Accepted papers to appear in an upcoming issue
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Electromagnetically induced grating in the microwave driven four level atomic systems
- received 09/11/2014; accepted 11/21/2014; posted 11/21/2014; Doc. ID 222677
- [full text: PDF (974) KB)]
- Abstract: A new scheme to investigate an electromagnetically induced grating in a N-type configuration in the presence of a strong standing coupling field, additional coherent fields and microwave driven field is presented. By considering Coherent Population Trapping (CPT) condition in a four level microwave driven N-type atomic system, a novel nonlinear optical storage is obtained via linear absorption vanishing and giant Kerr nonlinearity during light propagation. It is revealed that nonlinear properties in this atomic medium are maximum in the CPT condition, and these nonlinear properties could be affected and modulated by means of microwave driven field. In this condition, high phase modulated diffraction efficiency is attained. The diffraction pattern is sensitive to variables of the phase and amplitude of microwave field, consequently one can control the efficiency of different orders of grating more conveniently. The first-order diffraction efficiency of the grating about 45% can be obtained via choosing optimum values for phase and amplitude of microwave field. It is shown that the phase and modulation grating could be controlled effectively by atom-field radiation parameters such as interaction length L of atomic sample and applied filed detunings. It is noticed that a novel fast communication device could be obtained at the zero absorption point and on the superluminal light level.
- (050.0050) Diffraction and gratings : Diffraction and gratings
- (050.1940) Diffraction and gratings : Diffraction
- (050.1950) Diffraction and gratings : Diffraction gratings
- (190.0190) Nonlinear optics : Nonlinear optics
- (190.4400) Nonlinear optics : Nonlinear optics, materials
- (190.2055) Nonlinear optics : Dynamic gratings
Three-dimensional (3D) facial recognition using passive LWIR polarimetric imaging
- received 10/07/2014; accepted 11/21/2014; posted 11/21/2014; Doc. ID 224226
- [full text: PDF (1226) KB)]
- Abstract: We use a polarimetric camera to record the Stokes parameters and the degree-of-linear polarization of long-wavelength infrared (LWIR) radiation emitted by human faces. These Stokes images are combined with Fresnel relations to extract a surface normal. The surface normal is integrated to yield a three-dimensional facial image. One major difficulty of this technique is that the normal vectors determined from the polarizations are not unique. We overcome this problem by introducing an additional boundary condition on the subject. The major sources of error in producing inversions is noise in the images caused by scattering of the background signal and the ambiguity in determining the surface normals from the Fresnel coefficients.
- (110.6820) Imaging systems : Thermal imaging
- (110.6880) Imaging systems : Three-dimensional image acquisition
- (260.5430) Physical optics : Polarization
Secure Chaotic Transmission of ECG Signals with Acousto- Optic Modulation under Profiled Beam Propagation
- received 09/25/2014; accepted 11/20/2014; posted 11/20/2014; Doc. ID 223854
- [full text: PDF (595) KB)]
- Abstract: Electrocardiography (ECG) signals are used for both medical purposes and for identifying individuals. It is often necessary to encrypt this highly sensitive information before it is transmitted over any channel. A closed-loop acousto-optic hybrid device, acting as a chaotic modulator, is applied to ECG signals to achieve this encryption. Recently, improved modeling of this approach using profiled optical beams has shown it to be very sensitive to key parameters that characterize the encryption and decryption process, showing its potential for secure transmission of analog and digital signals. Here, the encryption and decryption is demonstrated for ECG signals, both analog and digital versions, illustrating strong encryption without significant distortion. Performance analysis pertinent to both analog and digital transmission of the ECG waveform is also carried out using output signal-to-noise (SNR), signal-to-distortion (SDR) and bit-error-rate (BER) measures relative to the key parameters and presence of channel noise in the system.
