Showing papers by "Martin M. Fejer published in 2006"
TL;DR: The polar Kerr effect in the spin-triplet superconductor Sr2RuO4 was measured with high precision using a Sagnac interferometer with a zero-area Sagnacs loop, implying a broken time-reversal symmetry state in the superconducting state of Sr2 RuO4, similar to 3He-A.
Abstract: The polar Kerr effect in the spin-triplet superconductor Sr2RuO4 was measured with high precision using a Sagnac interferometer with a zero-area Sagnac loop We observed nonzero Kerr rotations as big as 65 nanorad appearing below Tc in large domains Our results imply a broken time-reversal symmetry state in the superconducting state of Sr2RuO4, similar to 3He-A
434 citations
TL;DR: Integrated structures that will allow for improvements of current signal-processing functions as well as the implementation of novel device concepts are presented.
Abstract: The authors present a review of all-optical signal-processing technologies based on /spl chi//sup (2)/ nonlinear interactions in guided-wave devices and their applications for telecommunication. In this study, the main focus is on three-wave interactions in annealed proton-exchanged periodically poled lithium niobate waveguides due to their suitable properties with respect to nonlinear mixing efficiency, propagation loss, and ease of fabrication. These devices allow the implementation of advanced all-optical signal-processing functions for next-generation networks with signal bandwidths beyond 1 THz. In this paper, integrated structures that will allow for improvements of current signal-processing functions as well as the implementation of novel device concepts are also presented.
246 citations
TL;DR: In this paper, an efficient room temperature source of terahertz radiation using femtosecond laser pulses as a pump and GaAs structures with periodically inverted crystalline orientation, such as diffusion-bonded stacked GaAs and epitaxially grown orientation-patterned GaAs, as a nonlinear optical medium was demonstrated.
Abstract: The authors demonstrate an efficient room temperature source of terahertz radiation using femtosecond laser pulses as a pump and GaAs structures with periodically inverted crystalline orientation, such as diffusion-bonded stacked GaAs and epitaxially grown orientation-patterned GaAs, as a nonlinear optical medium. By changing the GaAs orientation-reversal period (504–1277μm), or the pump wavelength (2–4.4μm), we were able to generate narrow-bandwidth (∼100GHz) terahertz wave packets, tunable between 0.9 and 3THz, with the optical-to-terahertz photon conversion efficiency of 3.3%.
149 citations
TL;DR: The next-generation interferometers are currently being designed, and the thermal noise in the mirrors will set the sensitivity over much of the usable bandwidth, so achieving higher sensitivity through lower mechanical loss coatings, while preserving the crucial optical and thermal properties is an area of active research.
Abstract: Gravitational waves are a prediction of Einstein's general theory of relativity. These waves are created by massive objects, like neutron stars or black holes, oscillating at speeds appreciable to the speed of light. The detectable effect on the Earth of these waves is extremely small, however, creating strains of the order of 10−21. There are a number of basic physics experiments around the world designed to detect these waves by using interferometers with very long arms, up to 4 km in length. The next-generation interferometers are currently being designed, and the thermal noise in the mirrors will set the sensitivity over much of the usable bandwidth. Thermal noise arising from mechanical loss in the optical coatings put on the mirrors will be a significant source of noise. Achieving higher sensitivity through lower mechanical loss coatings, while preserving the crucial optical and thermal properties, is an area of active research right now.
128 citations
TL;DR: It is demonstrated that the optical comb lines can exhibit instrument-limited, subhertz relative linewidths across the comb spectra from 1200 to 1720 nm with a residual integrated optical phase jitter of approximately 1 rad in a 60 mHz to 500 kHz bandwidth.
Abstract: We investigate the comb linewidths of self-referenced, fiber-laser-based frequency combs by measuring the heterodyne beat signal between two independent frequency combs that are phase locked to a common cw optical reference. We demonstrate that the optical comb lines can exhibit instrument-limited, subhertz relative linewidths across the comb spectra from 1200 to 1720 nm with a residual integrated optical phase jitter of ∼1 rad in a 60 mHz to 500 kHz bandwidth. The projected relative pulse timing jitter is ∼1 fs. This performance approaches that of Ti:sapphire frequency combs.
