Mohan, N., Minaeva, O., Goltsman, G. N., Saleh, M. F., Nasr, M. B., Sergienko, A. V., et al. (2009). Ultrabroadband coherence-domain imaging using parametric downconversion and superconducting single-photon detectors at 1064 nm. Appl. Opt., 48(20), 4009–4017.
Abstract: Coherence-domain imaging systems can be operated in a single-photon-counting mode, offering low detector noise; this in turn leads to increased sensitivity for weak light sources and weakly reflecting samples. We have demonstrated that excellent axial resolution can be obtained in a photon-counting coherence-domain imaging (CDI) system that uses light generated via spontaneous parametric downconversion (SPDC) in a chirped periodically poled stoichiometric lithium tantalate (chirped-PPSLT) structure, in conjunction with a niobium nitride superconducting single-photon detector (SSPD). The bandwidth of the light generated via SPDC, as well as the bandwidth over which the SSPD is sensitive, can extend over a wavelength region that stretches from 700 to 1500 nm. This ultrabroad wavelength band offers a near-ideal combination of deep penetration and ultrahigh axial resolution for the imaging of biological tissue. The generation of SPDC light of adjustable bandwidth in the vicinity of 1064 nm, via the use of chirped-PPSLT structures, had not been previously achieved. To demonstrate the usefulness of this technique, we construct images for a hierarchy of samples of increasing complexity: a mirror, a nitrocellulose membrane, and a biological sample comprising onion-skin cells.
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Scheel, S. (2009). Single-photon sources–an introduction. J. Modern Opt., 56(2-3), 141–160.
Abstract: This review surveys the physical principles and recent developments in manufacturing single-photon sources. Special emphasis is placed on important potential applications such as linear optical quantum computing (LOQC), quantum key distribution (QKD) and quantum metrology that drive the development of these sources of single photons. We discuss the quantum-mechanical properties of light prepared in a quantum state of definite photon number and compare it with coherent light that shows a Poissonian distribution of photon numbers. We examine how the single-photon fidelity directly influences the ability to transmit secure quantum bits over a predefined distance. The theoretical description of modified spontaneous decay, the main principle behind single-photon generation, provides the background for many experimental implementations such as those using microresonators or pillar microcavities. The main alternative way to generate single photons using postselection of entangled photon pairs from parametric down-conversion, will be discussed. We concentrate on describing the underlying physical principles and we will point out limitations and open problems associated with single-photon production.
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Karpowicz, N., Lu, X., & Zhang, X. - C. (2009). Terahertz gas photonics. J. Modern Opt., 56(10), 1137–1150.
Abstract: The underlying physics of the generation and detection of terahertz (THz) waves in gases are described. The THz wave generation process takes place in two steps: asymmetric gas ionization by two-frequency laser fields, followed by interaction of the ionized electron wave packets with the surrounding medium, producing an intense ‘echo' with tunable spectral content. In order to clarify the physical picture at the moment of ionization, the laser–atom interaction is treated through solution of the time-dependent Schrödinger equation, yielding an ab initio understanding of the release of the electron wave packets. The second step, where the electrons interact with the surrounding plasma is treated analytically. The resulting pressure dependence of the THz radiation is explored in detail. The THz wave detection process is shown to be the result of four-wave mixing, leading to analytical expressions of the signal obtained which allow for improved optimization of systems that exploit these effects.
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Polyakov, S. V., & Migdalla, A. L. (2009). Quantum radiometry. J. Modern Opt., 56(9), 1045–1052.
Abstract: We review radiometric techniques that take advantage of photon counting and stem from the quantum laws of nature. We present a brief history of metrological experiments and review the current state of experimental quantum radiometry.
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Doi, Y., Wang, Z., Ueda, T., Nickels, P., Komiyama, S., Patrashin, M., et al. (2009). CSIP – a novel photon-counting detector applicable for the SPICA far-infrared instrument. SPICA, (SPICA Workshop 2009).
Abstract: We describe a novel GaAs/AlGaAs double-quantumwell device for the infrared photon detection, called ChargeSensitive Infrared Phototransistor (CSIP). The principle of CSIP detector is the photo-excitation of an intersubband transition in a QW as an charge integrating gate and the signal ampli<ef><ac><81>cation by another QW as a channel with very high gain, which provides us with extremely high responsivity (104 – 106 A/W). It has been demonstrated that the CSIP designed for the mid-infrared wavelength (14.7 μm) has an excellent sensitivity; the noise equivalent power (NEP) of 7 × 10-19 W/ with the quantum effciency of ~ 2%. Advantages of the CSIP against the other highly sensitive detectors are, huge dynamic range of > 106, low output impedance of 103 – 104 Ohms, and relatively high operation temperature (> 2 K). We discuss possible applications of the CSIP to FIR photon detection covering 35 – 60 μm waveband, which is a gap uncovered with presently available photoconductors.
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