This PDF file contains the front matter associated with SPIE Proceedings Volume 9763, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.

Europium doped calcium fluoride is a machinable and alkaline-earth resistant crystal that is suitable for constructing a calcium or strontium vapor cell. However, its heat capacity, emissivity, and high coefficient of thermal expansion make it challenging to achieve optically dense calcium vapors for laser spectroscopy on narrow linewidth transitions. We discuss a low size, weight and power heating package that is under development at the Air Force Research Laboratory.

We discuss an optical atomic clock based on a two-photon transition at 778 nm in rubidium. In particular, we discuss the fundamental limitations to the short-term stability of a system based on a commercial C-band telecom laser as opposed to a near infrared laser. We show that this system is fundamentally capable of besting a hydrogen MASER in frequency stability and size.

Synchronization of optical clocks via optical two-way time-frequency transfer across free-space links can result in time offsets between the two clocks below tens of femtoseconds over many hours. The complex optical system necessary to support such synchronization is described in detail here.

We present a study of the identified for the first time effect of electromagnetically-induced transparency delay in Rb vapours on the atomic clock transition. The effect consists in the presence of a delay in the time of the maximal total transmission of atomic vapour relative to the moment when a two-photon resonance is reached as the frequency difference between two laser fields (FDLF) deviates around the clock transition frequency. It was found out that the delay is higher for higher frequencies of the FDLF modulation and is accompanied by substantial evolution of the width and shape of the coherent population trapping resonance.

We present a novel technique of efficient optical pumping of open, high-angular-momentum systems. The method combines two well-established approaches of population manipulation (conventional optical pumping and coherent population transfer), offering the ability to achieve higher population of a sublevel with the highest or lowest quantum number m (the “end state”) than obtainable with either of the techniques. To accomplish this task, we propose to use coherent-population-transfer technique (e.g., adiabatic fast passage) to arrange the system in such a way that spontaneously emitted photon (conventional optical pumping) carries away more entropy than in conventional schemes. This enables reduction of a number of spontaneous decays Nsd required to pump the system with the total angular momentum J from Nsd = J decays in the conventional scheme to Nsd ≲ log2(2J) decays in the proposed scheme. Since each spontaneous-emission event is potentially burdened with a loss of population (population is transferred to a dark state), this enables increasing population accumulated in the “end state”, which is important for many applications.

The precision, versatility and broad bandwidth of frequency combs are the basis of many different applications from the microwave via the millimeter and THz up to the optical range of the electromagnetic spectrum. Optical frequency combs can be used for the new definition of physical constants, for high-precision metrology and spectroscopy and for ultrahigh bitrate data communications, for instance. Besides the stability and the bandwidth, the most important parameters of a frequency comb are the free spectral range ,as well as the linewidth and amplitude of the single comb lines. A conventional grating based optical spectrometer can easily measure the bandwidth of the comb. However, it fails for the measurement of all other comb parameters, if the comb is generated by a mode-locked fiber laser for instance. Here we present a proof-of-concept setup for an optical spectrometer with a resolution in the kHz-range and first measurements of the free spectral range, linewidth and amplitude of a comb source. The spectrometer is based on the combination of optical heterodyning with the polarization pulling effect of stimulated Brillouin scattering. As we will discuss, the maximum possible resolution is only restricted by the linewidth and stability of the used reference laser. Thus due to the stability of our laser used as local oscillator, our setup has a maximum resolution of around 5 kHz or 40 attometer, corresponding to 11 orders of magnitude compared to the center frequency of the comb of around 190 THz.

We study Raman scattering in molecular media by applying two laser fields in a two-photon resonance with vibrational transition. The role of rotational levels has been investigated. It is shown that the molecular vibrational coherence strongly depends on the effect of coherent population trapping for rotational levels. The obtained results are important for application of Raman spectroscopy to molecular detection for engineering, chemical, and biological applications.

Over the last decade there has been a continuing interest in slow and stored light based on the electromagnetically induced transparency (EIT) effect, because of their potential applications in quantum information manipulation. However, previous experimental works all dealt with the single-component slow light which cannot be employed as a qubit. In this work, we report the first experimental demonstration of two-component or spinor slow light (SSL) using a double tripod (DT) atom-light coupling scheme. The oscillations between the two components, similar to the Rabi oscillation of a two-level system or a qubit, were observed. Single-photon SSL can be considered as two-color qubits. We experimentally demonstrated a possible application of the DT scheme as quantum memory and quantum rotator for the two-color qubits. This work opens up a new direction in the slow light research.

Recent progresses towards distance-limitless superluminal propagation based on stimulated Brillouin scattering have been presented. By suppressing multiple-longitudinal-mode lasing oscillation, Brillouin-induced superluminal propagation through hundreds-of-meter optical fibers can be successfully achieved.

