Showing papers by "Martin M. Fejer published in 2013"
TL;DR: In this paper, the authors present the current best estimate of the plausible observing scenarios for the Advanced LIGO, Advanced Virgo and KAGRA detectors over the next several years, with the intention of providing information to facilitate planning for multi-messenger astronomy with gravitational waves.
Abstract: We present our current best estimate of the plausible observing scenarios for the Advanced LIGO, Advanced Virgo and KAGRA gravitational-wave detectors over the next several years, with the intention of providing information to facilitate planning for multi-messenger astronomy with gravitational waves. We estimate the sensitivity of the network to transient gravitational-wave signals for the third (O3), fourth (O4) and fifth observing (O5) runs, including the planned upgrades of the Advanced LIGO and Advanced Virgo detectors. We study the capability of the network to determine the sky location of the source for gravitational-wave signals from the inspiral of binary systems of compact objects, that is BNS, NSBH, and BBH systems. The ability to localize the sources is given as a sky-area probability, luminosity distance, and comoving volume. The median sky localization area (90\% credible region) is expected to be a few hundreds of square degrees for all types of binary systems during O3 with the Advanced LIGO and Virgo (HLV) network. The median sky localization area will improve to a few tens of square degrees during O4 with the Advanced LIGO, Virgo, and KAGRA (HLVK) network. We evaluate sensitivity and localization expectations for unmodeled signal searches, including the search for intermediate mass black hole binary mergers.
536 citations
TL;DR: Up-conversion single-photon detectors with high efficiency and low noise are developed to faithfully demonstrate the measurement-device-independent quantum-key-distribution protocol, which is immune to all hacking strategies on detection and employed to defend attacks on a nonideal source.
Abstract: Quantum key distribution is proven to offer unconditional security in communication between two remote users with ideal source and detection. Unfortunately, ideal devices never exist in practice and device imperfections have become the targets of various attacks. By developing up-conversion single-photon detectors with high efficiency and low noise, we faithfully demonstrate the measurement-device-independent quantum-key-distribution protocol, which is immune to all hacking strategies on detection. Meanwhile, we employ the decoy-state method to defend attacks on a nonideal source. By assuming a trusted source scenario, our practical system, which generates more than a 25 kbit secure key over a 50 km fiber link, serves as a stepping stone in the quest for unconditionally secure communications with realistic devices.
378 citations
TL;DR: Based on the new detector, a single-pixel up-conversion infrared spectrometer with a noise equivalent power of -142 dBm Hz(-1/2) was demonstrated, which was as good as a liquid nitrogen cooled CCD camera.
Abstract: We demonstrate up-conversion single-photon detection for the 1550-nm telecommunications band using a PPLN waveguide, long-wavelength pump, and narrowband filtering using a volume Bragg grating. We achieve total-system detection efficiency of around 30% with noise at the dark-count level of a Silicon APD. Based on the new detector, a single-pixel up-conversion infrared spectrometer with a noise equivalent power of −142 dBm Hz-1/2 was demonstrated, which was as good as a liquid nitrogen cooled CCD camera.
75 citations
TL;DR: In this article, a systematic and optimized approach to grating construction is provided, and different apodization techniques are compared where appropriate, where the poling period is varied smoothly, monotonically, and rapidly at the edges of the device.
Abstract: Chirped quasi-phasematching (QPM) optical devices offer the potential for ultrawide bandwidths, high conversion efficiencies, and high amplification factors across the transparency range of QPM media. In order to properly take advantage of these devices, apodization schemes are required. We study apodization in detail for many regimes of interest, including low-gain difference frequency generation (DFG), high-gain optical parametric amplification (OPA), and high-efficiency adiabatic frequency conversion (AFC). Our analysis is also applicable to second-harmonic generation, sum frequency generation, and optical rectification. In each case, a systematic and optimized approach to grating construction is provided, and different apodization techniques are compared where appropriate. We find that nonlinear chirp apodization, where the poling period is varied smoothly, monotonically, and rapidly at the edges of the device, offers the best performance. We consider the full spatial structure of the QPM gratings in our simulations, but utilize the first order QPM approximation to obtain analytical and semi-analytical results. One application of our results is optical parametric chirped pulse amplification; we show that special care must be taken in this case to obtain high gain factors while maintaining a flat gain spectrum.
