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The Winter Colloquium on the Physics of Quantum Electronics (PQE) has been a seminal force in quantum optics and related areas since 1971. It is rather mind-boggling to recognize how the concepts presented at these conferences have transformed scientific understanding and human society. In January 2017, the participants of PQE were asked to consider the equally important prospects for the future, and to formulate a set of questions representing some of the greatest aspirations in this broad field. The result is this multi-authored paper, in which many of the world’s leading experts address the following fundamental questions: (1) What is the future of gravitational wave astronomy? (2) Are there new quantum phases of matter away from equilibrium that can be found and exploited - such as the time crystal? (3) Quantum theory in uncharted territory: What can we learn? (4) What are the ultimate limits for laser photon energies? (5) What are the ultimate limits to temporal, spatial and optical resolution? (6) What novel roles will atoms play in technology? (7) What applications lie ahead for nitrogen-vacancy centres in diamond? (8) What is the future of quantum coherence, squeezing and entanglement for enhanced super-resolution and sensing? (9) How can we solve (some of) humanity’s biggest problems through new quantum technologies? (10) What new understanding of materials and biological molecules will result from their dynamical characterization with free-electron lasers? (11) What new technologies and fundamental discoveries might quantum optics achieve by the end of this century? (12) What novel topological structures can be created and employed in quantum optics? [ABSTRACT FROM AUTHOR]

The photonic crystals draw significant attention to build all-optical logic devices and are considered one of the solutions for the opto-electronic bottleneck via speed and size. The paper presents a novel optical 4 × 2 encoder based on 2D square lattice photonic crystals of silicon rods. The main realization of optical encoder is based on the photonic crystal ring resonator NOR gates. The proposed structure has four logic input ports, two output ports, and two bias input port. The photonic crystal structure has a square lattice of silicon rods with a refractive index of 3.39 in air. The structure has lattice constant ‘a’ equal to 630 nm and bandgap range from 0.32 to 044. The total size of the proposed 4 × 2 encoder is equal to 35 μm × 35 μm. The simulation results using the dimensional finite difference time domain and Plane Wave Expansion methods confirm the operation and the feasibility of the proposed optical encoder for ultrafast optical digital circuits. [ABSTRACT FROM PUBLISHER]

Imaging characteristics of germanium cylinder-based decagonal photonic quasicrystal flat lens have been analyzed with respect to width. The results show that the complex near-field scattering effects and the short-range interactions do not determine the occurrence of the imaging phenomenon but affect imaging characteristics. Changing the width will affect the imaging characteristics of the flat lens. As the width increases, the image power, the image quality, and the summed object–image distance change non-monotonically but stabilize gradually. [ABSTRACT FROM PUBLISHER]

Single-pixel imaging has emerged a decade ago as an imaging technique that exploits the theory of compressive sensing. In this research, the problem of optimizing the measurement matrix in compressive sensing framework was addressed. Thus far, random measurement matrices are widely used because they provide small coherence. However, recent reports claim that measurement matrix can be optimized, thereby improving its performance. Based on such proposition, this study proposed an alternative approach of optimizing the measurement matrix in a hierarchical model. In particular, this study constructed the hierarchical model based on an increasing resolution grade by exploiting the guided information and the adaptive step size method. An image with a demanded resolution was then obtained using the l1-norm method. Subsequently, the performance of the introduced method was verified and compared with those of existing approaches via several experiments. Results of the tests indicated that the reconstruction quality of optimizing the measurement matrix was improved when the proposed method was used. [ABSTRACT FROM PUBLISHER]

A compact crossing scheme for a silicon-based slot-to-strip (or vice versa) waveguide is proposed and analyzed by using a finite-difference time-domain method, where a strip–multimode waveguide (SMW) crossing is used at the center and two logarithmically tapered slot-to-strip mode converters are incorporated into the ports with slot waveguides. For the input ports with slot waveguides and output ports with strip waveguides, the guided modes are efficiently transformed through the mode converter, and then enter into the SMW, where the fields converge at the center of the intersection due to the self-imaging effect. Hence, the size of the input beam is much smaller than the width of the SMW at the crossing center, leading to significant reductions of both crosstalk and radiation loss. The numerical results show that a slot-to-strip waveguide crossing operating at a wavelength of 1.55??m can be achieved with insertion loss, crosstalk, and reflection of 0.134/0.182, ?36.18/?38.6, and ?35.8/?42.02?dB for input ports with slot/strip waveguides, respectively. [ABSTRACT FROM PUBLISHER]

