Photonics

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.

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

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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.

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

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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.

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

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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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Performance of 1mm² Silicon Photomultipliers

A silicon photomultiplier (SPM) is a new type of semiconductor detector that has the potential to replace the photomultiplier tube (PMT) detector in many applications. In common with a PMT detector, the output of an SPM is an easily detectable current pulse for each detected photon and can be used in both photon counting mode and as an analogue (photocurrent) detector. However, the SPM also has a distinct advantage over PMT detectors. The photon-induced current pulse from a PMT varies greatly from photon to photon, due to the statistics of the PMT multiplication process (excess noise). In contrast, the current pulse from an SPM is identical from photon to photon. This gives the SPM a distinct advantage in photon counting applications as it allows the associated electronics to be greatly simplified. Identical pulses also mean that the SPM can resolve the number of photons in weak optical pulses, so-called photon number resolution. This is critical in a number of applications including linear-optics quantum computing.

Posted in: Features, ptb catchall, Photonics, Articles

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