121 citations
TL;DR: An ultrabroad mid-infrared continuum is generated by using single-pass optical parametric generation (OPG) in orientation-patterned GaAs (OP-GaAs), and the slope efficiency near threshold was 51%, and the external conversion efficiency was as high as 15%.
Abstract: We have generated an ultrabroad mid-infrared continuum by using single-pass optical parametric generation (OPG) in orientation-patterned GaAs (OP-GaAs). The spectrum spans more than an octave, from 4.5 to 10.7 µm, measured 20 dB down from the peak. The 17.5 mm long, 0.5 mm thick, all-epitaxially-grown OP-GaAs sample with a 166.6-µm quasi-phase-matching period was pumped with 3.1-3.3 µm wavelength, 1 ps pulses up to 2 µJ in energy. The OPG threshold was observed at 55 nJ pump energy with the pump polarized along the [111] crystal direction. The slope efficiency near threshold was 51%, and the external conversion efficiency was as high as 15%.
110 citations
TL;DR: In this paper, the authors presented a quantum key distribution experiment in which keys that were secure against all individual eavesdropping attacks allowed by quantum mechanics were distributed over 100 km of optical fiber.
Abstract: We present a quantum key distribution experiment in which keys that were secure against all individual eavesdropping attacks allowed by quantum mechanics were distributed over 100 km of optical fiber. We implemented the differential phase shift quantum key distribution protocol and used low timing jitter 1.55 µm single-photon detectors based on frequency up-conversion in periodically poled lithium niobate waveguides and silicon avalanche photodiodes. Based on the security analysis of the protocol against general individual attacks, we generated secure keys at a practical rate of 166 bit/s over 100 km of fiber. The use of the low jitter detectors also increased the sifted key generation rate to 2 Mbit/s over 10 km of fiber.
108 citations
TL;DR: A linearly polarized, narrow-linewidth, diode-pumped, Yb-doped silica-fiber oscillator operating at 1150 nm was frequency doubled to produce 40 mW of 575 nm radiation.
Abstract: A linearly polarized, narrow-linewidth, diode-pumped, Yb-doped silica-fiber oscillator operating at 1150 nm was frequency doubled to produce 40 mW of 575 nm radiation. The oscillator generated 89 mW of cw linearly polarized output power and was tunable over 0.80 nm. The laser output was coupled to a periodically poled LiNbO3 waveguide that converted 67% of the coupled power to the yellow. The system was fully integrated, with no free-space optics, and had an overall optical-to-optical efficiency of 7.0% with respect to the incident diode-laser pump power.
100 citations
TL;DR: This work demonstrates second-harmonic generation from sub-micrometer-sized AlGaAs/AlxOy artificially birefringent waveguides and further enhanced the SHG using a waveguide-embedded cavity formed by dichroic mirrors.
Abstract: We demonstrate second-harmonic generation (SHG) from sub-micrometer-sized AlGaAs/AlxOy artificially birefringent waveguides. The normalized conversion efficiency is the highest ever reported. We further enhanced the SHG using a waveguide-embedded cavity formed by dichroic mirrors. Resonant enhancements as high as approximately 10x were observed. Such devices could be potentially used as highly efficient, ultracompact frequency converters in integrated photonic circuits.
92 citations
TL;DR: A new source of frequency-tunable THz wave packets based on parametric down-conversion process in orientation-patterned GaAs (OP-GaAs) that produces muW-level THz average powers at the repetition rate of 100 MHz is demonstrated.
