Photonics

DPSS Micromachining Puts Shine on Industrial Molds

Modular diode-pumped solid state (DPSS) lasers make it easy to tailor laser sources to micromachining applications, such as steel and ceramic molds. Lasers are now used to micromachine virtually every type of material, including metals, plastics, glass, and ceramics. Micromachining is a highly diverse market that uses flash-pumped, diode-pumped solid-state (DPSS), and excimer lasers. Excimer lasers provide more average power at shorter wavelengths, enabling more precise micromachining, but as DPSS lasers have added increased average output power to their lower acquisition and operation costs, small footprint, improved mode operation, and high-repetition pulse rate, DPSS systems are grabbing a larger share of the micromachining market.

Posted in: Features, ptb catchall, Photonics, Articles

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Silicon Modulator Brings Optical Computing A Step Closer

This electrically driven, compact silicon modulator is based on a photonic crystal design. University of Texas at Austin and Omega Optics, Austin, Texas For decades, silicon has not been considered a favorable material for manipulating light. Electrical Engineering Professor Ray Chen at the University of Texas at Austin and Wei Jiang at Omega Optics in Austin recently developed an electrically driven, compact silicon modulator based on a photonic crystal design that offers significant performance improvements over existing Mach-Zehnder Interferometer (MZI)-based silicon modulators.

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

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Simulation Keeps Optical Transceiver Signals in Place

Electromagnetic analysis software helps designers avoid FCC and CE compliance pitfalls. Flomerics, Inc., Marlborough, Massachusetts Problems emerge when electromagnetically “hot” optical transceivers are placed into systems that are bound by emissions limits. Because radiating transceivers are mounted externally or couple to inherent features of systems such as air vents, seams, and holes, they break the integrity of the enclosure shield and cause these systems to behave like antennas, amplifying energy generated inside systems and then transmitting to the outside world.

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

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Quantum-Dot Laser for Wavelengths of 1.8 to 2.3 μm

Process conditions must be controlled to form quantum dots at sufficient density. NASA’s Jet Propulsion Laboratory, Pasadena, California The figure depicts a proposed semiconductor laser, based on In(As)Sb quantum dots on a (001) InP substrate, that would operate in the wavelength range between 1.8 and 2.3 μm. InSb and InAsSb are the smallest-bandgap conventional III-V semiconductor materials, and the present proposal is an attempt to exploit the small bandgaps by using InSb and InAsSb nanostructures as mid-infrared emitters.

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

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Tunable Filter Made From Three Coupled WGM Resonators

This is a prototype of high-performance filters for photonic applications. NASA’s Jet Propulsion Laboratory, Pasadena, California A tunable third-order band-pass optical filter has been constructed as an assembly of three coupled, tunable, whispering-gallery-mode resonators similar to the one described in “Whispering-Gallery-Mode Tunable Narrow-Band-Pass Filter” (NPO-30896), NASA Tech Briefs, Vol. 28, No. 4 (April 2004), page 5a. This filter offers a combination of four characteristics that are desirable for potential applications in photonics: (1) wide real-time tunability accompanied by a high-order filter function, (2) narrowness of the passband, (3) relatively low loss between input and output coupling optical fibers, and (4) a sparse spectrum. In contrast, prior tunable band-pass optical filters have exhibited, at most, two of these four characteristics.

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

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Dynamic Pupil Masking for Phasing Telescope Mirror Segments

Piston and tilt adjustments could be performed more efficiently. NASA’s Jet Propulsion Laboratory, Pasadena, California A method that would notably include dynamic pupil masking has been proposed as an enhanced version of a prior method of phasing the segments of a primary telescope mirror. The method would apply, more specifically, to a primary telescope mirror that comprises multiple segments mounted on actuators that can be used to tilt the segments and translate them along the nominal optical axis to affect wavefront control in increments as fine as a fraction of a wavelength of light. An apparatus (see figure) for implementing the proposed method would be denoted a dispersed-fringe-sensor phasing camera system (DPCS).

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

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Pattern-Recognition Algorithm for Locking Laser Frequency

NASA’s Jet Propulsion Laboratory, Pasadena, California A computer program serves as part of a feedback control system that locks the frequency of a laser to one of the spectral peaks of cesium atoms in an optical-absorption cell. The system analyzes a saturation absorption spectrum to find a target peak and commands a laser-frequency-control circuit to minimize an error signal representing the difference between the laser frequency and the target peak. The program implements an algorithm consisting of the following steps:

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

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