74 citations
TL;DR: In this article, an upconversion single-photon detection for the 1550-nm band using a PPLN waveguide, longwavelength pump, and narrowband filtering using a volume Bragg grating was demonstrated.
Abstract: We demonstrate upconversion single-photon detection for the 1550-nm band using a PPLN waveguide, long-wavelength pump, and narrowband filtering using a volume Bragg grating. We achieve total-system detection efficiency of around 30% with noise at the dark-count level of a silicon APD. Based on the new detector, a single-pixel up-conversion infrared spectrometer with a noise equivalent power of -142 dBm was demonstrated, which was better than liquid nitrogen cooled InGaAs arrary.
72 citations
TL;DR: Apodized aperiodically poled MgO:LiNbO3 crystals with a negative chirp rate are employed as gain media to achieve ultrabroadband phase-matching while minimizing optical parametric generation.
Abstract: We generate sub-four-cycle pulses (41.6 fs) with 12 μJ of pulse energy in the mid-infrared spectral range (center wavelength 3.4 μm) from a high-repetition-rate, collinear three-stage optical parametric chirped-pulse amplifier (OPCPA) operating at 50 kHz. Apodized aperiodically poled MgO:LiNbO3 crystals with a negative chirp rate are employed as gain media to achieve ultrabroadband phase-matching while minimizing optical parametric generation. The seed pulses are obtained via a 1.56 μm femtosecond fiber laser, which is spectrally broadened in a dispersion-shifted telecom fiber to support 1000 nm bandwidth idler pulses in the mid-infrared.
70 citations
TL;DR: Low-noise and efficient frequency conversion by sum-frequency mixing in a periodically poled LiNbO(3) (PPLN) waveguide is demonstrated and the impact of low-no noise frequency translation on single-photon upconversion detection and quantum information applications is discussed.
Abstract: We demonstrate low-noise and efficient frequency conversion by sum-frequency mixing in a periodically poled LiNbO3 (PPLN) waveguide. Using a 1556 nm pump, 1302 nm photons are efficiently converted to 709 nm photons. We obtain 70% conversion efficiency in the PPLN waveguide and >50% external conversion efficiency with 600 noise counts per second at peak conversion with continuous-wave pumping. We simultaneously achieve low noise and high conversion efficiency by careful spectral filtering. We discuss the impact of low-noise frequency translation on single-photon upconversion detection and quantum information applications.
60 citations
Journal Article•
TL;DR: An ultrafast downconversion quantum interface is reported, where 910-nm single photons from a quantum dot are downconverted to the 1.5- μm telecom band with sub-10 picosecond pulses at 2.2-μm, enabling the demonstration of quantum-dot spin-photon entanglement.
Abstract: We report an ultrafast downconversion quantum interface, where 910-nm single photons from a quantum dot are downconverted to the 1.5-μm telecom band with sub-10 picosecond pulses at 2.2-μm, enabling the demonstration of quantum-dot spin-photon entanglement.
56 citations
TL;DR: In this article, the authors investigated the effects of V/III flux ratio and growth rate on the propagation and annihilation of antiphase boundaries during the overgrowth step of GaP films.
55 citations
TL;DR: In this article, a combination of electron diffraction data and atomic modelling using molecular dynamics was used to probe the atomic structure of these coatings, and examine the correlations between changes in the atomic structures and changes in mechanical loss of the coatings.
53 citations
TL;DR: In this article, the Fourier spectrum properties of the QPM grating in the presence of random duty cycle (RDC) errors in quasi-phase-matching (QPM) gratings lead to a pedestal in the spatial-frequency spectrum that increases the conversion efficiency for nominally phase mismatched processes.
Abstract: Random duty cycle (RDC) errors in quasi-phase-matching (QPM) gratings lead to a pedestal in the spatial-frequency spectrum that increases the conversion efficiency for nominally phase-mismatched processes. Here, we determine the statistical properties of the Fourier spectrum of the QPM grating in the presence of RDC errors. We illustrate these properties with examples corresponding to periodic gratings with parameters typical for continuous-wave interactions, and chirped gratings with parameters typical for devices involving broad optical bandwidths. We show how several applications are sensitive to RDC errors by calculating the conversion efficiency of relevant nonlinear-optical processes. Last, we propose a method to efficiently incorporate RDC errors into coupled-wave models of nonlinear-optical interactions while still retaining only a small number of QPM grating orders.