Abstract: We demonstrate a new source of frequency-tunable THz wave packets based on parametric down-conversion process in orientation-patterned GaAs (OP-GaAs) that produces µW-level THz average powers at the repetition rate of 100 MHz. The OP-GaAs crystal is pumped by a compact all-fiber femtosecond laser operating at the wavelength of 2 µm. Such combination of fiber laser and OP-GaAs technologies promises a practical source of THz radiation which should be suitable for many applications including imaging and spectroscopy.
90 citations
TL;DR: In this paper, a search for gravitational waves from binary black hole inspirals in the data from the second science run of the LIGO interferometers was reported. But no events that could be identified as gravitational waves in the 385.6 hours of data that they searched.
Abstract: We report on a search for gravitational waves from binary black hole inspirals in the data from the second science run of the LIGO interferometers. The search focused on binary systems with component masses between 3 and 20M⊙. Optimally oriented binaries with distances up to 1 Mpc could be detected with efficiency of at least 90%. We found no events that could be identified as gravitational waves in the 385.6 hours of data that we searched.
TL;DR: The thermo-mechanical properties of silicon make it of significant interest as a possible material for mirror substrates and suspension elements for future long-baseline gravitational wave detectors as mentioned in this paper.
TL;DR: In this paper, a Sagnac interferometer with a zero-area SAGA loop for measuring the magneto-optic Kerr effect at cryogenic temperatures is described.
Abstract: The authors describe a geometry for a Sagnac interferometer with a zero-area Sagnac loop for measuring the magneto-optic Kerr effect at cryogenic temperatures. The apparatus is capable of measuring absolute Kerr rotation without any modulation of the magnetic state of the sample and is intrinsically immune to reciprocal effects such as linear birefringence and thermal fluctuations. A single strand of polarization-maintaining fiber is fed into a He-3 cryostat, eliminating the need for optical viewports. With an optical power of only 10μW, they demonstrate static Kerr measurements with a shot-noise-limited sensitivity of 1×10−7rad∕Hz down to 0.5K.
TL;DR: In this article, it was shown that the spectral changes witnessed in curved long-period fiber gratings are the result of changes in the cladding-mode profiles in a bent fiber.
Abstract: The wavelength-selective attenuation notches generated by UV-induced long-period fiber gratings (LPFGs) have been shown to shift in wavelength and change in depth if the LPFG is bent along a curved path. Additionally, the notches frequently appear to "split" into two when the LPFG is curved. These effects have successfully allowed the realization of bend-sensing devices. Publications to date have not yielded a satisfactory physical interpretation for the apparent mode splitting. In this paper, it is shown that the spectral changes witnessed in curved LPFGs are the result of changes in the cladding-mode profiles in a bent fiber. The modes of a curved three-layer optical fiber numerically were determined and these fields are used to show that the uniform UV-induced perturbation allows coupling between the fundamental core mode and both symmetric and antisymmetric cladding modes when the fiber is curved, whereas coupling to only symmetric modes is allowed in the straight fiber. Coupling to these new modes is at the origin of new attenuation notches, which have been misinterpreted so far as mode splitting. Published devices' attenuation-notch wavelength shifts, apparent splitting, and relative depths are all well described using these changes in cladding-mode profiles.
TL;DR: Several techniques to modulate the local amplitude of quasi-phase-matched (QPM) interactions in periodically poled lithium niobate waveguides are proposed and demonstrated and apodization is demonstrated by using each of these techniques.
Abstract: We propose several techniques to modulate the local amplitude of quasi-phase-matched (QPM) interactions in periodically poled lithium niobate waveguides and demonstrate apodization by using each of these techniques. When the hard edges are removed in the spatial profile of the nonlinear coupling, the sidelobes of the frequency tuning curves are suppressed by 13 dB or more, compared with a uniform grating, consistent with theoretical predictions. The sidelobe-suppressed gratings are useful for frequency conversion devices in optical communication systems to minimize interchannel cross talk, while the amplitude modulation techniques in general have potential uses in applications that require altering the tuning curve shapes.
