This PDF file contains the front matter associated with SPIE Proceedings Volume 8095, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

Plasmonic metamaterials form an exciting new class of engineered media that promise a range of important applications, such as subwavelength focusing, cloaking and slowing/stopping of light. At optical frequencies, using gain to overcome potentially not insignificant losses has recently emerged as a viable solution to ultralow-loss operation that may lead to next-generation active metamaterials. Here, we employ a Maxwell-Bloch methodology for the analysis of these gain-enhanced optical nanomaterials. The method allows us to study the dynamics of the coherent plasmon-gain interaction, nonlinear saturation, field enhancement as well as radiative and non-radiative damping such as tunnelling and F¨orster coupling. Using numerical pump-probe experiments on a double-fishnet metamaterial with dye-molecule inclusions we investigate the build-up of the inversion and the formation of the plasmonic modes in the low-Q fishnet cavity. We find that loss compensation occurs in the negative-refractiveindex regime and that, due to the loss compensation and the associated sharpening of the resonance, the real part of the refractive index of the metamaterial becomes more negative compared to the passive case. Furthermore, we investigate the behaviour of the metamaterial above the lasing threshold, and we identify the occurrence of a far-field lasing burst and gain depletion when higher dye densities are used. Our results provide deep insight into the internal processes that affect the macroscopic properties of active metamaterials. This could guide the development of amplifying and lasing plasmonic nanostructures.

In the recent past, there has been an increasing interest in coupling surface plasmon structures with detectors. There are three main reasons that this approach has been exciting. The first is due to the fact that plasmonic structures can incorporate enhanced functionality such as color, polarization and dynamic range in the pixel. The second is the enhancement of the near-field electromagnetic field, which can be exploited for enhanced absorption and photocurrent. Thirdly, the electromagnetic field can be concentrated to a deep-subwavelength region. If the absorber is placed at the field point of the concentrator, the signal to noise ratio and the speed of the detector can be dramatically increased. In this paper, we report on some of our results on the use of plasmonic structures with quantum dot focal plane arrays.

Periodic silicon nanostructures can be used for different kinds of gas sensors depending on the analyte concentration. First we present an optical gas sensor based on the classical non-dispersive infrared technique for ppm-concentration using ultra-compact photonic crystal gas cells. It is conceptually based on low group velocities inside a photonic crystal gas cell and anti-reflection layers coupling light into the device. Experimentally, an enhancement of the CO₂ infrared absorption by a factor of 2.6 to 3.5 as compared to an empty cell, due to slow light inside a 2D silicon photonic crystal gas cell, was observed; this is in excellent agreement with numerical simulations. In addition we report on silicon nanotip arrays, suitable for gas ionization in ion mobility microspectrometers (micro-IMS) having detection ranges in principle down to the ppt-range. Such instruments allow the detection of explosives, chemical warfare agents, and illicit drugs, e.g., at airports. We describe the fabrication process of large-scale-ordered nanotips with different tip shapes. Both silicon microstructures have been fabricated by photoelectrochemical etching of silicon.

We report the first demonstration of on-chip stimulated Brillouin scattering (SBS). SBS is characterized in a chalcogenide (As₂S₃) photonic chip where the measured Brillouin shift and full-width at half-maximum (FWHM) linewidth are 7.7 GHz and 34 MHz respectively. The measured Brillouin gain coefficient (g_B) is 0.715 x 10^-9 m/W, consistent with the theoretical estimate.

A theoretical investigation of the mode profiles, mode volumes and Q-factors of infiltrated slot nanobeam cavities is presented. General design principals are discussed. A gradual adjustment of the pore distance and pore diameter of the pores closest to the cavity leads to a considerable increase of the Q-factors. Surprisingly a maximum Q-factor of 100 000 is expected with a linear taper including only two pores. An estimate for the power threshold of optical bistable transmission behavior is given.

Nanocrystals with second harmonic response is a new class of nonlinear optical nanoprobes with dramatically different properties from fluorescent agents. Compared with two-photon fluorescence, second harmonic generation is an ultrafast, lossless, and coherent process. In particular, the absence of photobleaching and emission intermittency in the optical response of the second harmonic nanoparticles is likely to complement the fluorescent agents widely used today in many imaging applications. Furthermore, the coherent emission from the second harmonic generation process provides unique opportunities for the application of coherence domain techniques that are not available with fluorescent agents. We review the application of the second harmonic nanocrystals in imaging applications, especially those pertaining to biomedicine.