- (060.4080) Fiber optics and optical communications : Modulation
- (140.1540) Lasers and laser optics : Chaos
- (170.1065) Medical optics and biotechnology : Acousto-optics
- (060.4785) Fiber optics and optical communications : Optical security and encryption
Spectral shaping of all-fiber torsional acousto-optic tunable filter
- received 10/13/2014; accepted 11/20/2014; posted 11/20/2014; Doc. ID 224946
- [full text: PDF (679) KB)]
- Abstract: Spectral shaping of an all-fiber torsional acousto-optic (AO) tunable filter is studied. The technique is based on the axial modulation of AO coupling strength along a highly birefringent optical fiber, which is achieved by tailoring outer diameter of the fiber along its propagation axis. Two kinds of filter spectral shaping schemes – Gaussian apodization and the matched filtering with triple resonance peaks – are proposed and numerically investigated under the realistic experimental conditions: the 50-cm-long AO interaction length of the fiber and the half of original fiber diameter as the minimum thickness of tailored fiber section. The results show that the highest peak of sidelobe spectra in filter transmission is suppressed from 11.64% to 0.54% via Gaussian modulation of the AO coupling coefficient (κ). Matched filtering with triple resonance peaks operating with a single radio-frequency signal is also achieved by cosine modulation of κ, of which modulation period determines the spectral distance between two satellite peaks located in both wings of the main resonance peak. The splitting of two satellite peaks in the filter spectra reaches 48.2 nm while the modulation period varies from 7.7 to 50 cm. The overall peak power of two satellite resonances is calculated to 22% of the main resonance power. The results confirm the validity and practicality of our approach, and predict a robust and stable operation of the designed all-fiber torsional AO filters.
- (060.2310) Fiber optics and optical communications : Fiber optics
- (230.1040) Optical devices : Acousto-optical devices
Spectral measurement of birefringence using particle swarm optimization analysis
- received 07/14/2014; accepted 11/20/2014; posted 11/21/2014; Doc. ID 216918
- [full text: PDF (1720) KB)]
- Abstract: The measurement of the birefringence is useful for examination both technical and biological objects. One of the main problems is, that the polarization state of light in birefringent media changes periodically. Without knowledge of the period number, birefringence cannot be determined reliably. We propose to analyze spectrum of light in order to determine the birefringence. We use a Particle Swarm Optimization algorithm for automatic processing spectra of light transmitted through birefringent material for two orthogonal states of polarization. We have tested described algorithm on a liquid crystal cell with varying effective birefringence. The proposed method can be used for measurement of birefringence without knowing number of retardation period or approximate value of measurement result. It makes it useful for automatic measurements, when hundreds or thousands of spectra need to be analyzed.
- (120.5410) Instrumentation, measurement, and metrology : Polarimetry
- (160.3710) Materials : Liquid crystals
Two Dimensional Quantitative Measurements of Methyl Radicals in Methane/Air Flame
- received 09/09/2014; accepted 11/19/2014; posted 11/20/2014; Doc. ID 222709
- [full text: PDF (976) KB)]
- Abstract: Two-dimensional (2D) quantitative measurements of methyl (CH3) radicals in a methane/air Hencken flame at atmospheric pressure are performed using coherent microwave Rayleigh scattering (Radar) from Resonance Enhanced Multi-Photon Ionization (REMPI) technique. 2D scanning and subsequent quantification are employed for Radar REMPI. The 2D quantitative results were used to verify the numerical calculations. The Rayleigh-integral effect was involved in the calculation due to the real experimental configuration. A 25% error existed between the experimental results and numerical calculation while the overall concentration distributions between experiment and modeling of single flamelet have fairly good agreement with each other.
- (300.6350) Spectroscopy : Spectroscopy, ionization
- (300.6360) Spectroscopy : Spectroscopy, laser
Temperature dependence of optical narrow-bandpass filter at 1.5 μm
- received 09/10/2014; accepted 11/19/2014; posted 11/20/2014; Doc. ID 222822
- [full text: PDF (1167) KB)]
- Abstract: For superconducting nanowire single-photon detectors, we designed and fabricated an on-chip narrow-bandpass filter at the central wavelength of 1.5 μm to reduce the influence of blackbody radiation from the fiber. The bandpass filter was prepared on a thermally oxidized Si substrate and provided a peak transmittance of 88% at the central passband wavelength and 30 dB suppression at the stop bands. We investigate the temperature dependence of the filter from room temperature to liquid helium temperature. The central wavelength of the passband blueshifted from 1545 ± 2 nm (295 K) to 1526 ± 2 nm (2.9 K). This effect is explained by the different indices of refraction of Si at different temperatures.