TL;DR: The first quantum key distribution experiment implemented with a 10-GHz clock frequency with differential phase shift protocol is reported, and sifted keys are generated at a rate of 3.7 kbit/s over a 105 km fiber with a bit error rate of 9.7%.
Abstract: This paper reports the first quantum key distribution experiment implemented with a 10-GHz clock frequency. We used a 10-GHz actively mode-locked fiber laser as a source of short coherent pulses and single photon detectors based on frequency up-conversion in periodically poled lithium niobate waveguides. The use of short pulses and low-jitter upconversion detectors significantly reduced the bit errors caused by detector dark counts even after long-distance transmission of a weak coherent state pulse. We employed the differential phase shift quantum key distribution protocol, and generated sifted keys at a rate of 3.7 kbit/s over a 105 km fiber with a bit error rate of 9.7%.
TL;DR: A quantum key distribution experiment in which keys that were secure against all individual eavesdropping attacks allowed by quantum mechanics were distributed over 100 km of optical fiber using low timing jitter 1.55 microm single-photon detectors.
Abstract: We present a quantum key distribution experiment in which keys that were secure against all individual eavesdropping attacks allowed by quantum mechanics were distributed over 100 km of optical fiber. We implemented the differential phase shift quantum key distribution protocol and used low timing jitter 1.55 um single-photon detectors based on frequency up-conversion in periodically poled lithium niobate waveguides and silicon avalanche photodiodes. Based on the security analysis of the protocol against general individual attacks, we generated secure keys at a practical rate of 166 bit/s over 100 km of fiber. The use of the low jitter detectors also increased the sifted key generation rate to 2 Mbit/s over 10 km of fiber.
TL;DR: An all-optical half adder for bit-wise addition of two serial data streams that simultaneously generates Sum and Carry outputs is demonstrated and error free operation for RZ data is reported.
Abstract: We demonstrate an all-optical half adder for bit-wise addition of two serial data streams that simultaneously generates Sum and Carry outputs. The module performs the required XOR and AND operations using only two nonlinear optical elements. Difference Frequency Generation in a periodically poled lithium niobate waveguide serves as the AND gate and cross-gain modulation in a semiconductor optical amplifier is employed to generate the XOR output. Error free operation for RZ data is reported.
TL;DR: In this paper, the experimental demonstration of simultaneous dispersion and nonlinearity compensation in an embedded link characterized by strongly asymmetrical power profiles is presented by using a highly efficient optical phase conjugator based on a periodically poled lithium-niobate waveguide, combined with two small dispersion compensating elements properly inserted in the link.
Abstract: We report in this letter, the experimental demonstration of simultaneous dispersion and nonlinearity compensation in an embedded link characterized by strongly asymmetrical power profiles. This result is obtained by using a highly efficient optical phase conjugator based on a periodically poled lithium-niobate waveguide, combined with two small dispersion-compensating elements properly inserted in the link.
TL;DR: In this article, a Sagnac interferometer with a zero-area SAG loop for measuring magneto-optic Kerr effect (MOKE) at cryogenic temperatures is described.
Abstract: We describe a geometry for a Sagnac interferometer with a zero-area Sagnac loop for measuring magneto-optic Kerr effect (MOKE) at cryogenic temperatures. The apparatus is capable of measuring absolute polar Kerr rotation at 1550 nm wavelength without any modulation of the magnetic state of the sample, and is intrinsically immune to reciprocal effects such as linear birefringence and thermal fluctuation. A single strand of polarization-maintaining (PM) fiber is fed into a liquid helium probe, eliminating the need for optical viewports. This configuration makes it possible to conduct MOKE measurements at much lower temperatures than before. With an optical power of only 10 $\mu$W, we demonstrate static Kerr measurements with a shot-noise limited sensitivity of $1\times 10^{-7}$ rad/$\sqrt{\rm Hz}$ from room temperature down to 2K. Typical bias drift was measured to be $3\times 10^{-7}$ rad/hour.