A numerical study is reported of the propagation of an initially localized wave in a one-dimensional disordered lattice composed of left-handed metamaterials. We first consider the structure made of right-handed and left-handed materials arranged periodically. By allowing disorder in the refractive index of the right-handed materials, the injected wave becomes localized as propagating through the disordered lattice. Then, we consider another photonic lattice comprising only left-handed metamaterials. It is found that the inclusion of disorder in the negative refractive index of the constituents of the system leads to transverse Anderson localization. We also investigate the dispersion effect of metamaterials on the localization behavior. It is demonstrated that inclusion of a dispersive metamaterial in the disordered photonic lattices causes the quality of transverse localization to enhance with increasing wavelength. [ABSTRACT FROM PUBLISHER]

The boundary integral equation method (BIM) was one of the first methods in grating theory. It has been used for the investigation of diffraction gratings of extremely different kinds as well as for photonic crystal diffraction gratings. Besides an overview of three of the most important BIMs for in-plane diffraction, we present a new BIM for gratings in a conical mounting with one profile as well as for separated multilayer gratings with photonics inclusions using a common description for both approaches. In numerical examples, (1) blazing in conical mounting is demonstrated at a photonic crystal diffraction grating, (2) the excellent conical efficiency convergence for a plasmonic structure of two stacked silver rod gratings is shown, and (3) the transmission for conical incidence is studied at a blazed grating with large period-to-wavelength ratio. [ABSTRACT FROM AUTHOR]

Photonics is a promising architecture for the realisation of quantum information processing, since the two-photon interaction, or non-linearity, necessary to build logical gates can efficiently be realised by the use of interference with ancillary photons and detection 1. Although single-photon sources and detectors are pivotal in realisations of such systems, clear guidelines for the required performance of realistic systems are yet to be defined. We present our detailed numerical simulation of several quantum optics circuits including sources and detectors all represented in multi-dimensional Fock-spaces, which allows us to obtain experimentally realistic performance bounds for these devices. In addition, the single-photon source based on switched parametric down-conversion is studied, which in principle could reach the required performance. Three approaches for implementing the switching hierarchy of the photons are simulated, and their anticipated performance is obtained. Our results define the bar for the optical devices needed to achieve the first level of linear-optics quantum computing outside the coincidence basis. [ABSTRACT FROM AUTHOR]

This paper presents our recent results on the materials science and engineering research that we are pursuing for what we call very large scale integrated (VLSI) micro/nano-photonic circuit applications and optical printed circuit board (O-PCB) applications. It discusses on the design and fabrication of optical waveguides and photonic devices to be part of the micro/nano-photonic integration for VLSI photonic integrated circuits of generic and application-specific nature. The optical circuits consist of 2-dimensional planar arrays of micro/nano-optical wires, circuits and devices to perform various functions. The integrated optical circuits are primarily made of polymer and silicon materials. We present the use of organic-inorganic hybrid materials for micro-scale optical waveguide fabrication and discuss various attempts to vary the optical properties such as refractive indices, transmission windows, losses, birefringence, dispersion, nonlinearity, thermal/mechanical stability, and related issues. These waveguides and devices are considered particularly useful for O-PCB fabrication. We then present the use of silicon as a basic material for VLSI photonic devices. We discuss their properties and advantages for nano-scale functional waveguides and devices for VLSI photonics. We will look into the use of silicon materials as the basis for the building blocks of VLSI photonics. We will finally discuss the issues regarding how these building blocks can be put together for integration for O-PCB and VLSI photonic chips. [ABSTRACT FROM AUTHOR]

The article offers information on high speed photography and photonics. The four regions of high speed photography based on the definition contained in the "Focal Encyclopedia of Photography" are presented. It traces the history the evolution of high speed still and cine photography. The development of roll film is explored. It explains the sources of light in photography. Also noted are the benefits and applications of high speed photography.