- (220.0220) Optical design and fabrication : Optical design and fabrication
- (230.4170) Optical devices : Multilayers
- (310.6860) Thin films : Thin films, optical properties
Strain gauge using Si based optical micro-ring resonator
- received 05/30/2014; accepted 11/19/2014; posted 11/21/2014; Doc. ID 213095
- [full text: PDF (709) KB)]
- Abstract: A strain gauge using the mechanical-optical coupling method is presented in this paper. The Si based optical micro-ring resonator was employed as the sensing element, which was embedded on the micro cantilevers. From the experimental results, by the application of external strain, a clear red shift of the output resonant spectrum of the structure was observed. It has been concluded that the sensitivity of 93.72 pm/MPa has been achieved, which has also been verified using theoretical simulations. This paper provides us a new method for the development of Micro-opto-electro-mechanical Systems (MOEMS) sensors.
- (140.4780) Lasers and laser optics : Optical resonators
- (220.4880) Optical design and fabrication : Optomechanics
- (230.4685) Optical devices : Optical microelectromechanical devices
Fast precalculated triangular mesh algorithm for 3D binary computer generated holograms
- received 10/21/2014; accepted 11/18/2014; posted 11/19/2014; Doc. ID 225332
- [full text: PDF (954) KB)]
- Abstract: A new method for constructing computer generated holograms (CGHs) using precalculated triangular mesh is presented. The speed of calculation can be increased dramatically by exploiting both precalculated base triangle and GPU parallel computing. Unlike algorithms using point-based sources, this method can reconstruct more vivid 3D object instead of ‘hollow image’. In addition, there’s no need to do a fast Fourier transform for each 3D element every time. A ferroelectric liquid crystal spatial light modulator is used to display the binary hologram within our experiment and the hologram of a base right triangle is produced by utilizing just a one step Fourier transform in 2D case, which can be expanded to the 3D case by multiplying by a suitable Fresnel phase plane. All 3D holograms generated in this paper is based on Fresnel propagation, thus the Fresnel plane is treated as a vital element in producing the hologram. A GeForce GTX 770 graphic card with 2GB memory is used to achieve the parallel computing.
- (070.0070) Fourier optics and signal processing : Fourier optics and signal processing
- (090.1760) Holography : Computer holography
- (100.6890) Image processing : Three-dimensional image processing
- (200.0200) Optics in computing : Optics in computing
- (250.0250) Optoelectronics : Optoelectronics
Analysis of multi-mode fiber-bundles for endoscopic spectral-domain optical coherence tomography
- received 11/18/2014; accepted 11/18/2014; posted 11/19/2014; Doc. ID 216363
- [full text: PDF (800) KB)]
- Abstract: A theoretical analysis of the use of a fiber-bundle in spectral-domain optical coherence tomography systems is presented. The fiber-bundle enables a flexible endoscopic design and provides fast, parallelized acquisition of the optical coherence tomography data. However, the multi-mode characteristic of the fibers in the fiber-bundle affects the depth sensitivity of the imaging system. A description of light interference in a multi-mode fiber is presented along with numerical simulations and experimental studies to illustrate the theoretical analysis.
- (060.2350) Fiber optics and optical communications : Fiber optics imaging
- (060.2400) Fiber optics and optical communications : Fiber properties
- (110.4500) Imaging systems : Optical coherence tomography
- (170.4500) Medical optics and biotechnology : Optical coherence tomography
Gluing For Raman Lidar Systems Using the Lamp Mapping Technique
- received 07/22/2014; accepted 11/18/2014; posted 11/19/2014; Doc. ID 217387
- [full text: PDF (698) KB)]
- Abstract: In the context of combined analog and photon counting data acquisition in a Lidar system, glue coefficients are defined as constants used for converting an analog signal into a virtual photon counting signal. Yet in the presence of clouds or high solar background, it is difficult to obtain accurate glue coefficients from Lidar backscattered data. Here we introduce a new method, in which we use the lamp mapping technique, to determine glue coefficients in a manner that does not require atmospheric profiles to be acquired. The lamp mapping technique (LMT) involves scanning a halogen lamp over the aperture of a Lidar receiver telescope such that the optical efficiency of the entire detection system is characterized. The studies shown here involve two Raman Lidar systems; the first from Howard University and the second from NASA/Goddard Space Flight Center. The glue coefficients determined using the LMT versus the glue coefficients determined using the Lidar backscattered method, agreed within 1.2 % for the water vapor channel and within 2.5 % for the nitrogen channel for both Lidar systems. We believe this to be the first instance of the use of laboratory techniques for determining the glue coefficients for Lidar data analysis.