TL;DR: The first results of complete state tomography of a solid-state spin-photon-polarization-entangled qubit pair, using a single electron-charged indium arsenide quantum dot are reported, and the first achievement of a fidelity that will unambiguously allow for entanglement distribution inSolid-state quantum repeater networks is demonstrated.
Abstract: Entanglement between stationary quantum memories and photonic qubits is crucial for future quantum communication networks. Although high-fidelity spin-photon entanglement was demonstrated in well-isolated atomic and ionic systems, in the solid-state, where massively parallel, scalable networks are most realistically conceivable, entanglement fidelities are typically limited due to intrinsic environmental interactions. Distilling high-fidelity entangled pairs from lower-fidelity precursors can act as a remedy, but the required overhead scales unfavourably with the initial entanglement fidelity. With spin-photon entanglement as a crucial building block for entangling quantum network nodes, obtaining high-fidelity entangled pairs becomes imperative for practical realization of such networks. Here we report the first results of complete state tomography of a solid-state spin-photon-polarization-entangled qubit pair, using a single electron-charged indium arsenide quantum dot. We demonstrate record-high fidelity in the solid-state of well over 90%, and the first (99.9%-confidence) achievement of a fidelity that will unambiguously allow for entanglement distribution in solid-state quantum repeater networks.
TL;DR: Temporal imaging for the measurement and characterization of optical arbitrary waveforms and events is demonstrated and modulated pulse trains characterize the system's impulse response, jitter, and frame-to-frame variation.
Abstract: We demonstrate temporal imaging for the measurement and characterization of optical arbitrary waveforms and events. The system measures single-shot 200 ps frames at a rate of 104 MHz, where each frame is time magnified by a factor of -42.4x. Impulse response tests show that the system enables 783 fs resolution when placed at the front end of a 20 GHz oscilloscope. Modulated pulse trains characterize the system’s impulse response, jitter, and frame-to-frame variation.
TL;DR: This work demonstrates a photon-counting optical time-domain reflectometry with 42.19 dB dynamic range using an ultra-low noise up-conversion single photon detector and shows that the system can identify defects along the entire fiber length in a measurement time of 13 minutes.
Abstract: We demonstrate a photon-counting optical time-domain reflectometry with 42.19 dB dynamic range using an ultra-low noise up-conversion single photon detector. By employing the long-wave pump technique and a volume Bragg grating, we achieve a noise equivalent power of -139.7 dBm/√Hz for our detector. We perform the OTDR experiments using a fiber of length approximate 217 km, and show that our system can identify defects along the entire fiber length in a measurement time of 13 minutes.
TL;DR: In this article, the authors employed ultrafast coincidence detection based on sum-frequency generation in a periodically poled lithium niobate waveguide with a record-high pair conversion efficiency.
Abstract: We demonstrate dispersion cancellation of entangled photons for arbitrary spectral orders, generalizing Franson cancellation typically considered in second order alone. Employing ultrafast coincidence detection based on sum-frequency generation in a periodically poled lithium niobate waveguide with a record-high pair conversion efficiency of ${10}^{\ensuremath{-}5}$, we verify cancellation of dispersion up to fifth order. Cancellation of odd-order phase is experimentally shown to require identical signal and idler dispersion coefficients, in contrast to even-order phase, which cancels with opposite signs. These results are especially important for future work on ultrabroadband biphotons.
TL;DR: A high-efficiency waveguide is used to demonstrate the sum-frequency generation between a single photon and a single-photon level coherent state, directly applicable to future quantum communication technologies such as device-independent quantum key distribution.
Abstract: The parametric interaction of light beams in nonlinear materials is usually thought to be too weak to be observed when the fields involved are at the single-photon level. However, such single-photon level nonlinearity is not only fundamentally fascinating but holds great potential for emerging technologies and applications involving heralding entanglement at a distance. Here we use a high-efficiency waveguide to demonstrate the sum-frequency generation between a single photon and a single-photon level coherent state. The use of an integrated, solid state, room temperature device and telecom wavelengths makes this type of system directly applicable to future quantum communication technologies such as device-independent quantum key distribution.