We propose the design of broadband optical reflector using a one-dimensional graded photonic crystal (GPC) structure. The proposed structure consists of a periodic array of two alternate layers of SiO2 and Si with low and high values of refractive indices (n1 and n2) and thicknesses a and b, respectively. The GPC structure considered here has a linear change in the thickness of the constituent layers for a certain number of layers and has a periodic repetition of this unit. In order to calculate the reflection properties a transfer matrix method (TMM) has been used. This investigation shows that GPC structures have wider reflection bands in comparison to a conventional PC structure and the width of the reflection bands can be enlarged by increasing the number of graded periods and also by increasing the thickness of periods. We also observe that in a GPC structure, omnidirectional reflection (ODR) bands get enhanced without increasing the number of layers of the structure. Hence, a GPC structure can be used as a broadband optical reflector and the range of reflection can be tuned to any wavelength region by varying the thickness of the graded periods. [ABSTRACT FROM AUTHOR]

General properties of solid core photonic bandgap fibers are presented as well as general guidelines, found thanks to numerical investigations, helpful for designing this kind of fibers. We give two examples of applications and a new fiber design with interstitial air holes that lead to a significant reduction of both confinement and bend losses. This design allows the light to be guided in the fiber core thanks to a modified total internal reflection mechanism at long wavelengths and by photonic bandgap at short wavelengths. Furthermore, this new design satisfies the phase index matching condition for either second- or third-harmonic generation between two fundamental modes. [ABSTRACT FROM AUTHOR]

A novel design of a microwave photonic filter with infinite impulse response is demonstrated. The design is based on a dual drive modulator with an optoelectronic feedback loop. The stopband of the filter can be switched to passband and vice versa by switching the bias point of the dual drive modulator. Measured results confirm the theoretical expressions and demonstrate a rejection ratio and frequency selectivity which is greater than 30 dB. [ABSTRACT FROM AUTHOR]

The noise figure and sub-octave spurious-free dynamic range of a carrier-suppressed analog RF photonic link are examined. Expressions for noise figure and dynamic range are derived as a function of the modulator bias angle. A closed form expression for the bias angle that optimizes link noise figure and spurious-free dynamic range is also derived. Experimental results are presented and shown to agree with calculations. These experimental results include some of the lowest noise figure and highest dynamic range results published to date for an RF photonic link incorporating a standard Mach-Zehnder modulator: 6 dB and 122 dB·Hz2/3, respectively. [ABSTRACT FROM AUTHOR]

A two-dimensional, square-lattice photonic crystal model possessing analytical solutions is investigated to ascertain the requirements for negative refraction to occur. The refraction properties are presented for both polarizations assuming in-plane propagation and phase matching conditions across a surface perpendicular to the ΓM-direction of the crystal. It is shown that the most isotropic and highest effective refractive index is obtained near the maximum of the lowest band for a crystal with a high refractive index contrast between its constituent materials. [ABSTRACT FROM AUTHOR]

We present the results of experimental and theoretical studies that demonstrate the feasibility of realizing electro-optical switching, frequency filtering and negative index of refraction. In liquid crystal infiltrated TiO 2 inverse opal 3-D photonic crystals, we observed a sizeable electrical tuning of the Bragg reflection peak. In frequency selective structures with a liquid crystal over-layer, the tuning range can be as wide as 380 nm, operational throughout the entire visible – far infrared spectra range. Furthermore, some of the structures can be designed to exhibit a negative index of refraction property over a predetermined frequency interval. [ABSTRACT FROM AUTHOR]

In this article, we give out the formulations of the fields in a three-layer fiber. For a typical step-index single-mode fiber, we calculate propagation constants and mode field profiles of the cladding modes in it. Results show that the hybrid cladding modes, whose azimuthal quantum number is not zero, can also be rigorously divided into HE and EH modes. Comparison with the results of the two-layer geometry approximation indicates that when solving the cladding modes in a fiber the simplified model is unsuitable. [ABSTRACT FROM AUTHOR]