- (010.3640) Atmospheric and oceanic optics : Lidar
- (010.7340) Atmospheric and oceanic optics : Water
- (040.5250) Detectors : Photomultipliers
- (120.0280) Instrumentation, measurement, and metrology : Remote sensing and sensors
- (280.3640) Remote sensing and sensors : Lidar
- (290.5860) Scattering : Scattering, Raman
Diffuse Reflecting Material For Integrating Cavity Spectroscopy - Including Ring-Down Spectroscopy
- received 08/15/2014; accepted 11/17/2014; posted 11/19/2014; Doc. ID 221055
- [full text: PDF (3410) KB)]
- Abstract: We report the development of a new diffuse reflecting material with measured reflectivity values as high as 0.9992 at 532 nm, and 0.9969 at 266 nm. This new material is a high-purity fumed silica, or quartz powder, with particle sizes on the order of 40 nm. We demonstrate that this material can be used to produce surfaces with nearly Lambertian behavior, which in turn can be used to form the inner walls of high-reflectivity integrating cavities. Light reflecting off such a surface penetrates into the material. This means there will be an effective ``wall-time' for each reflection off the walls in an integrating cavity. We measure this wall-time, and show that it can be on the order of several picoseconds. Finally, we introduce a new technique for absorption spectroscopy in an integrating cavity based on cavity ring-down spectroscopy (CRDS). We call this new technique integrating cavity ring-down spectroscopy (ICRDS).
- (160.0160) Materials : Materials
- (160.4670) Materials : Optical materials
- (160.6030) Materials : Silica
- (300.1030) Spectroscopy : Absorption
- (300.6540) Spectroscopy : Spectroscopy, ultraviolet
- (300.6550) Spectroscopy : Spectroscopy, visible
Towards Optical Tweezers Based Force Microscopy for Airborne Microparticles
- received 08/29/2014; accepted 11/17/2014; posted 11/19/2014; Doc. ID 222061
- [full text: PDF (1767) KB)]
- Abstract: Optical tweezers have found widespread application in biological and colloidal physics for the measurement of pN forces over nm to μm length scales. Similar aerosol-phase measurements of inter-particle force have not been reported in spite of the potential to better resolve particle coagulation kinetics. Various refractive index mismatches in the beam path as well as the need to explicitly account for gravity and inertial particle motion provide a number of challenges that must be overcome to make such measurements tractable. In this regard, we demonstrate schemes by which the particle position and trap stiffness may be unambiguously measured using bright-field microscopy with resolution comparable to analogous condensed-phase measurements. Moreover, some of the challenges of working with highly dynamic aqueous particles are introduced and exploited to observe size-dependent phenomena in aerosol optical tweezers. Notably, when combined with cavity enhanced Raman spectroscopy this provides a unique opportunity to explore trapping forces over a continuum of particle size and refractive index. It is expected that the methods developed will provide a basis for the measurement of pairwise interaction forces in aerosol optical tweezers while providing a probe of fundamental airborne particle trapping dynamics.
- (010.1110) Atmospheric and oceanic optics : Aerosols
- (350.4990) Other areas of optics : Particles
- (350.4855) Other areas of optics : Optical tweezers or optical manipulation
- (180.5655) Microscopy : Raman microscopy
Analysis of experimental depolarizing Mueller matrices through a hybrid decomposition
- received 07/16/2014; accepted 11/17/2014; posted 11/19/2014; Doc. ID 217099
- [full text: PDF (434) KB)]
- Abstract: We propose a new decomposition for depolarizing Mueller matrices, consisting of a product of four basic optical devices: two diattenuators, a retarder and a depolarizer. This decomposition, derived from a previous one known as “symmetric decomposition” (R. Ossikowski, J.O.S.A. A, 26, 1109-1118, 2009), makes it easier to interpret the polarization properties of Mueller matrices and improves estimation of the extracted parameters. Its application is illustrated by several theoretical and experimental examples.