TL;DR: In this article, the photothermal common-path interferometric technique was used to detect sub-ppm levels of optical absorption and track its changes at a given wavelength when a second laser beam is also incident on a thin film oxide sample.
Abstract: Tantalum pentoxide (Ta2O5) and silicon dioxide (SiO2) are common high-index and low-index materials used in dielectric optical coatings for high average-power lasers since high-density sputtered oxide films with absorption losses at near- and mid-infrared wavelengths of less than 1 ppm can be obtained. These oxides have been chosen to investigate the spontaneous and optically induced absorption at λ0 = 1064 nm that occurs due to simultaneous illumination at shorter wavelengths. The effect is measured using the photothermal common-path interferometric technique. This technique is capable of detecting sub-ppm levels of optical absorption and tracking its changes at a given wavelength when a second laser beam is also incident on a thin film oxide sample. In this work, dual beam experiments are employed to assess changes in the optical absorption at λ0 = 1064 nm in ion beam sputtered Ta2O5 and SiO2 thin films deposited on fused silica substrates, with stimulating illumination λ1 ranging from λ1 = 266 nm to λ1...
TL;DR: This work demonstrates a reconfigurable optical transmitter of higher-order modulation formats including pulse-amplitude-modulation (PAM) signals and quadrature-amphitude- modulation (QAM) signal formats using 10 Gbit/s on-off-keying signals.
Abstract: We demonstrate a reconfigurable optical transmitter of higher-order modulation formats including pulse-amplitude-modulation (PAM) signals and quadrature-amplitude-modulation (QAM) signals. We generated six different modulation formats by multiplexing 10 Gbit/s on–off-keying (OOK) signals (10 Gbaud binary phase-shift keying, 4-PAM, 8-PAM quadrature phase-shift keying (QPSK), 16-QAM and 16-star-QAM with error-vector magnitudes (EVMs) of 8.1%, 7.5%, 7.8%, 8.2%, 7.2%, and 6.9%, respectively) and 80 Gbit/s 16-QAM with an EVM of 8.5%, as well as 120 Gbit/s 64-QAM with an EVM of 7.1%, using two or three 40 Gbit/s QPSK signals, respectively. We also successfully transmitted the generated 16-QAM signals through a 100 km transmission line with negligible power penalty.
TL;DR: A system photon detection efficiency of 10%, with a noise count rate of 24,500 counts per second, competitive with other 2 μm single photon detection technologies, has potential applications in environmental gas monitoring, life science, and classical and quantum communication.
Abstract: We have demonstrated upconversion detection at the single photon level in the 2 μm spectral window using a pump wavelength near 1550 nm, a periodically poled lithium niobate (PPLN) waveguide, and a volume Bragg grating (VBG) to reduce noise. We achieve a system photon detection efficiency of 10%, with a noise count rate of 24,500 counts per second, competitive with other 2 μm single photon detection technologies. This detector has potential applications in environmental gas monitoring, life science, and classical and quantum communication.
TL;DR: By programming the complex spectral transmission function corresponding to a Mach-Zehnder interferometer, this work constructs variations on Franson interferometers that are free from mechanical instabilities, demonstrating spectral phase independence in the slow-detector limit, in which all temporal features are unobservable.
Abstract: We demonstrate spectral shaping of entangled photons in the telecom band with a programmable, fiber-based optical filter. The fine-resolution spectral control permits implementation of length-40 Hadamard codes, through which we are able to verify frequency anticorrelation with a 20-fold increase in total counts over that permitted by the equivalent pair of monochromators at the same input flux. By programming the complex spectral transmission function corresponding to a Mach–Zehnder interferometer, we also construct variations on Franson interferometers that are free from mechanical instabilities, demonstrating spectral phase independence in the slow-detector limit, in which all temporal features are unobservable. Our configuration furnishes a single, compact arrangement for manipulating telecom biphotons and characterizing their quality.
TL;DR: It is shown that with this approach, globally optimum solutions to several important QPM design problems can be determined and the optimization framework is highly versatile, enabling the user to trade-off different objectives and constraints according to the particular application.