A dielectric medium with time-periodic permittivity ε(t) gives rise to a band structure that is periodic in the frequency ω and exhibits wave vector gaps ▵k. Light reflected from and transmitted by such a dynamic slab contains harmonics ω - nΩ (n = 0, ±1,...) where Ω is the modulation frequency. Also, giant resonances are obtained in the response for ω = nΩ/2 with odd n, provided that a certain condition is satisfied for the slab thickness. Further, we show that a dynamic medium can be realized by means of a low-pass transmission line with varactors whose capacitance is C(t) = a ε(t) and inductances L = a μ₀, a being the period.

Ultrafast optical switches are one of the crucial components in next generation all-optical communication networks. One promising candidate is the optical switch based on saturable intersubband (ISB) absorption in doped InGaAs/AlAs/AlAsSb coupled double quantum wells (CDQW). We employ the density matrix theory and modified optical Bloch equations with the relaxation-time approximation to simulate the time evolution of optical nonlinearities in quantum well (QW) structures. The absorption saturation characteristics are derived afterwards. The theoretical estimates are used to interpret the corresponding experimental results. Furthermore, several impact factors related to dynamic and saturation characteristics of the materials are discussed theoretically. The studies provide useful clues to optimize the QW material and device design.

We show that nonlinear optical structures involving a balanced gain-loss profile can act as optical diodes. This is made possible by exploiting the interplay between the fundamental symmetries of parity (P) and time (T), with optical nonlinear Kerr effects. This unidirectional propagation is demonstrated for the case of a PT -symmetric nonlinear coupler and a PT-symmetric Bragg grating.

We reveal a number of fundamentally important effects which underpin the key aspects of light propagation in photonic structures composed of coupled waveguides with loss and gain regions, which are designed as optical analogues of complex parity-time (or PT) symmetric potentials. We identify a generic nature of time-reversals in PT-symmetric optical couplers, which enables flexible control of all-optical switching and a realization of logic operations. We also show that light propagation in PT-symmetric structures can exhibit strongly nonlocal sensitivity to topology of a photonic structure. These results suggest new possibilities for shaping optical beams and pulses compared to conservative structures.

We present results on experiments and theoretical modelling of light scattering in complex photonic media consisting of dielectric nanowires. Numerical finite-element calculations are used to investigate the frequency response of the transmission pseudomodes and corresponding frequency correlation in a random slab. We discuss our experiments demonstrating a new, ultrafast regime of phase breaking in stongly scattering nanowire materials. The new phase breaking phenomenon opens up avenues for ultrafast control of random lasers, nanophotonic switches, and photon localization.

Lasing action in disordered media has been studied extensively in recent years and many of its properties are well understood. However, few studies have considered the spatial coherence in these systems, despite initial observations indicating that random lasers exhibit much lower spatial coherence than conventional lasers. We performed a systematic, experimental investigation of the spatial coherence of random laser emission as a function of the scattering mean free path and the excitation volume. Lasing was achieved under optical excitation and spatial coherence was characterized by imaging the emission spot onto a Young's double slit and collecting the interference fringes in the far field. We observed dramatic differences in the spatial coherence within our parameter space. Specifically, we found that samples with a shorter mean free path relative to the excitation volume exhibited reduced spatial coherence. We provide a qualitative explanation of our experimental observations in terms of the number of excited modes and their spatial orientation. This work provides a means to realize intense, spatially incoherent laser emission for applications in which speckle or spatial cross talk limits performance.

A diffusive theory of random lasing is derived for finite systems comprised of disordered arrays of laser active ZnO nanopillars. The diffusive transport of the light intensity is coupled to the semiclassical laser rate equations, therefore incorporating nonlinear optical gain in this effectively two dimensional system. We solve the resulting boundary condition problem to obtain the full spatial intensity profile of lasing spots in dependence of the pumprate and other system parameters. Our theory predicts two different types of random laser modes in effectively two dimensional systems in general. A surface mode with a large size extending over the entire sample width, and a bulk mode, with small laser spot sizes. We discuss their origin and characteristics.

The strong coupling between a mode confined in a dielectric waveguide and a surface plasmon was demonstrated. It was shown that the strong and weak coupling regime can coexist. The strong coupling allows the spatial exchange of energy and opens a way towards the quantum control of plasmon, i.e. quantum plasmonics.

High-performance and low-cost sensors are critical devices for high-throughput analyses of bio-samples in medical diagnoses and life sciences. In this paper, we demonstrate photonic crystal nanolaser sensor, which detects the adsorption of biomolecules from the lasing wavelength shift. It is a promising device, which balances a high sensitivity, high resolution, small size, easy integration, simple setup and low cost. In particular with a nanoslot structure, it achieves a super-sensitivity in protein sensing whose detection limit is three orders of magnitude lower than that of standard surface-plasmon-resonance sensors. Our investigations indicate that the nanoslot acts as a protein condenser powered by the optical gradient force, which arises from the strong localization of laser mode in the nanoslot.