TL;DR: In this paper, the authors quantified the mechanical dissipation associated with dielectric thin films formed from alternating layers of ion-beam-sputtered SiO2 and Ta2O5 and concluded that such dissipation could lead to potentially significant levels of thermally induced displacement noise in proposed advanced gravitational wave detectors.
Abstract: Previous studies have quantified the mechanical dissipation associated with dielectric thin films formed from alternating layers of ion-beam-sputtered SiO2 and Ta2O5 and concluded that such dissipation could lead to potentially significant levels of thermally induced displacement noise in proposed advanced gravitational wave detectors. We report here, for the first time, measurements of the mechanical dissipation of coatings formed from alternating layers of Al2O3 and Ta2O5, and SiO2 and Al2O3, respectively, when applied to fused silica substrates. In addition, we report our measurements of the elastic properties of Al2O3/Ta2O5 and SiO2/Ta2O5 coatings, as the film elastic properties can significantly influence expected levels of coating thermal noise. In summary, our analysis suggests that SiO2/Ta2O5 coatings currently present the best option for future detectors from a thermal noise standpoint.
TL;DR: In this article, the authors search for coincident gravitational wave signals from inspiralling neutron star binaries using LIGO and TAMA300 data taken during early 2003 using a simple trigger exchange method.
Abstract: We search for coincident gravitational wave signals from inspiralling neutron star binaries using LIGO and TAMA300 data taken during early 2003. Using a simple trigger exchange method, we perform an intercollaboration coincidence search during times when TAMA300 and only one of the LIGO sites were operational. We find no evidence of any gravitational wave signals. We place an observational upper limit on the rate of binary neutron star coalescence with component masses between 1 and 3M⊙ of 49 per year per Milky Way equivalent galaxy at a 90% confidence level. The methods developed during this search will find application in future network inspiral analyses.
TL;DR: A photon-counting OTDR system at 1.5 microm with a single-photon detector, which combines frequency upconversion in a periodically poled lithium niobate waveguide and a silicon avalanche photodiode, which exhibits high sensitivity, good spatial resolution, and short measurement time.
Abstract: Optical time-domain reflectometry (OTDR) is one of the most powerful
tools in the characterization of optical fiber links. We demonstrate a photon-counting
OTDR system at 1.5 μm with a single-photon detector, which combines frequency
upconversion in a periodically poled lithium niobate waveguide and a silicon
avalanche photodiode. The system exhibits high sensitivity, good spatial resolution,
and short measurement time.
TL;DR: In this article, the authors demonstrate the generation of multicycle narrowbandwidth terahertz pulses in periodically inverted GaAs structures using optical rectification of 2μm, 100fs pump pulses.
Abstract: The authors demonstrate the generation of multicycle narrow-bandwidth terahertz pulses in periodically inverted GaAs structures using optical rectification of 2μm, 100fs pump pulses. Three different types of orientation-inverted samples are employed: optically contacted multilayer, orientation-patterned, and diffusion-bonded GaAs. The terahertz pulses are characterized by two-color (pump at 2μm and probe at 0.8μm) terahertz time-domain spectroscopy and terahertz Michelson interferometry.
TL;DR: In this article, a fiber ring laser incorporating a periodically poled lithium niobate waveguide and two parallel-arranged tunable filters (TFs) was used to achieve flexible wavelength conversion from a changeable input signal wavelength to a variable output idler wavelength.
Abstract: Tunable wavelength conversion of picosecond (ps)-pulses based on cascaded sum- and difference frequency generation is proposed and demonstrated by use of a fiber ring laser incorporating a periodically poled lithium niobate waveguide and two parallel-arranged tunable filters (TFs). The pulsed signal with 40-GHz repetition rate and 1.57-ps pulsewidth is employed. No external pump and control sources are required in the wavelength converter. By properly adjusting two TFs to change the lasing pump and control wavelengths, flexible wavelength conversion from a changeable input signal wavelength to a variable output idler wavelength is achieved
TL;DR: In this paper, the authors showed that adding TiO$_2$ to Ta$_ 2$O$5$/SiO$2$ coatings reduces the internal friction and in addition present data confirming it reduces thermal noise.
