Near-field radiation allows heat to propagate across a small vacuum gap at rates several orders of magnitude above that of far-field, blackbody radiation. Although heat transfer via near-field ...effects has been discussed for many years, experimental verification of this theory has been very limited. We have measured the heat transfer between two macroscopic sapphire plates, finding an increase in agreement with expectations from theory. These experiments, conducted near 300 K, have measured the heat transfer as a function of separation over mm to μm and as a function of temperature differences between 2.5 and 30 K. The experiments demonstrate that evanescence can be put to work to transfer heat from an object without actually touching it.
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Advanced LIGO (aLIGO) requires multiple frequency sidebands to disentangle all of the main interferometer's length signals. This paper presents the results of a risk reduction experiment to produce ...two sets of frequency sidebands in parallel, avoiding mixed 'sidebands on sidebands'. Two phase modulation frequencies are applied to separate Electro-Optic Modulators (EOMs), with one EOM in each of the two arms of a Mach-Zehnder interferometer. In this system the Mach-Zehnder's arm lengths are stabilized to reduce relative intensity noise in the recombined carrier beam by feeding a corrective control signal back to the Rubidium Titanyl Phosphate (RTP) EOM crystals to drive the optical path length difference to zero. This setup's use of the RTP crystals as length actuators provides enough bandwidth in the feedback to meet arm length stability requirements for aLIGO.
Diffraction gratings affect the absolute phase of light in a way that is not obvious from the usual derivation of optical paths using the grating equation. For example, consider light which ...encounters first one and then the second of two parallel gratings. If one grating is moved parallel to its surface, the phase of the light diffracted from the grating pair is shifted by 2pi each time the grating is moved by one grating constant, even though the geometric path length is not altered by the motion. This additional phase shift must be included when incorporating diffraction gratings in interferometers.
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We have shown that pump light intensity stabilisation of a single-mode laser diode pumped Nd:YAG non-planar ring oscillator (NPRO) results in significant intensity noise reduction of the NPRO, as ...well as frequency noise suppression in the same order of magnitude. This effect does not occur in conventional laser diode array pumped NPROs due to mode beating effects originating in the multi-mode pump. As opposed to individual intensity and frequency stabilisation, pump light stabilisation contributes a simplified stabilisation scheme for single-mode laser diode pumped NPROs for high precision applications.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We report on 50% conversion efficiency for frequency doubling of a 854 nm GaAlAs diode laser using a potassium niobate crystal in an external ring cavity. Frequency stabilization of the diode laser ...is achieved by direct optical feedback from the doubling cavity or from a grating in Littrow configuration. We determine 200 kHz linewidth from the measured spectral density of the frequency noise and from a beat signal measurement of two independent diode lasers. The blue output power of 7.8 mW shows rms-fluctuations of less than 0.6% in 1 MHz bandwidth.
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IJS, IMTLJ, KILJ, KISLJ, NUK, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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