Induced transparency and absorption effects are observed in the throughput of a hollow bottle microresonator using either mode coupling or superposition of two coresonant orthogonally polarized whispering gallery modes of very different quality factors (Q). The first method is based on intracavity cross polarization coupling when either the TE mode or the TM mode is driven, resulting in coupled mode induced transparency (CMIT) and coupled mode induced absorption (CMIA). The second method is based on superposition of the throughputs when the two modes are simultaneously driven by input light linearly polarized at an angle of 45° with respect to the TE-TM basis of the resonator, and throughput of the same polarization is detected. In this way, superposition can be created even in the absence of cross polarization coupling. The observations using the second method are referred to as coresonant polarization induced transparency and absorption (CPIT, CPIA). Coresonance between the TE and TM modes can be obtained by strain tuning. The above behaviors are analogous to electromagnetically induced transparency and absorption (EIT, EIA), and enable slow light and fast light, i.e., the delay or advancement of an incident resonant pulse. Experimental results representative of several different types of behavior are presented here. Induced transparency is seen to be accompanied by pulse delay, whereas induced absorption can be accompanied by pulse advancement or delay. The results are analyzed and explained by simple analytical modeling and by comparison to the output of a more detailed numerical model describing these effects.

The miniaturization of metal structures down to the nanoscale has been accompanied with several recent studies demonstrating plasmonic effects not explainable by classical electromagnetic theory. Describing the optical properties of materials solely through the bulk dielectric function has been augmented with quantum mechanical corrections, such as the electron spill-out effect and nonlocal response. Here, we discuss the latter and its implications on the waveguiding characteristics, such as dispersion and group velocity, of the surface-plasmon polariton mode supported at a metal-air interface.

Recent research on surface plasmon polaritons and their applications have brought forward a wealth of information and continues to be of interest to many. In this report, we concentrate on propagating surface plasmon polaritons (SPPs) and their interaction with matter. Using grating based metallic structures, it is possible to control the electrodynamics of propagating SPPs. Biharmonic gratings loaded with periodic Si stripes allow excitation of SPPs that are localized inside the band gap with grating coupling. The cavity state is formed due to periodic effective index modulation obtained by one harmonic of the grating and loaded Si stripes. More complicated grating structures such as metallic Moiré surfaces have also been shown to form a localized state inside the band gap when excited with Kretschmann configuration.

We report a new generation of slow-light FBG strain sensor with a strain resolution (or minimum detectable strain) as low as 30 fepsilon/√Hz at 30 kHz, which is one order of magnitude lower than the record held by the previous generation. This sensor has an ultra-stable output (no drift in 4 days) and is capable of resolving an absolute strain of ~250 attostrains by integrating its output for ~8 hours, which is also a new record for an FBG fiber sensor. These improvements were accomplished by first maximizing the slope of the slow-light resonances, and hence the strain sensitivity. To this end the apodized FBG was written in a deuterium-loaded fiber with a femtosecond infrared laser, then thermally annealed. The three main sources of noise in the sensor system were also carefully reduced. The dominant source of noise, laser frequency noise, was reduced by interrogating the FBG with an ultra-stable laser (linewidth under 200 Hz) with a low intensity noise. The phase noise was minimized by selecting the proper FBG length (~25 mm). When used as an acoustic sensor, the same grating had a measured average pressure resolution of 50 μPa/√Hz between 3 kHz and 6 kHz, one order of magnitude lower than the previous lowest reported value for an FBG sensor.

We demonstrate experimentally, an optically controlled dynamic photonic bandgap material, and to characterize its properties. The PhC device consists of colloidal particles assembled, using Holographic Optical Tweezers, into periodic structures located between prepositioned optical fibers. The positions of the optical traps can be modified in-situ in a well-controlled manner. The spectral transmission properties of the devices are experimentally to obtain the passbands and bandgaps. The desired structure and photonic band diagram of the photonic materials are calculated and optimized numerically using and plane wave simulations. Good agreement is found between the calculated band structure and the measured transmission spectrum for the different photonic crystal arrangements.

Adaptive holography is a promising method for high sensitivity phase modulation measurements in the presence of slow perturbations from the environment. The technique is based on the use of a nonlinear recombining medium, here an optically addressed spatial light modulator specifically realized to operate at 1.55 μm. Owing to the physical mechanisms involved, the interferometer adapts to slow phase variations within a range of 5-10 Hz, thus filtering out low frequency noise while transmitting higher frequency phase modulations. We present the basic principles of the adaptive interferometer and show that it can be used in association with a sensing fiber in order to detect phase modulations. Finally, a phase-OTDR architecture using the adaptive holographic interferometer is presented and shown to allows the detection of localized perturbations along the sensing fiber.

We report what we call co- and counter propagating slow-light systems based on the high nonlinearity in Si lattice-shifted photonic crystal waveguides (LSPCWs). The intense slow-light pulse, as a control pulse, efficiently generates two-photon absorption and carrier plasma effects, which tunes the dispersion characteristics of the LSPCWs and spectrum of copropagating or counter-propagating slow-light pulse, as a signal pulse. Using the control pulse, we succeeded in experimentally demonstrating adiabatic wavelength conversion and its enhancement, delay tuning of up to 10 ps with a response time <10 ps, and temporal pulse compression of factor 9.9 in the signal pulse. Furthermore, we discussed theoretically the collision and reflection of the signal pulse counterpropagating against the control pulse through the photonic-bandgap shift, resulting in a large Doppler shift. Considering the detail of these phenomena, we clarified the relation and difference between the adiabatic wavelength conversion, cross-phase modulation, and Doppler shift, which have been unclear so far.