- (120.5410) Instrumentation, measurement, and metrology : Polarimetry
- (290.5855) Scattering : Scattering, polarization
- (010.1350) Atmospheric and oceanic optics : Backscattering
- (130.5440) Integrated optics : Polarization-selective devices
On-Orbit Characterization of the VIIRS Solar Diffuser and Solar Diffuser Screen
- received 07/18/2014; accepted 11/17/2014; posted 11/19/2014; Doc. ID 217283
- [full text: PDF (1759) KB)]
- Abstract: We analyze the bidirectional reflectance factors (BRFs) of the solar diffuser (SD) and the vignetting function (VF) of the SD screen (SDS) for the on-board calibration of the Visible Infrared Imaging Radiometer Suite (VIIRS). Specific focus is placed on the products of the BRFs and the VF that are the main inputs for the calibration of the SD and its accompanying solar diffuser stability monitor (SDSM) that tracks SD degradation. The set of 14 spacecraft yaw maneuvers for the Suomi National Polar-orbiting Partnership (SNPP) satellite, which houses the VIIRS instrument, was carefully planned and carried out over many orbits to provide the necessary information on the dependence of VIIRS instrument response on solar angles. Along with the prelaunch measurements for the SDS VF and SD BRFs, the absolute form of the BRF-VF product is determined for each of the reflective solar bands (RSBs) and for each of the SDSM detectors. Consequently, absolute form of the VF is also obtained from both the RSBs and the SDSM detectors using the yaw maneuver data. The results show that the BRF-VF product for an RSB is independent of detector, gain status, and half-angle mirror (HAM) side as expected. The derived VFs from the RSB and SDSM detectors also show good agreement with each other as well as with the prelaunch VF measurements, and further demonstrate only geometrical dependence, which in this work is characterized by solar angles. The derived calibration coefficients, called the F-factors, from the application of the derived functions in this study show a significantly improved pattern. A small band-dependent residual seasonal fluctuation on the level of ~0.2%-0.4% remains in the F-factors for each RSB and is further improved by a corrective function with a linear dependence of solar azimuth angle in the nominal attitude instrument coordinate system to the VF. For satellite ocean color remote sensing, on-orbit instrument calibration and characterization are particularly important for producing accurate and consistent ocean color products. The result of this work has the most significant and direct impact on ocean color products.
- (120.0280) Instrumentation, measurement, and metrology : Remote sensing and sensors
- (120.5630) Instrumentation, measurement, and metrology : Radiometry
- (010.5630) Atmospheric and oceanic optics : Radiometry
- (010.0280) Atmospheric and oceanic optics : Remote sensing and sensors
Hyperspectral quantitative imaging of gas sources in the mid-infrared
- received 06/05/2014; accepted 11/17/2014; posted 11/19/2014; Doc. ID 213489
- [full text: PDF (1804) KB)]
- Abstract: An imaging Fourier-transform spectrometer operating in the medium infrared (1800-5000 cm1) has been used to image two gas sources: a controlled CO2 leak at room temperature and the exhaust of a combustion engine. Spectra have been acquired at a resolution of 0:5 cm1 using an extended blackbody as background. By fitting them with theoretical spectra generated with parameters from the HITRAN database, quantitative maps of temperature and gas column density (concentrationpath product) for the gas plumes have been obtained. Spectra are related to gas plume parameters by means of a radiometric model that takes into account not only gas absorption, but also its emission and the atmospheric absorption, as well as the instrument lineshape function. Measurements for the gas leak show very good agreement between retrieved and nominal values of temperature and CO2 column density. This result has direct application to obtain quantitative imaging of exhaust emissions from automobiles and other mobile sources, as shown here with measurements of exhaust gases in a diesel engine.
- (110.3080) Imaging systems : Infrared imaging
- (280.0280) Remote sensing and sensors : Remote sensing and sensors
- (280.1120) Remote sensing and sensors : Air pollution monitoring
- (280.1740) Remote sensing and sensors : Combustion diagnostics
- (300.6300) Spectroscopy : Spectroscopy, Fourier transforms
- (110.4234) Imaging systems : Multispectral and hyperspectral imaging
Initial conditions for dark soliton generation in normal dispersion fiber lasers
- received 09/03/2014; accepted 11/17/2014; posted 11/20/2014; Doc. ID 222116
- [full text: PDF (541) KB)]
- Abstract: We report results of numerical simulations on the various initial conditions for dark soliton generation in an all-normal-dispersion fiber laser. All the dark solitons generated are odd dark solitons. Different from the dark soliton generation in fibers, where an arbitrary dip could evolve into a dark soliton, it is found that the dark soliton could be originated only from an initial dip with certain parameter requirement. A bright pulse with either hyperbolic secant square, Gaussian, or Lorentz profile can be developed into a dark soliton provided that the parameters of the initial bright pulse are selected. Dark solitons could be generated in fiber lasers only if there exists a phase jump and this phase jump can be maintained and evolved to π during the pulse evolution.