Abstract: Reducing thermal noise from optical coatings is crucial to reaching the required sensitivity in next generation interferometric gravitational-waves detectors. Here we show that adding TiO$_2$ to Ta$_2$O$_5$ in Ta$_2$O$_5$/SiO$_2$ coatings reduces the internal friction and in addition present data confirming it reduces thermal noise. We also show that TiO$_2$-doped Ta$_2$O$_5$/SiO$_2$ coatings are close to satisfying the optical absorption requirements of second generation gravitational-wave detectors.
TL;DR: In this article, a scanning optical microscope based on polarization Sagnac interferometry for measuring ultrasmall phase shifts is described, and the authors use this method to detect small numbers of absorbing molecules in a solid without the use of fluorescence.
Abstract: We describe a scanning optical microscope based on polarization Sagnac interferometry for measuring ultrasmall phase shifts, and use this method to detect small numbers of absorbing molecules in a solid without the use of fluorescence. The absorption and concomitant optical phase shift of terrylene dopant molecules in a $p$-terphenyl host crystal are made time dependent by periodic optical saturation of the sample. A detection sensitivity of $8.75\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}\phantom{\rule{0.3em}{0ex}}\mathrm{rad}$ is achieved with a $0.078\phantom{\rule{0.3em}{0ex}}\mathrm{Hz}$ bandwidth, and detection of signals from as few as $19\ifmmode\pm\else\textpm\fi{}3$ terrylene molecules is demonstrated at room temperature.
TL;DR: A 1.5- mum band polarization independent single photon detector based on frequency up-conversion in periodically poled lithium niobate (PPLN) waveguides is reported and it is confirmed that the sifted key rate and error rate remained stable when the polarization state was changed during single photon transmission.
Abstract: We report a 1.5-µm band polarization independent single photon detector based on frequency up-conversion in periodically poled lithium niobate (PPLN) waveguides. To overcome the polarization dependence of the PPLN waveguides, we employed a polarization diversity configuration composed of two up-conversion detectors connected with a polarization beam splitter. We experimentally confirmed polarization independent single photon counting using our detector. We undertook a proof-of-principle differential phase shift quantum key distribution experiment using the detector, and confirmed that the sifted key rate and error rate remained stable when the polarization state was changed during single photon transmission.
29 Jan 2006
TL;DR: In this paper, the authors demonstrate a µW-level, 100MHz repetition rate THz source based on parametric down-conversion in orientation-patterned GaAs pumped by a femtosecond all-fiber laser at 2 µm.
Abstract: We demonstrate a µW-level, 100-MHz repetition rate THz source based on parametric down-conversion in orientation-patterned GaAs pumped by a femtosecond all-fiber laser at 2 µm. The demonstrated source should be suitable for imaging and spectroscopy.
Patent•
17 Feb 2006TL;DR: In this article, a method for generating THz radiation comprises illuminating a semiconductor crystal with an optical pulse train, with alternating parallel crystal domains, with each domain having a crystal orientation inverted with respect to adjacent domains.
Abstract: A method for generating THz radiation comprises illuminating a semiconductor crystal with an optical pulse train. The semiconductor crystal comprises alternating parallel crystal domains, with each domain having a crystal orientation inverted with respect to adjacent domains. The optical pulse train propagates substantially perpendicularly relative to domain boundaries in the semiconductor crystal. The THz radiation is generated from the optical pulse train by optical down-conversion mediated by the semiconductor crystal. Optical path lengths through the crystal domains at least in part determine a frequency of the generated THz radiation. THz generation efficiency may be enhanced by placing the semiconductor crystal within an external resonant cavity, by placing the semiconductor crystal within a laser cavity, or by placing the semiconductor crystal within an OPO cavity. The semiconductor crystal may comprise zinc-blende, III-V, or II-VI semiconductor.