We theoretically investigate the series-coupled double micro-ring resonator as tunable optical delay line. Tunable optical delay line can be achieved by tunable self-coupling coefficient and attenuation factor of micro-ring waveguide. Through choosing suitable parameters of structure, the series-coupled double micro-ring resonator can obtain flat delay line that mitigates the deleterious effects of group delay dispersion.

Induced transparency and absorption effects can be observed in the throughput of an optical microresonator that has two coresonant modes with very different quality factors. There are several different methods for achieving these effects, which enable slow light and fast light, i.e., the delay or advancement of an incident resonant pulse. For example, mode coupling can be employed. This coupling can take place between modes of the same polarization or modes of orthogonal polarization. Another method is based on superposition, when two orthogonally polarized modes are driven simultaneously by linearly polarized input light and throughput of the same polarization as the input is detected. In general, induced transparency is accompanied by pulse delay, whereas induced absorption can be accompanied by pulse advancement or delay. A number of different methods for producing induced transparency or absorption are compared here. Several properties are considered for comparison. One involves the widths of the induced transparency or absorption window and of the corresponding spectral region of steep dispersion. Achievable pulse delays or advancements, along with pulse distortion and delay-bandwidth (or advancement-bandwidth) products, are also compared. Different methods allow for different amounts of control over various system parameters, and these are compared as well. The differences among the several methods are evaluated in consideration of suitability for employment in various applications.

We present resonant four-wave mixing (FWM) signals involving a Rydberg state in a thermal Rb vapor. The dynamic behavior of the FWM signals exhibits revival peaks shortly after the incident pulse, which are due to coherent collective emission among all Doppler classes. The FWM signals have dephasing times up to 7 ns, and strongly depend on the excitation bandwidth to the Rydberg state. Our numerical simulations based on a four-level model including the whole Doppler broadened ensemble can describe the data quite well.

The transient stimulated Brillouin scattering amplification of a step-function signal wave is examined analytically. Prior to reaching a steady state, the logarithmic gain coefficient of the signal wave is oscillating at a frequency that is given by the detuning of the stimulated acoustic wave from the Brillouin frequency shift (BFS) of the medium. The study of a single transient trace, taken at an arbitrary known frequency offset between pump and signal, may recover the BFS of the medium. The measurement protocol does not involve spectral scanning. The technique may increase the acquisition rate in high-resolution, distributed Brillouin fiber sensor setups.

The nonlinear phase shift per unit length acquired by the transmitted and phase conjugate waves in backward-wave four-wave mixing may be considered as an effective refractive index. Consequently, a narrow spectrum of the nonlinear phase shift in non-degenerate frequency interaction corresponds to natural dispersion and such interaction may be used for temporal manipulation of light pulses. Analysis of the narrow spectra of the nonlinear phase shift shows high potential of the backward-wave four-wave for slowing down of light pulses. The slowing down is achieved using backward-wave four-wave mixing in media with local and nonlocal response. The delay and shape transformation of output pulses are studied and compared for the transmitted and phase conjugate channels. It is shown that the phase conjugate pulse achieves a longer delay under typical experimental conditions.

Classical, semi-classical, and quantum-field descriptions for the interaction of light with matter are systematically discussed. Applications of interest include precise determinations of the linear and the non-linear electromagnetic response relevant to resonant pump-probe optical phenomena, such as electromagnetically induced transparency. In the quantum-mechanical description of matter systems, we introduce a general reduced-density-matrix framework. Time-domain (equation-of-motion) and frequency-domain (resolvent-operator) formulations are developed in a unified and self-consistent manner, using a Liouville-space operator representation. A preliminary semi-classical perturbation treatment of the electromagnetic interaction is adopted, in which the electromagnetic field is described as a classical field satisfying the Maxwell equations. Compact Liouville-space operator expressions are derived for the linear and the general (nth order) non-linear electromagnetic-response tensors describing moving many-electron systems. The tetradic matrix elements of the Liouville-space self-energy operators, which are introduced in the time-domain and frequency-domain formulations, are evaluated for environmental collisional and radiative interactions, in order to provide explicit forms for the quantum kinetic equations and the spectral-line shape formulas. It is emphasized that a quantized-field approach is essential for a fully self-consistent quantum-mechanical description of the interacting light-matter system.

We investigate the influence of the finite absorption spectrum width on the soliton formation and superluminality phenomenon at a femtosecond pulse propagation in a medium with noble nanoparticles. These effects take place if a positive phase-amplitude grating is induced by laser radiation. We take into account the two-photon absorption (TPA) of laser radiation by nanorods, and time-dependent nanorod aspect ratio changing due to their melting or reshaping because of laser energy absorption, and the nanorod absorption spectrum width. On the basis of computer simulation we demonstrate these effects in a medium with positive phase-amplitude grating, induced by laser radiation, if a weak laser energy absorption takes place on the laser pulse dispersion length.