This PDF file contains the front matter associated with SPIE Proceedings Volume 8636, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and Conference Committee listing.

The throughput of a single fiber-coupled whispering-gallery microresonator, such as a fused-silica microsphere, can exhibit behavior analogous to electromagnetically induced transparency and absorption (EIT, EIA). These effects enable slow and fast light, respectively, in the form of pulse delay or advancement. Two different methods can be used to realize this behavior; in both methods, the key feature is the use of two coresonant orthogonally polarized whisperinggallery modes of very different quality factor (Q). The first method relies on intracavity cross-polarization coupling when only one mode is driven, and the second method uses a simple superposition of orthogonal throughputs (in the absence of intracavity cross-polarization mode coupling) when the two modes are simultaneously driven. We refer to the behavior observed using the first method as coupled-mode induced transparency and absorption (CMIT, CMIA), and the behavior of the second method as coresonant polarization induced transparency and absorption (CPIT, CPIA). In both cases, polarization-sensitive detection of the throughput is used, and the EIT/EIA analog features are observed on the same polarization component as that of the linearly polarized input. Some predictions of a numerical model of these processes are presented here. In addition to a discussion of these predictions, which assume conditions accessible to experiment, some experimental results are briefly described.

We describe a new type of interferometer, the coupled spiral interferometer (CSPIN), which consists in a planar spiral-shaped waveguide with optical coupling between adjacent arms. We demonstrate through numerical simulations that when the arms are phase matched and contain straight parallel sections, a CSPIN supports strong slow-light resonances that are periodic in frequency and in the coupling coefficient of the arms. Compared to existing coupled resonator optical waveguides (CROWs), it presents the significant benefit of greater compactness (as 1/N, where N is the number of coupled resonators, or equivalently the number of arms). Being two dimensional, it is also easier to fabricate than a coil optical resonator (COR). We illustrate this concept with a spiral in the shape of a square with rounded corners and two arms. Resonant conditions in wavelength and coupling coefficient are shown to exist for which the group delay goes to infinity and the transmission goes to zero, as in a COR. The effective group delay (product of group delay and transmission), a useful figure of merit to quantify the efficacy with which light can be slowed down, is maximum on both sides of a wavelength resonance. For a square spiral ~70 mm in length made of a low-loss (0.16 m^-1) silicon nitride waveguide, the maximum effective group delay is 15.9 ns (or a slow-down factor of 34.6). This value is independent of the number of arms (for a small loss), and it is the same value as for a COR with the same length and loss (for any N) and for a CROW with two resonators. This study shows that CSPINs offer a wide range of exciting new opportunities for implementing and utilizing slow light in numerous applications on a highly compact platform.

We develop a general framework of evaluating slow-light performance using Stimulated Brillouin Scattering (SBS) in optical waveguides via the overlap integral between optical and elastic eigen-modes. We show that spatial symmetry of the optical force dictates the selection rules of the excitable elastic modes. By applying this method to a rectangular silicon waveguide, we demonstrate the spatial distributions of optical force and elastic eigen-modes jointly determine the magnitude and scaling of SBS gain coefficient in both forward and backward SBS processes. We further apply this method to inter-modal SBS process, and demonstrate that the coupling between distinct optical modes is necessary to excite elastic modes with all possible symmetries.

We demonstrate slow light in dye-doped chiral liquid crystals. The medium combines a nematic liquid crystal with methyl-red and chiral agents. When a circularly polarized pump and a pulse beam interact in the cell, the output pulse is delayed thanks to the dispersive properties of the beam coupling occurring in the medium. The origin of the slow-light effect is explained on the basis of photo-isomerization induced transparency of the dye molecules hosted in the chiral liquid crystal structure.

A high-intensity laser pulse can lead to a change of the group index of a material, so that the pulse within that material is slowed to only hundreds of meters per second. This kind of slow-light phenomenon scales with the optical intensity of the pulse. While previous experiments have produced this effect with an elliptical beam passing through a spinning ruby window, a question remains as to whether the effect would be present in a circular beam. Here we use two different methods of producing slow light in a round beam, showing that, while less pronounced than the effect with an elliptical beam, a slow-light effect can be seen in a round beam.

We investigate the propagation of a weak probe laser field in a medium of warm Rb atoms, controlled with two strong resonant pump fields tuned to the D1 and D2 optical transitions to form an N-scheme arrangement. We have shown theoretically that four-wave mixing has a profound effect on the probe-field group velocity and absorption, allowing the probe-field propagation to be continuously tuned from superluminal to slow-light regimes with amplification. We have also identified the experimental conditions for observation of such tunable slow-to-fast light regime (continuously through the point of zero group index) with positive probe-field gain, and demonstrated that the spectral range corresponding to the zero group index can be tuned by controlling the power of one of the pump laser.