We successfully simulated the 10 × 40 Gbit/s soliton RZ-DPSK WDM signals over 1050 km with spectral efficiency approaching 0.4 bit/s/Hz using semiconductor optical amplifiers (SOAs) as in-line amplifier. The cross-gain saturation of SOA can be minimized by settling crosstalk at a lower level by decreasing the differential gain. This decrease in differential gain is in such a way that we get nil power penalty. The maximum transmission distance of 1050 km is possible with differential gain 210 atto cm 2 of SOA. The impact of amplification factor, ASE noise power, crosstalk, quality factor and bit error rate for different differential gain has been investigated. It has been shown that with the increase in differential gain of SOA, the transmission distance goes on decreasing. At high value of differential gain 2.5 × 10 -16 cm 2 for the transmission distance 1050 km, all channels produce inter channel crosstalk with bit error rate greater than 10 -6 . But for lower differential gain 190 atto cm 2 , the quality of all channel increases at the cost of large power penalty. With slight increase in differential gain 200 atto cm 2 , the maximum transmission distance observed is 4550 km with quality of received signal more than 15 dB and having nil power penalty. We observed clear eye diagrams and optical power spectra for received signal with transmission distance 1050 km and 4550 km using soliton RZ-DPSK system. The bit error rate for all channels increase more than 10 -10 with the increase in launched input power that is due to power saturation. [ABSTRACT FROM AUTHOR]

The bandstructures of two-dimensional photonic crystals with octagonal quasicrystalline unit cells have been calculated. The existence of photonic band-gaps in such structures is demonstrated, and results showing the variation of the spectral position and width of the photonic band-gaps with the size of the unit cell and filling fraction within the unit cell are presented. [ABSTRACT FROM AUTHOR]

Two novel wide-angle and broadband 2D photonic crystal polarization splitters (PCPS) which are the multilayer wavy films (MWF) structure and arrow-head like structure are designed based on the autocloning method. Plane wave expansion (PWE) method is used to calculate the band structure and explain the reason for the wide-angle and broadband polarization splitting effect. In order to verify the result derived from PWE method, finite-difference time-domain (FDTD) method is employed to test and measure the polarization effect for the MWF structure. [ABSTRACT FROM AUTHOR]

We generate high-dimensional time-bin entanglement using a mode-locked laser and analyse it with a two-photon Fabry–Perot interferometer. The dimension of the entangled state is limited only by the phase coherence between subsequent pulses and is practically infinite. In our experiment a picosecond mode-locked laser at 532 nm pumps a non-linear potassium niobate crystal to produce photon pairs by spontaneous parametric down-conversion (SPDC) at 810 and 1550  nm. [ABSTRACT FROM AUTHOR]

The stimulation and detection of both the A - and E -symmetry Raman lines in α-quartz using ultrafast impulsive stimulated Raman scattering is presented. Using a flexible experimental set-up, each nuclear oscillatory mode is selected and analysed in the time domain separately. The mode selection is made possible with optical summing of the fields involved to reduce noise and assure accurate synchronization. The experimental procedure is compared to optical heterodyne detection Raman-induced Kerr effect spectroscopy (OHD-RIKES) and the data is compared with standard frequency-domain measurements. [ABSTRACT FROM AUTHOR]

In this paper, a band-stop radiation filter based upon a planar photonic crystal single-defect micro-cavity is studied. The micro-cavity is located within a photonic crystal region and fed by a ridge waveguide. Because the micro-cavity structure is bounded on one side by a limited number of crystal rows, there is strong radiation, at resonance, into the surrounding 2D slab (i.e., the region that is free from the photonic crystal). The antenna radiation pattern of this micro-cavity can be substantially directional and is strongly dependent upon the cavity resonant wavelength, giving the possibility for this device to act as a directional radiation filter. The theoretical analysis of this device is performed by using 2D Finite-Difference Time-Domain (FDTD) methods, while the device is fabricated in an InP epi-layered structure. Initial characterization results are also presented for this single-defect radiation filter. [ABSTRACT FROM AUTHOR]

