Surface plasmon resonance transmission filters at 1053 nm based on metallic grating with narrow slit

Metallic gratings with narrow slits can lead to special optical properties such as strongly enhancing the transmission and considerably strengthening the polarized effect. A narrow-band filter suitable for application in optical communication is designed by sandwiching a metallic grating between two identical dielectric films. The maximum transmission can reach 96% after optimizing the parameters of films and grating at a central wavelength of 1053 nm. It is the first time, to our knowledge, that such high transmission has been reported since the discovery of the extraordinarily high transmission through periodic holes or slits; moreover, the extremely polarized effect is also found in P mode of this symmetric grating.

System model for studying fibre grating dispersion compensators

A complete optical system model has been developed and used to assess chirped fibre Bragg grating dispersion compensators. Gratings suitable for dispersion compensation in both laser based and modulator based optical communications systems have been modelled. A grating 10 cm in length has been shown to permit virtually dispersion free transmission over 425 km, when used in an externally modulated system. Long haul dispersion compensation using several 2 cm gratings spaced at intervals along the fibre is also modelled, illustrating viable 10Gbit/s transmission over a distance in excess of 168 km.

Fibre optic distributed sensor system for condition monitoring of synthetic ropes

Reliability of the measuring devices is very important problem. Optical fibre sensors are very efficient. The use of optical fibre sensors for monitoring the physical and chemical parameters has been expanding over resent years. These sensors are applied for monitoring the structural integrity of long, parallel lay synthetic ropes. Such ropes are corrosion free, however, their operational lifetime under cyclic load is not well understood and premature failure can occur due to slippage and breakage of yarns within the rope. The monitoring system has been proposed which is based on acoustic detection of yarn breakage. Monitoring the strain and temperature is performed using the array of fibre gratings distributed along the rope length.

Performance of single mode laser components using 2D photonic lattice reflectors

This paper will report studies of the placement of 2D photonic gratings on either side of the ridge in a Fabry Perot laser device in order to cause single mode emission. Using this approach, side mode suppression ratios of up to 30 dB are achieved, the emission remaining single mode even under 10 Gb/s large signal modulation. It is found that the use of the grating not only causes spectrally dependent reflection but in addition can lead to transverse mode fluctuations. The action of the grating has been studied not just in terms of its edge emission where conversion of the transverse modes is achieved, but also through measurement of the vertical emission from the structure where strong filtering action is observed.

Dynamics in dye-doped LC systems in presence of trans-cis isomerism

The excitation as well as relaxation dynamics of dye-doped nematic liquid crystal cells has been explored both experimentally and theoretically. Overshoots in the build up of the probe signal diffracted from gratings written onto dye-doped liquid crystal systems have often been observed. The overshoot behaviour makes the accurate measurement of nonlinear optical (NLO) response magnitude difficult and ambiguous. Moreover, it complicates the understanding of the dynamics and the physics of the NLO processes. On the basis of the system with trans-cis isomerisation as a mechanism of the NLO effect the quantitative model has been built to describe the experimental results which we observe. The two unknown material parameters: diffusion coefficient and cis species lifetime are calculated from the relaxation data. A quantitative model of the signal build-up uses these parameters. The calculated dynamic behaviour based on this model correlates very well with the experimental data. The model is used to predict the performance of the system with various dopant diffusion properties.

Free space adaptive optical interconnect, using a ferroelectric liquid crystal SLM for beam steering

A free-space, board-to-board, adaptive optical interconnect demonstrator has been developed. Binary phase gratings displayed on a Ferroelectric Liquid Crystal Spatial Light Modulator are used to maintain data transfer at 1.25Gbps, given varying optical misalignment © 2005 Optical Society of America.

Diffraction based phase compensation method for phase-only liquid crystal on silicon devices in operation.

A method to measure the optical response across the surface of a phase-only liquid crystal on silicon device using binary phase gratings is described together with a procedure to compensate its spatial optical phase variation. As a result, the residual power between zero and the minima of the first diffraction order for a binary grating can be reduced by more than 10 dB, from -15.98 dB to -26.29 dB. This phase compensation method is also shown to be useful in nonbinary cases. A reduction in the worst crosstalk by 5.32 dB can be achieved when quantized blazed gratings are used.

Free space communications with beam steering a two-electrode tapered laser diode using liquid-crystal slm

A free space optical wireless communication system with 3 degree angular coverage and 1.25 GHz modulation bandwidth is reported, in which relatively narrow laser beam of a simultaneous high power, high modulation speed and ultra high modulation efficiency directly modulated two-electrode tapered laser diode is steered using a nematic phase-only Liquid-Crystal On Silicon Spatial Light Modulator (LCOS SLM) by displaying reconfigurable 256 phase level gratings. © 1983-2012 IEEE.