We investigate the use of MOVPE-grown ordered nanostructures on non-planar substrates for quantum nano-photonics and quantum electrodynamics-based applications. The mastering of surface adatom fluxes on patterned GaAs substrates allows for forming nanostrucutres confining well-defined charge carrier states. An example given is the formation of quantum dot (QD) molecules tunneled-coupled by quantum wires (QWRs), in which both electron and hole states are hybridized. In addition, it is shown that the high degree of symmetry of QDs grown on patterned (111)B substrates makes them efficient entangled-photons emitters. Thanks to the optimal control over their position and emission wavelength, the fabricated nanostructures can be efficiently coupled to photonic nano-cavities. Low-threshold, optically pumped QWR laser incorporating photonic crystal (PhC) membrane cavities are demonstrated. Moreover, phononmediated coupling of QD exciton states to PhC cavities is observed. This approach should be useful for integrating more complex systems of QWRs and QDs for forming a variety of active nano-photonic structures.

Low power optical nonlinearities are a crucial requirement for data routing and next generation all-optical processing. The majority of nonlinear optical devices to date exploit weak nonlinearities from a large ensemble of atomic systems, resulting in both high power dissipation and a large device footprint. Quantum dots (QDs) coupled to photonic crystals can provide significant reduction in both device size and power dissipation. The interaction between these two systems creates extremely strong light-matter interaction owing to the tight optical confinement of photonic crystals and large oscillator strengths of QDs. Such interactions enable optical nonlinearities near the single photon level. In this work we investigate the nonlinear properties of QDs coupled to photonic crystals. We demonstrate large optical Stark shift with only 10 photons. We then propose and demonstrate a novel photonic circuit that can route light on a chip with extremely low optical powers.

Recently, photonic crystals have enabled a variety of ultrasmall photonic devices with extremely small energy consumption of ~fJ/bit level, suggesting that we can integrate a vast number of nanophotonic devices in a single chip. This technology may give us a way to introduce high-speed integrated nanophotonics in an information chip, which will be crucial in future ICT.

A fabrication procedure for electrically pumping photonic crystal membrane devices using a lateral p-i-n junction has been developed and is described in this work. The lateral junction is optimized to efficiently inject current into a photonic crystal nanocavity. We have demonstrated electrically pumped lasing by using the lateral junction to pump a quantum dot photonic crystal nanocavity laser. Continuous wave lasing is observed at temperatures up to 150K, and a threshold of 181nA at 50K is demonstrated - the lowest threshold ever demonstrated in an electrically pumped laser. We have demonstrated electrical pumping of photonic crystal nanobeam light emitting diodes, and observe linewidth narrowing at room temperature.

Controlling losses in metamaterials has now reached an advanced stage, so that building up a range of integrated waveguide devices based upon them is not only attractive from a fundamental point of view, but it is going to be possible to imagine a number of special down-stream applications. The degree of control obtained by manipulating planar metamaterial waveguides and interfaces is important and is popularly based upon solitons of various kinds. Complete control is assured by invoking transformation optics, as will be briefly demonstrated here.

Plasmonic devices, based on surface plasmons propagating at metal-dielectric interfaces, have shown the potential to manipulate light at deep subwavelength scales. One of the main challenges in plasmonics is achieving active control of optical signals. In this paper, we introduce active plasmonic devices enhanced by waveguide dispersion engineering. We consider plasmonic waveguide systems consisting of a metal-dielectric-metal waveguide (MDM) side-coupled to arrays of MDM stub resonators. The MDM waveguide and stubs are filled with an active material whose absorption coefficient can be modified with an external control beam. Such plasmonic waveguide systems can be engineered to support slowlight modes. We find that, as the slowdown factor increases, the sensitivity of the effective index of the mode to variations of the refractive index of the active material increases. Such slow-light enhancements of the sensitivity to refractive index variations lead to enhanced performance of active plasmonic devices such as switches. To demonstrate this, we consider absorption switches based on Fabry-Perot cavity structures, consisting of slow-light plasmonic waveguide systems sandwiched between two conventional MDM waveguides. We find that increased slowdown factor leads to increased induced change of the propagation length of the slow-light mode for a given refractive index variation, and therefore to increased modulation depth. Compared to conventional MDM absorption switches, slow-light enhanced switches achieve significantly higher modulation depth with moderate insertion loss. We use a scattering matrix theory to account for the behavior of the devices which is in excellent agreement with numerical results obtained with the finitedifference frequency-domain method.