We demonstrate a long-term continuous readout of a two-dimensional image in a photorefractive holographic memory with a BaTiO3 crystal. A considerable extension of reading time is achieved by use of a hologram sustainment technique with an optical feedback circuit. Hologram rewritings by the simultaneous illumination of the reading beam and the feedback beam, which is incident on a crystal from the opposite direction to the reading beam, contribute to all-optical hologram sustainment without any fixing technique. In this paper, the effectiveness of the hologram sustainment technique is explained by the analysis of the temporal property of the amplitude of the index grating in a crystal. By calculating the temporal properties of the reconstructed beam intensity, we reveal the feedback rate and the coupling strength for high output efficiency. We perform an experiment on two-dimensional image reading and writing with a 45° cut BaTiO3 crystal and show that a recorded image can be reconstructed over 20?min without critical image degradation whereas a reconstructed image fades away within 20?s in the conventional readout technique. [ABSTRACT FROM AUTHOR]

Photochromic and acidochromic properties of dithienylethene-indolino[2,1-b]oxazolidine dyads and triads along with their reduced forms were investigated. Upon protonation the p-conjugated system is greatly increased. The resulting acidoinduced indoleninium species deeply influence the maxima absorption of the dithienylethene subunits whose maxima for the closed forms is red-shifted to the infrared region. These examples constitute a promising approach towards multiaddressable molecular switches based on diarylethenes. [ABSTRACT FROM AUTHOR]

A new theoretical model based on the standard-model equations but ensuring conservation of energy by accounting for the optical powers stored in the laser cavity is presented. This model succeeds in grouping two sorts of previous models: those based on standard equations and those based on conservation of number of photons. Furthermore, it provides a more complete quantitative description of EDSFLs (erbium-doped silica fibre lasers) and also improves the qualitative description of these devices by including the spontaneous emission terms and by determining the optical powers involved as well as the oscillation wavelength. The possibility of solving the EDSFL system including the power modal distribution within the fibre is also considered. Finally, a detailed comparison between this model and the models proposed by other authors is shown, where it is proved that the new model describes much better the behaviour of EDSFLs. [ABSTRACT FROM AUTHOR]

In this article, the simulation results have been presented for dispersive optical communication with different electrical drivers. The length of single-mode fiber has been put in a run that is compensated by dispersion-compensated fiber. The results have been presented and it is observed that of all the electrical drivers, the NRZ rectangular is best suited for dispersive optical communication systems. For this electrical driver, the parameters like BER remain constant and tow. For other drivers, the RER decreases more for RZ super-Gaussian. Similarly, the Q factor increases with runs for all types of drivers except for NRZ rectangular, for which it decreases. For all the drivers, it is clear that as the runs are varied, the eye opening penalty increases, that is, there is eye opening as the length of single-mode fiber is increased. It is also seen that the dispersion-compensated fiber compensates for the dispersion very effectively irrespective of the type of driver. Of the two formats, return to zero (RZ) and non-return to zero (NRZ), the earlier has more eye-opening penalty as the distortion is more and is clearly visible in all the rectangular, super-Gaussian, and raised cosine RZ formats. Of the three RZ formats, it is observed that RZ rectangular has the least eye-opening penalty. The non-return to zero format has less distortion and, of the two rectangular and raised cosine, the NRZ rectangular has less eye-opening penalty. [ABSTRACT FROM AUTHOR]

We have fabricated tapered photonic crystal fibers using a fusion splicer and experimentally observed the near-field mode distribution and the beam divergence of it. We have also compared characteristics of the tapered photonic crystal fiber with those of a tapered standard single-mode fiber. Unlike a tapered standard single-mode fiber, the mode field profile of a tapered photonic crystal fiber shows a good confinement of its field within the core region. The numerical apertures of tapered photonic crystal fibers are increased as the diameter of the fiber is decreased. [ABSTRACT FROM AUTHOR]

The coupling of light from a number of few or single-moded fibers into a single multi-mode fiber is analyzed using geometric optics, and simple results demonstrating mode conservation are derived. Coupling from multiple single-mode fibers into a multi-mode fiber is investigated in detail using the overlap integral to determine coupling into each mode of the output fiber as a function of the light phase in the inputs. As well as results with practical relevance to fiber tapped delay-line filters and optical CDMA, the analysis provides pedagogic insight into light propagation and the light-gathering properties of fiber. [ABSTRACT FROM AUTHOR]