We present an entirely linear all-optical method of dispersion enhancement using coupled cavities that leads to a substantial increase in system transmission in comparison with atom-cavity systems. This is achieved by tuning the system to an anomalous dispersion condition by under-coupling at least one of the cavities to the other. The intracavity anomalous dispersion is then associated with a dip in reflection (and in turn with a peak in transmission) rather than with an absorption resonance as in the case of the atomic vapor. We find that in contrast with the atom-cavity system where mode reshaping always contributes to the mode pushing, in coupled cavity systems reshaping of the mode profile can either contribute to or oppose the mode pushing, and even reverse it under appropriate conditions leading to a reduced scale factor in transmission. We demonstrate a method for further optimizing the transmission of both atom-cavity and coupled-cavity systems, but show that this leads to a more rectangular mode profile and a reduction in the scale factor bandwidth. We also derive the cavity scale factor in reflection for both atom-cavity and coupled cavity systems and show that in reflection the reshaping of the mode profile can either contribute to or oppose the mode pushing, but cannot reverse it.

We recently demonstrated optical pulses with large negative group velocities using a scheme based on four-wave-mixing in rubidium vapor. Both the probe and the generated conjugate pulses can experience anomalous dispersion, and we have demonstrated a maximum group advancement of 64% relative to the input pulse width. The four-wave-mixing scheme allows us to send whole images through a fast light medium, and we have analyzed the arrival of spatially-encoded information in the system. We are currently investigating the transport of quantum correlations that are shared by the probe and conjugate modes when sent through fast light media.

We report a comparative study on dephasing mechanisms between inner core coated and uncoated sections of the same Kagome hypocycloid-shaped core hollow core photonic crystal fibers (HC-PCF) filled with rubidium vapor. The comparison is performed by measuring the atomic polarization relaxation and electromagnetically induced transparency (EIT) linewidth in Rb loaded polydimethylsiloxane (PDMS) inner wall coated and bare silica core Kagome HC-PCF. The measurements show a polarization relaxation time of 32μs in a PDMS coated Kagome HC-PCF and 24μs in uncoated Kagome HC-PCF. A minimum EIT linewidth of 6.2±0.8MHz is achieved in PDMS coated Kagome HC-PCF, and 8.3±0.9 MHz for the uncoated Kagome HC-PCF.

We present theoretical and experimental results on a slow-light assisted all-fiber configuration that can be used for efficient sensing of a variety of parameters (pressure, displacement...). In particular, we report here a structure that can be transformed into a slow-light assisted displacement sensor capable of sub-micrometric resolution values with a potentially simple intensiometric measurement scheme. The basic element in the structure is a lossy ring resonator tuned close to the critical coupling regime. In this working regime, the resonator transfer function displays extremely high group delay values close to the resonances, and, accordingly, a large sensitivity to additional losses. A mechanic transducer transforms displacement into small additional losses in the ring. This leads to strong variations in the log transmission of the resonances, which are shown to scale with the group index. This scheme shows orders of magnitude sensitivity enhancements over a conventional bending-loss configuration. We believe that this structure can be further developed to provide large sensitivity enhancements to conventional intensiometric fiber sensors.

We report our progress towards a high performance solid-state ring laser gyro using a diode-pumped Nd-YAG crystal as the gain medium. We then discuss the possibility of including in this device a highly dispersive medium, which could serve for testing the recent proposal by Shariar and coworkers of a fast-light ring laser gyro. This discussion is supported in particular by the recent results obtained at Laboratoire Aimé Cotton with electromagnetically induced transparency in metastable helium

We present a comprehensive study of the properties of a superluminal fiber laser based super-sensor employing Brillouin gain. Exact analytical expression for the required parameters and the sensitivity enhancement are derived. The dependence of the sensitivity enhancement on the measured phase shift is found to be highly nonlinear, rapidly increasing at smaller quanta. The minimal detectable shift due to shot noise is found to be smaller by 8 orders of magnitudes compared to conventional laser sensors. The tradeoffs between the attainable sensitivity enhancement, the cavity dimensions and the impact of the cavity roundtrip loss are studied in details providing a set of design rules for the optimization of the super-sensor.

We propose a configuration consisting of several passive ring resonators named as fast-light enhanced ring resonator, coupled to an active ring laser for introducing anomalous dispersion. Theoretical analysis indicates that the introduced anomalous dispersion allows the frequency shift to be improved as large as one order of magnitude due to Sagnac effect when the structure is rotated, namely having the same rotational sensitivity compared to a standard ring-laser gyroscope (RLG) with tenfold size as that of the proposed structure. In this paper, the impact of passive ring resonator number is discussed and deduced, which manifests that only odd number of passive rings will produce effective anomalous dispersion, thus improve the rotational sensitivity. The configuration proposed here will have broad prospect in realizing highly integrated on-chip laser gyroscope for rotation sensing.