- (190.4370) Nonlinear optics : Nonlinear optics, fibers
- (140.3538) Lasers and laser optics : Lasers, pulsed
- (060.3510) Fiber optics and optical communications : Lasers, fiber
High-frame-rate observation of single femtosecond laser pulse propagation in fused silica using an echelon and optical polarigraphy technique
- received 08/25/2014; accepted 11/17/2014; posted 11/18/2014; Doc. ID 221554
- [full text: PDF (988) KB)]
- Abstract: We have demonstrated high-frame-rate observations of single femtosecond laser pulse propagating in transparent medium using optical polarigraphy technique and an echelon. The echelon produced a spatially encoded time delay for the probe pulse to capture directly four successive images of an intense propagating pulse with picosecond time-interval and femtosecond time-resolution. Using this method, we observed the propagation process of single femtosecond laser pulse in fused silica. The influence of pulseenergy fluctuation on the spatial and temporal distribution of the single laser pulse was visualized using the single-shot measurements.
- (190.3270) Nonlinear optics : Kerr effect
- (190.5530) Nonlinear optics : Pulse propagation and temporal solitons
- (320.2250) Ultrafast optics : Femtosecond phenomena
- (320.7100) Ultrafast optics : Ultrafast measurements
GHz high power Yb-doped picosecond fiber laser and supercontinuum generation
- received 08/29/2014; accepted 11/17/2014; posted 11/18/2014; Doc. ID 221951
- [full text: PDF (588) KB)]
- Abstract: We demonstrated a 97 W all-fiber picosecond master oscillator power amplifier We demonstrated a 97 W all-fiber picosecond master oscillator power amplifier (MOPA) seeding by an actively harmonic modelocked Yb-doped fiber laser. The laser seed pulse duration was 7.7 ps at 1.223 GHz repetition rate with a central wavelength of 1062 nm. In addition, by launching the amplified pulses into a 5 m long photonic crystal fiber (PCF), we obtained a 41.8 W supercontinuum (SC) covering the wavelength from 600 to 1700 nm with a 10 dB bandwidth of 1040 nm.
- (060.2320) Fiber optics and optical communications : Fiber optics amplifiers and oscillators
- (140.3510) Lasers and laser optics : Lasers, fiber
- (320.6629) Ultrafast optics : Supercontinuum generation
High Q and High Sensitive Width Modulated Photonic Crystal Single Nanobeam Air-mode Cavity for Refractive Index Sensing
- received 08/25/2014; accepted 11/16/2014; posted 11/18/2014; Doc. ID 221517
- [full text: PDF (616) KB)]
- Abstract: We propose a novel optical sensor based on a one dimensional (1D) photonic crystal (PhC) single nanobeam airmode cavity (SNAC). The performance of the devices is theoretically investigated. By introducing a quadratically modulated width tapering structure, a waveguide coupled 1D-PhC single nanobeam air-mode cavity with calculated high quality-factor 5.16×106 and an effective mode volume Veff∼2.18 (λ/nsi)3 can be achieved. For the air-mode mentioned above, the light field can be strongly localized inside the air-region (low-index) and overlap sufficiently with analytes. Thus, the suggested PhC single nanobeam air-mode cavity can be used for high sensitivity refractive index sensing with an estimated high sensitivity of 537.8nm/RIU. To the best of our knowledge, this is the first PhC single nanobeam geometry that features both high Q factors and high sensitivity, and is potentially an ideal platform for realizing ultracompact lab-on-a-chip applications with dense arrays of functionalized spots for multiplexed sensing.
- (130.3120) Integrated optics : Integrated optics devices
- (230.5750) Optical devices : Resonators
- (280.4788) Remote sensing and sensors : Optical sensing and sensors
- (230.5298) Optical devices : Photonic crystals