This paper presents some examples of emerging opportunities at the interface of photonics, nanotechnology and biotechnology. The examples provided here are in the areas of bioimaging for optical diagnostics and nanomedicine, and they are taken from the work conducted under a multidisciplinary program at our Institute for Lasers, Photonics and Biophotonics. [ABSTRACT FROM AUTHOR]

The recent research and development results of the Photonic Engineering Group in the photonic sensing field are reported. This article includes a sample of contributions in several of the ongoing R&D lines: fiber sensing using Bragg grating technology; gas sensing, high temperature monitoring; optoelectronic instrumentation for laser welding monitoring; fiber active devices; and, finally, on sensing technology using plastic optical fiber. [ABSTRACT FROM AUTHOR]

The use of novel nanostructured materials for optical applications continues to be an important issue for the creation of new devices. New materials including metal nanoparticles have played an important role for applications in photonics, biology, as well as medicine. This review primarily concerns the use of one particular metal nanoparticle topology, dendrimer-metal nanocomposites. The focus of this review is to describe the optical properties of dendrimer-metal nanocomposites as well as functionalized dendrimer-metal nanocomposites. The description of various synthetic methodologies to produce transition metal (Au, Ag, Pd, Pt, and Cu) dendrimer nanocomposites as well as lanthanide ion-cored dendrimers are presented in this review, with further details regarding the basic characterization of these systems. The experimental procedures of the optical measurements used to probe the steady-state and time-resolved dynamics in these novel nanoparticle architectures are provided. Analysis of optical properties of dendrimer nanocomposites (DNCs) includes a description of the characterization of the metal nanoparticles as well as the size and distribution of metal nanoparticles formed by use of organic dendrimer template synthetic procedures (such as PAMAM). The non-linear transmission properties of certain dendrimer-metal nanocomposites show promising behaviour, which may be useful for applications involving eye and sensor protection. Reports of non-linear transmission properties of both Au and Ag dendrimer nanocomposites are discussed. Metal nanoparticles have also been suggested as useful materials for biological fluorescence imaging and sensing applications. However, it is well known that the efficiency of metal emission is very small. Recent measurements using ultra-fast spectroscopic techniques (fluorescence upconversion) have shed new light on this matter in metal nanoparticles and in dendrimer-metal nanocomposites. Dendrimer-metal nanocomposites have been used to investigate the dynamics of both metal particle emission and the interaction of metal particles with dipolar chromophores. The measurement and mechanism of ultra-fast transient absorption and emission dynamics in metal topologies including dendrimer nanocomposites are also discussed in the review. Future directions regarding the optical properties of dendrimer nanocomposites in the areas of photonics, biology, and medicine are also discussed in this review. [ABSTRACT FROM AUTHOR]

The synthesis of chiral nonracemic materials and the polarization properties of chiral optical waveguides fabricated from them are presented. These materials are based on binaphthyl compounds designed to produce a glassy isotropic optically active material in a thin solid film form. Chiral-core optical waveguides may find use as novel elements in integrated optic devices for photonics applications. [ABSTRACT FROM AUTHOR]

Nanofabrication offers promise for the design of artificial materials with optical properties unlike those of materials occurring in nature and for the design of new and exotic optical devices. We describe some specific ideas for applications in this area, and present some laboratory results on the development of these applications. [ABSTRACT FROM AUTHOR]

A simplified and very effective equivalent network model of a one dimensional Photonic Band Gap (ID-PBG) microstrip line for the harmonic tuning of Active Integrated Antenna (AIA) amplifiers is proposed in this paper. A parametric analysis of the transmission line reflection and transmission features is also presented showing the dependence of the stopband characteristics on the main geometrical parameters. Finally, the main effects of the proposed PBG filter in an AIA amplifier design are pointed out including harmonic tuning and output power increase. [ABSTRACT FROM AUTHOR]

A correlation between the line-width in super-resolved fluorescence microscopy and nonlinear optical theory used for polydiacetylene crystal-film is discussed. [ABSTRACT FROM AUTHOR]