Abstract: We propose a new approach to quasi-phasematching (QPM) design based on convex optimization. We show that with this approach, globally optimum solutions to several important QPM design problems can be determined. The optimization framework is highly versatile, enabling the user to trade-off different objectives and constraints according to the particular application. The convex problems presented consist of simple objective and constraint functions involving a few thousand variables, and can therefore be solved quite straightforwardly. We consider three examples: (1) synthesis of a target pulse profile via difference frequency generation (DFG) from two ultrashort input pulses, (2) the design of a custom DFG transfer function, and (3) a new approach enabling the suppression of spectral gain narrowing in chirped-QPM-based optical parametric chirped pulse amplification (OPCPA). These examples illustrate the power and versatility of convex optimization in the context of QPM devices.
TL;DR: A reconfigurable optical tapped delay line is experimentally demonstrated in conjunction with coherent detection to search multiple patterns among quadrature phase shift keying (QPSK) symbols in 20 Gbaud data channel and also to equalize 20 and 31 G baud QPSK, 20 GBaud 8 phase shiftkeying (PSK), and 16 QAM signals.
Abstract: We experimentally demonstrate a reconfigurable optical tapped delay line in conjunction with coherent detection to search multiple patterns among quadrature phase shift keying (QPSK) symbols in 20 Gbaud data channel and also to equalize 20 and 31 Gbaud QPSK, 20 Gbaud 8 phase shift keying (PSK), and 16 QAM signals. Multiple patterns are searched successfully on QPSK signals, and correlation peaks are obtained at the matched patterns. QPSK, 8 PSK, and 16 QAM signals are also successfully recovered after 25 km of SMF-28 with average EVMs of 8.3%, 8.9%, and 7.8%. A penalty of <1 dB optical signal to noise penalty is achieved for a 20 Gbaud QPSK signal distorted by up to 400 ps/nm dispersion.
TL;DR: Measure data indicates these lasers are not typically mode-locked, so their characterization is difficult to characterize because they are typically unstable, have low peak powers, and high bandwidth.
Abstract: Current pulse measurement methods have proven inadequate to fully understand the characteristics of passively mode-locked quantum-dot diode lasers. These devices are very difficult to characterize because of their low peak powers, high bandwidth, large time-bandwidth product, and large timing jitter. In this paper, we discuss the origin for the inadequacies of current pulse measurement techniques while presenting new ways of examining frequency-resolved optical gating (FROG) data to provide insight into the operation of these devices. Under the assumptions of a partial coherence model for the pulsed laser, it is shown that simultaneous time-frequency characterization is a necessary and sufficient condition for characterization of mode-locking. Full pulse characterization of quantum dot passively mode-locked lasers (QD MLLs) was done using FROG in a collinear configuration using an aperiodically poled lithium niobate waveguide-based FROG pulse measurement system.
19 Nov 2013
TL;DR: In this paper, the properties and laser damage behavior of Ta2O5/SiO2 quarter wave stacks designed for λ=1 µm operation by substituting the Ta 2O5 layer by either Y 2O3 or HfO2 and the SiO2 by Al2O3 in the top 3 pairs of the multilayer stack were investigated.
Abstract: We have investigated the properties and laser damage behavior of Ta2O5/SiO2 quarter wave stacks designed for λ=1 µm operation by substituting the Ta2O5 layer by either Y2O3 or HfO2 and the SiO2 by Al2O3 in the top 3 pairs of the multilayer stack. The high reflectors were deposited by dual ion beam sputtering. Laser damage at 1 µm using 350 ps showed enhanced performance when the Ta2O5/SiO2 stack had HfO2 or Y2O3 in its top few pairs. targets were used. For the present study fused silica substrates, with surface roughness of ~ 6 A were used. The total thickness of each HR stack was ~ 5 µm. The surface quality of the IBS HR was determined using an atomic force microscopy (AFM) using a NovaScan ESPM 3D operated in tapping mode. Root mean square (RMS) surface roughness was calculated using the included software for AFM. Glancing angle x-ray diffraction scans of the single layers showed the films are amorphous. Optical properties of the transparent films were investigated using a spectrophotometer in the wavelength range 190 to 1100 nm. Scattering measurements were performed using total integrating sphere with laser light illumination at λ=1.064 µm (details to be published elsewhere). The optical absorption loss of the coatings deposited on fused silica, was measured at λ = 1.064 µm with the photothermal common-path interferometry (PCI) 7 . Laser damage measurements were performed using 100-on-1 test at λ= 1.03
TL;DR: The theoretical spectral response of the upconversion detector as a function of pump power is calculated and excellent agreement with upconversions spectra measured in a periodically poled LiNbO₃ waveguide is obtained.
