Photonics

Optical Magnetometer Incorporating Photonic Crystals

Sensitivity would be increased by orders of magnitude. NASA’s Jet Propulsion Laboratory, Pasadena, California According to a proposal, photonic crystals would be used to greatly increase the sensitivities of optical magnetometers that are already regarded as ultrasensitive. The proposal applies, more specifically, to a state-of-the-art type of quantum coherent magnetometer that exploits the electromagnetically-induced-transparency (EIT) method for determining a small change in a magnetic field indirectly via measurement of the shift, induced by that change, in the hyperfine levels of resonant atoms exposed to the field.

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

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Raman-Suppressing Coupling for Optical Parametric Oscillator

Loading of desired modes is reduced, relative to loading of undesired modes. NASA’s Jet Propulsion Laboratory, Pasadena, California A Raman-scattering-suppressing input/output coupling scheme has been devised for a whispering-gallery-mode optical resonator that is used as a four-wave-mixing device to effect an all-optical parametric oscillator. Raman scattering is undesired in such a device because (1) it is a nonlinear process that competes with the desired nonlinear four-wave conversion process involved in optical parametric oscillation and (2) as such, it reduces the power of the desired oscillation and contributes to output noise.

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WGM-Resonator/Tapered-Waveguide White-Light Sensor Optics

Light patterns formed by these optics contain information on absorption spectra. NASA’s Jet Propulsion Laboratory, Pasadena, California Theoretical and experimental investigations have demonstrated the feasibility of compact white-light sensor optics consisting of unitary combinations of (1) low-profile whispering-gallery-mode (WGM) resonators and (2) tapered rod optical waveguides. These sensors are highly wavelength-dispersive and are expected to be especially useful in biochemical applications for measuring absorption spectra of liquids.

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Cold Atom Source Containing Multiple Magneto-Optical Traps

This source allows a smaller package relative to single-trap sources of similar performance. NASA’s Jet Propulsion Laboratory, Pasadena, California An apparatus that serves as a source of a cold beam of atoms contains multiple two-dimensional (2D) magneto-optical traps (MOTs). (Cold beams of atoms are used in atomic clocks and in diverse scientific experiments and applications.) The multiple-2D-MOT design of this cold atom source stands in contrast to single-2D-MOT designs of prior cold atom sources of the same type. The advantages afforded by the present design are that this apparatus is smaller than prior designs.

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Opto-Electronic Oscillator Using Suppressed Phase Modulation

Phase noise would be much lower than in prior OEOs. NASA’s Jet Propulsion Laboratory, Pasadena, California A proposed opto-electronic oscillator (OEO) would generate a microwave signal having degrees of frequency stability and spectral purity greater than those achieved in prior OEOs. The design of this system provides for reduction of noise levels (including the level of phase noise in the final output microwave signal) to below some of the fundamental limits of the prior OEOs while retaining the advantages of photonic generation of microwaves. Whereas prior OEOs utilize optical amplitude modulation, this system would utilize a combination of optical phase modulation and suppression thereof. The design promises to afford, in the opto-electronic domain, the low-noise advantages of suppression of carrier signals in all-electronic microwave oscillators.

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

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Alternative Controller for a Fiber-Optic Switch

This controller communicates via a serial instead of a parallel port. NASA’s Jet Propulsion Laboratory, Pasadena, California The figure is a simplified diagram of a relatively inexpensive controller for a DiCon VX (or equivalent) fiber-optic switch — an electromechanically actuated switch for optically connecting one or two input optical fibers to any of a number of output optical fibers. DiCon VX fiber-optic switches are used primarily in research and development in the telecommunication industry. This controller can control any such switch having up to 32 output channels.

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

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Hardware and Software for Air-to-Air Schlieren Imaging

Accurate positioning and camera control are necessary for success in schlieren imaging. Software and electronic hardware are being developed to provide cockpit guidance and camera control for an air-to-air schlieren photography system that is to be used to take high-resolution pictures of shock waves generated by a full-scale airplane (see Figure 1). For success in schlieren imaging, it will be necessary to position two airplanes — an observing airplane and the one generating the shock waves — precisely along a line of sight to the Sun, which will be used for illumination. The shock-wave-generating airplane will fly at supersonic speed, while the observing airplane will have to fly at a much lower speed of 250 knots (129 m/s).

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