Lattice-shifted photonic crystal waveguides (LSPCWs) are effective for generating wide-band on-chip slow light at room temperature. In this study, we integrated the LSPCW with multi-heaters using CMOS-compatible process, and demonstrated electrically-tunable slow light. Seven heaters were placed on each side of the LSPCW with air slots for thermal isolation. On-demand temperature distributions were formed by controlling each heating power independently. When the heating powers were optimized, a clear delay peak of slow light corresponding to the flat photonic band of the LSPCW was observed, which suggests that fabrication errors in the air-hole diameters were less than 5 nm and related band fluctuation was well compensated by the heating. When a linear temperature distribution was added to this condition, the delay was reduced up to 54 ps. When a quadratic distribution was added, the group delay dispersion was generated in the range from -10.2 to 17.5 ps/nm. We applied the tunable delay to the delay scanning in optical correlator. Here, output pulse were compressed to 0.6 ps through self-phase modulation and dispersion compensation in external fibers, and its delay was tuned in range of 17 ps. At a scanning frequency of 100 Hz, which is <10 times faster than that of conventional mechanical delay scanners, pulse lengths of 0.3 - 6 ps were measured with a <95% accuracy. We are also fabricating all on-chip optical correlator consisting of this slow light delay scanner and two-photon-absorption photo-diodes.

We demonstrated ultrafast delay tuning of slow-light pulse with a response time < 10 ps. This is achieved using two types of slow light: dispersion-compensated slow light for the signal pulse; and low-dispersion slow light to enhance the nonlinear effect of the control pulse. These two slow light are generated simultaneously in lattice-shifted photonic crystal waveguides, arising from flat and straight sections of the photonic band, respectively. The control pulse blue-shifts the signal pulse spectrum, through dynamic tuning and cross-phase modulation caused by the plasma effect of two-photonabsorption carriers. This changes the delay by up to 10 ps only when the two pulses overlap within the waveguide, and enables an ultrafast tuning that is not limited by the carrier lifetime. Using this, we succeeded in the delay tuning of one target pulse within a pulse train with 12 ps intervals.

Quantum information can be transferred from a beam of light to a cloud of atoms and controllably released at a later time. This process forms the basis of many important quantum memory devices that are fundamental to the future of quantum information science, quantum computing, and quantum communication. Prior experiments have stored light in a variety of systems, including cold atom clouds, warm atomic vapor, solid state materials, and optical fibers. To extend these successful investigations, the goal of our research program is to carry out a full characterization of the quantum states of stored-and-retrieved multimode light.

Single photons are a vital resource for optical quantum information processing. Efficient and deterministic single photon sources do not yet exist, however. To date, experimental demonstrations of quantum processing primitives have been implemented using non-deterministic sources combined with heralding and/or postselection. Unfortunately, even for eight photons, the data rates are already so low as to make most experiments impracticable. It is well known that quantum memories, capable of storing photons until they are needed, are a potential solution to this `scaling catastrophe'. Here, we analyze in detail the benefits of quantum memories for producing multiphoton states, showing how the production rates can be enhanced by many orders of magnitude. We identify the quantity $eta B$ as the most important figure of merit in this connection, where $eta$ and $B$ are the efficiency and time-bandwidth product of the memories, respectively. We go on to review our progress in implementing the most broadband memory to date, with $B<1000$, in room-temperature cesium vapour. We consider the noise properties for single photon storage and the integration of the memory using waveguides.

We consider a free motion of a quantum particle. Introducing an explicit measurement procedure for velocity, we demonstrate that the measured velocity is related to the group and phase velocities of the corresponding matter waves. We show that for long distances the measured velocity coincides with the matter wave group velocity.

We investigate weak optical probe pulse propagation in a resonant Lambda and N-interaction schemes, and investigate the role of the four-wave mixing on classical and quantum properties of the probe field. In particular, we focus our attention on two configurations. In the first case we take into account the off-resonant coupling of the strong field to the signal field ground state. Such configuration is relevant for EIT-based slow light and quantum memory. In the second configuration the additional control field is derived from an independent laser, and it is tuned to a different optical resonance from the ones forming an original Lambda system. Such interaction scheme allows realization of tunable slow and fast light, and was considered with regards to enhancement of optical gyroscopes performance. We demonstrate that in both cases the four-wave mixing (FWM) has a profound effect on signal field group velocity and absorption profile, and may even lead to gain. We present both semi-classical and fully quantum treatments for propagation of both signal and newly generated Stokes fields that include accurate description of their quantum noise. In particular, we analyze the case of a quadrature-squeezed signal field, and demonstrate that vacuum fluctuations of the Stokes field couple into the signal field through the FWM process and degrades the squeezing. The severity of this degradation grows with optical depths of an atomic medium, setting an additional practical limits for the experiments.

