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Implementing Thermal Bumps in New Product Designs

Thermal issues are dominating today’s electronic product design landscape as never before. It is easy to see this in Intel’s move to a multi-core architecture as a methodology to manage their thermal problems. Of course, less than optimal solutions lead to less than optimal results. Thermoelectric devices (TECs) have been used in the optoelectronics industry for thermal management, but have not found wide-spread acceptance in electronic product design. Thermal management solutions implemented with these active devices, however, offer a broad potential for implementation including the following:

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

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NbxTi1–xN Superconducting-Nanowire Single-Photon Detectors

Potential applications include optical communications and quantum cryptography. NASA’s Jet Propulsion Laboratory, Pasadena, California Superconducting-nanowire single-photon detectors (SNSPDs) in which NbxTi1–xN (where xerve as the superconducting materials have shown promise as superior alternatives to previously developed SNSPDs in which NbN films serve as the superconducting materials. SNSPDs have potential utility in optical communications and quantum cryptography.

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Miniature Incandescent Lamps as Fiber-Optic Light Sources

These lamps can be used without coupling optics. John H. Glenn Research Center, Cleveland, Ohio Miniature incandescent lamps of a special type have been invented to satisfy a need for compact, rapid-response, rugged, broadband, power-efficient, fiber-optic-coupled light sources for diverse purposes that could include calibrating spectrometers, interrogating optical sensors, spot illumination, and spot heating. A lamp of this type (see figure) includes a re-entrant planar spiral filament mounted within a ceramic package heretofore normally used to house an integrated-circuit chip. The package is closed with a window heretofore normally used in ultraviolet illumination to erase volatile electronic memories. The size and shape of the filament and the proximity of the filament to the window are such that light emitted by the filament can be coupled efficiently to an optical fiber without intervening optics.

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Prism Window for Optical Alignment

Prism windows could be generally useful in manufacture of optical instruments. NASA’s Jet Propulsion Laboratory, Pasadena, California A prism window has been devised for use, with an autocollimator, in aligning optical components that are (1) required to be oriented parallel to each other and/or at a specified angle of incidence with respect to a common optical path and (2) mounted at different positions along the common optical path. The prism window can also be used to align a single optical component at a specified angle of incidence. Prism windows could be generally useful for orienting optical components in manufacture of optical instruments.

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Range-Gated Metrology With Compact Optical Head

A compact, single-fiber optical head requires minimal internal alignment. NASA’s Jet Propulsion Laboratory, Pasadena, California This work represents a radical simplification in the design of the optical head needed for high-precision laser ranging applications. The optical head is now a single fiber-optic collimator with dimensions of order of 1×1×2 cm, which can be easily integrated into the system being measured with minimal footprint. Previous heads were significantly larger, with multiple optical elements requiring careful alignment. The new design has only one optical fiber per head, rather than four, making it much easier to multiplex between tens or hundreds of heads. It is capable of subnanometer precision, consistent with the demanding requirements of new missions.

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

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