Abstract: We investigate the spectral response of an upconversion detector theoretically and experimentally, and discuss implications for its use as an infrared spectrometer. Upconversion detection is based on high-conversion-efficiency, sum-frequency generation (SFG). The spectral selectivity of an upconversion spectrometer is determined by the SFG spectral response function. This function changes with varying pump power. Working at maximum internal conversion efficiency is desirable for high sensitivity of the system, but the spectral response function is different at this pump power compared to the response function at low power. We calculate the theoretical spectral response of the upconversion detector as a function of pump power and obtain excellent agreement with upconversion spectra measured in a periodically poled LiNbO3 waveguide.
TL;DR: The intrinsic and 532 nm-induced optical absorption of 5 mol.
Abstract: We have measured the intrinsic and 532 nm-induced optical absorption of 5 mol. % MgO-doped lithium niobate crystals at 488 nm wavelength. The measurements have been conducted employing a photothermal common-path interferometer. The absorption at 488 nm increases on simultaneous illumination with 532 nm light. This induced absorption rises linearly with the stimulating 532 nm radiation power and saturates for intensities larger than 50 kW/cm2. A model developed recently, considering the excitation of electrons from levels near the valence band into iron centers, is applied to explain the observations.
17 Mar 2013
TL;DR: An all-optical scheme of phase noise reduction using optical nonlinearity and dispersion/conversion delay is proposed and demonstrated that can be reduced from 31% to 11% for ~500 MHz phase noise bandwidth on 20-Gbaud QPSK input.
Abstract: We propose and demonstrate an all-optical scheme of phase noise reduction using optical nonlinearity and dispersion/conversion delay. This scheme is capable of reducing the standard deviation of phase noise with low frequency component (e.g., laser phase noise) by a factor of ~ 4 without degrading the data signal. The EVM can be reduced from 31% to 11% for ~500 MHz phase noise bandwidth on 20-Gbaud QPSK input.
09 Jun 2013
TL;DR: In this article, the authors demonstrate the generation of optical 16-QAM and 64QAM at EVM 6.8% and 6.4% respectively using nonlinearities and coherent frequency comb.
Abstract: We demonstrate the generation of optical 16-QAM and 64-QAM at EVM 6.8% and 6.4% respectively using nonlinearities and coherent frequency comb. We also demonstrated a successful transmission through 80-km SMF-28 after compensating with 20-km DCF with negligible penalty.
TL;DR: A tunable optical tapped delay line that can simultaneously and independently operate on multiple wavelength-division multiplexed (WDM) data signals and a phase-preserving scheme enables coherent addition of the weighted taps is demonstrated.
Abstract: We demonstrate a tunable optical tapped delay line that can simultaneously and independently operate on multiple wavelength-division multiplexed (WDM) data signals. The system utilizes the wavelength-dependent speed of light, together with nonlinear wavelength conversion stages. A phase-preserving scheme enables coherent addition of the weighted taps. We reconfigured the system to perform separate simultaneous correlation (data pattern recognition), equalization, and modulation format conversion on four and eight WDM binary/quadrate phase-shift keyed channels at 26 and 20 Gbaud, respectively. The aggregate throughput of 416 Gb/s is achieved.
TL;DR: A reconfigurable optical converter/encoder for quadrature amplitude modulated (QAM) signals is experimentally demonstrate and baud rate tunability is shown and conversions from lower-order QAM signals to higher-orderQAM signals are shown.
Abstract: We experimentally demonstrate a reconfigurable optical converter/encoder for quadrature amplitude modulated (QAM) signals. The system utilizes nonlinear wavelength multicasting, conversion-dispersion delays, and simultaneous nonlinear multiplexing and sampling. We show baud rate tunability (31 and 20 Gbaud) and reconfigurable conversions from lower-order QAM signals to higher-order QAM signals (e.g., 64-QAM).