A general overview of slow light waveguide structures made of negative metamaterials is presented. We discuss the conditions and the parameter space to achieve zero total energy flow and zero group velocity due to the degeneracy of forward and backward waves in waveguides cladded with single negative metamaterials. Absorptive loss plays a severely limiting role and can prevent achieving the zero group velocity condition. Gain can be introduced either in dielectric or negative metamaterials to restore the zero group velocity condition. This type of slow light waveguide has a large delay bandwidth product and is suitable for use in integrated optoelectronic circuits.

Mesoporous distributed Bragg re ectors (MDBRs) exhibit porosity on the sub-optical length scale. This makes them ideally suited as sensing platforms in biology and chemistry as well as for light management in optoelectronic devices. Here we present a new fast forward route for the fabrication of MDBRs which relies on the self-assembling properties of the block copolymer poly(isoprene-block-ethylene oxide) (PI-b-PEO) in combination with sol-gel chemistry. The interplay between structure directing organic host and co-assembled inorganic guest allows the ne tuning of refractive index in the outcome material. The refractive index dierence between the high and low porosity layer can be as high as 0.4, with the optical interfaces being well dened. Following a 30 min annealing protocol after each layer deposition enables the fast and reliable stacking of MDBRs which exhibit a continuous TiO₂ network with large accessible pores and high optical quality.

Thermal tuning of the transmission of an elastomer infilled photonic crystal cavity is studied. An elastomer has a thermal expansion-induced negative thermo-optic coefficient that leads to a strong decrease of the refractive index upon heating. This property makes elastomer highly suitable for thermal tuning of the transmission of a cavity, which is demonstrated by global infilling of a hole-type silicon photonic crystal slab and global thermal tuning. In the temperature range 20-60 ⁰C the cavity peak shows a pronounced elastomer-induced blue shift of 2.7 nm, which amply overcompensates the red shift arising from the thermo-optic property of the silicon. These results qualify the elastomer for tuning by local optical heating.

We investigate the mode of laser pulse propagation as in a homogeneous medium so in layered medium with the twophoton absorption at which the shape of pulse is self-similar along some distance of the propagation. Finding of the laser pulse shape with such property is based on the solution of nonlinear eigenfunction problem for Schrödinger equation with nonlinear absorption. Under certain conditions this eigenfunction gives us the pulse shape with requiring properties. This eigenfunction is considered as a spatial distribution of function for the nonlinear Schrödinger equation which contains the term describing the two-photon absorption. We have found out that the self-similar shape of pulse in a medium with the two-photon absorption is similar to the laser soliton at its propagation in a medium with Kerr nonlinearity. Nevertheless, the duration of self-similar pulse propagating in the homogeneous medium is less in comparison with the soliton duration for Kerr medium. The other difference between self-similar shape of pulse and soliton concludes in existence of mode of the self-similar shape of pulse only on limited distance of the optical pulse propagation. We show the reason of this evolution of the laser pulse. We see some applications of such mode of the laser pulse propagation. First, it is important for the laser pulse propagation in an active medium: obviously, the self-similar mode of laser pulse propagation may take place. Second, at a formation of TW or PW laser pulse with wide aperture on the base of non-linear compression of laser pulse in glass the two-photon (or three-photon) absorption occurs. Hence, the self-similar shape of pulse plays an essential role for practical problems.

We investigate the phenomena, which are similar to effects of the quantum teleportation and of superluminality, at the two-wave interaction in a medium with the quadratic and cubic nonlinear responses taking place simultaneously. The interaction of two femtosecond tosecond pulses occurs under the conditions of a group velocity mismatch. The formation of sub-pulses at both frequencies, part of which demonstrate soliton properties with a velocity higher or lower than the velocity of linear pulse propagation in considering condition at the same group velocity dispersion, is revealed. The reason of an acceleration of the sub-pulse is the induced periodic grating o dielectric permittivity. Consequently, the acceleration of the light pulse is due to tunneling through these gratings. It is very important that the gratings are absent before the interaction of laser radiation with the medium. The second important feature is the following. For each fast sub-pulse there is a pulse whose velocity is smaller than the velocity of the linear propagation. Hence, the preservation of an impulse of whole pulse takes place. The interesting property of the formed structures is the sensitivity of each of the anomalously propagating sub-pulses to perturbation introduced in the other sub-pulse at a chosen cross section. Another sub-pulse changes instantaneously at the perturbation of the given sub-pulse. This is similar to the effect of the quantum teleportation.