We investigate the feasibility of realizing a superluminal ring laser with enhanced sensitivity by using the gain produced via double-Raman pumping in an inverted three-level system. If the laser cavity is tuned to the center between the two gain peaks produced in such a system, it is expected to experience an effective negative dispersion, which can be tuned to the condition necessary for enhancing the sensitivity of the laser frequency to a change in the cavity length. Using a model of two idealized, independent Lorentzian gains, we solve the laser equations to show the enhancement of sensitivity. We then extend our analysis to calculate the gain profile in a real lambda system. Unlike the idealized system mentioned above, where the dual gain peaks are modeled as two adjacent Lorentzians in a manner that ignores the relative coherence between the Raman pumps, we present a more accurate model where this coherence is not neglected. As such, the Hamiltonian remains time dependent after making the rotating wave transformation. Using an approximation --- valid for practical systems --- where higher order terms in the density matrix are neglected, we determine the gain experienced by a weak probe beam. Numerical techniques are needed to incorporate the resulting gain and dispersion profiles into the laser equation to determine accurately the behavior of the superluminal laser. This work will be carried out in the near future. Experimental realization of a superluminal laser based on this approach may prove to be easier than other approaches proposed previously.

We consider a moving ultra-dispersive medium and demonstrate the enhanced Fizeau effect due to dragging the light. We have shown that the enhanced Fizeau effect on a single atom in a cavity can be observed. It has been shown that the change of phase is sensitive to the motion the speed of the order of 10⁻¹⁵ cm/Hz^1/2 and for possible displacements as small as 10⁻¹⁷ cm/Hz^1/2. One of application can be the detection of weak forces exerted on a single atom. In particular, the Coriolis force as small as 10⁻⁴² N/Hz^1/2 can be detected that would provide opportunity to detect rotation with sensitivity 10⁻¹⁷ s⁻¹Hz^−1/2.

Controlling reflectivity optically over a wide range of frequency band can be of great demand technologically. In this paper we show how this can be realized using a Fabry-P´erot cavity filled with a three-level atomic gas. Furthermore, we employ both concepts of electromagnetic induced transparency EIT and the white light cavity which in turn play the essential rule to control the susceptibility of the atomic gas. Once the susceptibility is controlled, all one needs to do is to look for the satisfying resonance conditions that run over a wide range of frequencies, which results in a wide band optical switch.

An all-optical telecommunications network requires all-optical routers. These routers would be able to process optical signals directly, without the transformation to the electrical domain. Thus, optical routers have the potential to accelerate telecommunications, i.e. to enhance the data rate and to minimize the latency times. Furthermore, since the double transformation at each network node can be omitted, they could be able to reduce the energy consumption of telecommunications. Key elements of optical routers are optical buffers, which are able to store the optical packets prior to processing in order to avoid congestion. Therefore, many different concepts for the realization of optical buffers have been presented so far. Most of these can just store or delay on-off keyed (OOK) signals. However, in optical telecommunications advanced modulation formats will be increasingly used because they are able to improve the transmission properties and to take advantage of the capacity of optical fibers. Thus, advanced modulation formats can drastically increase the transmissible data rates. Most of these advanced formats modulate the carrier’s phase or are a combination of amplitude and phase modulation. Here the storage of amplitude and phase modulated data packets with the so called quasi-light-storage (QLS) method will be shown. The QLS relies on the time-bandwidth coherence of each signal. Thus, as long as the sampling theorem in the frequency domain is not violated, a distortion-free storage of optical data packets with a delay-bandwidth product (DBP) of several thousand bits is possible. Here we will discuss the applicability of the QLS method to advanced modulation formats and we show experimental results of the tunable alloptical storage of OOK modulated signals with a DBP of 160 bit and the storage of phase shift keyed signals with a DBP of 60 bits.

We show both theoretically and experimentally that the lifetime of an active semiconductor photonic crystal nanocavity is enhanced thanks to the combination of two cooperative effects: slow light propagation based on coherent-population-oscillation effect and optical bistability. In particular we develop an analytical analysis enabling us to clearly show the physical mechanisms producing the enhancement of the cavity lifetime.

The history of resonance photonic crystals started with the pursuit for control over spontaneous decay in a photonic bandgap structure. Initiated by Bykov in optics, it was however implemented for the first time in the microwave domain by Yablonovitch et al. in 1991. This prediction of suppression of spontaneous emission of photons by a two-level atom turned into enhancement of optical nonlinearities, optical soliton generation and transport, and addressable light localization that is due to both structure and optically active defect created inside the crystal. This article reviews both fundamental theoretical ideas in the resonance photonic crystal with defect inside and selected experimental developments in the sense that reflects interests and expertise of the author.