Visible diffraction from graphene and its application in holograms

A fundamental study of visible diffraction effects from patterned graphene layers is presented. By patterning graphene into optical gratings, visible diffraction from graphene is experimentally measured as a function of the number of layers and visible wavelengths. A practical application of these effects is also presented, by demonstrating an optical hologram based on graphene. A high resolution (pixel size 400 nm) intensity hologram is fabricated which, in response to incident laser light, generates a visible image. These findings suggest that visible diffraction in graphene can find practical application in holograms and should also be considered during the design and characterisation of graphene-based optical applications. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Free space adaptive optical interconnect, using a ferroelectric liquid crystal SLM for beam steering

A free-space, board-to-board, adaptive optical interconnect demonstrator has been developed. Binary phase gratings displayed on a Ferroelectric Liquid Crystal Spatial Light Modulator are used to maintain data transfer at 1.25Gbps, given varying optical misalignment.© 2005 Optical Society of America.

Reusable, robust, and accurate laser-generated photonic nanosensor.

Developing noninvasive and accurate diagnostics that are easily manufactured, robust, and reusable will provide monitoring of high-risk individuals in any clinical or point-of-care environment. We have developed a clinically relevant optical glucose nanosensor that can be reused at least 400 times without a compromise in accuracy. The use of a single 6 ns laser (λ = 532 nm, 200 mJ) pulse rapidly produced off-axis Bragg diffraction gratings consisting of ordered silver nanoparticles embedded within a phenylboronic acid-functionalized hydrogel. This sensor exhibited reversible large wavelength shifts and diffracted the spectrum of narrow-band light over the wavelength range λpeak ≈ 510-1100 nm. The experimental sensitivity of the sensor permits diagnosis of glucosuria in the urine samples of diabetic patients with an improved performance compared to commercial high-throughput urinalysis devices. The sensor response was achieved within 5 min, reset to baseline in ∼10 s. It is anticipated that this sensing platform will have implications for the development of reusable, equipment-free colorimetric point-of-care diagnostic devices for diabetes screening.

A highly efficient light-trapping structure for thin-film silicon solar cells

A highly efficient light-trapping structure, consisting of a diffractive grating, a distributed Bragg reflector (DBR) and a metal reflector was proposed. As an example, the proposed light-trapping structure with an indium tin oxide (ITO) diffraction grating, an a-Si:H/ITO DBR and an Ag reflector was optimized by the simulation via rigorous coupled-wave analysis (RCWA) for a 2.0-mu m-thick c-Si solar cell with an optimized ITO front antireflection (AR) layer under the air mass 1.5 (AM1.5) solar illumination. The weighted absorptance under the AM1.5 solar spectrum (A(AM1.5)) of the solar cell can reach to 69%, if the DBR is composed of 4 pairs of a-Si:H/ITOs. If the number of a-Si:H/ITO pairs is up to 8, a larger A(AM1.5) of 72% can be obtained. In contrast, if the Ag reflector is not adopted, the combination of the optimized ITO diffraction grating and the 8-pair a-Si:H/ITO DBR can only result in an A(AM1.5) of 68%. As the reference, A(AM1.5) = 31% for the solar cell only with the optimized ITO front AR layer. So, the proposed structure can make the sunlight highly trapped in the solar cell. The adoption of the metal reflector is helpful to obtain highly efficient light-trapping effect with less number of DBR pairs, which makes that such light-trapping structure can be fabricated easily.

Fabrication of triplexers based on flattop SOI AWG

A triplexer is fabricated based on SOI arrayed waveguide gratings (AWGs). Three wavelengths of the triplexer operate at different diffraction orders of an arrayed waveguide grating. The signals of 1490 nm and 1550 nm, which are input from central input waveguide of an AWG, are demultiplexed and the signal of 1310 nm, which is input from central output waveguide of an AWG, is uploaded. The tested results show that the downloaded and uploaded signals have flat-top response. The insertion loss is 9 dB on chip, the nonadjacent crosstalk is less than -30 dB for 1490 nm and 1301 nm, and is less than -25 dB for 1550 nm, the 3 dB bandwidth equates that of the input light source.

DISCRETELY TUNABLE FIBER RING LASER USING FBG TUNABLE FILTER AND MACH-ZEHNDER INTERFEROMETER

A discretely tunable Er-doped fiber-ring laser using a fiber Mach-Zehnder interferometer (MZI) and a tunable fiber Bragg grating (FBG) is proposed. In this scheme, the combination of MZI and FBG acts as a discrete wavelength selector. Analysis of its transmission function shows that discrete wavelength tuning can be realized, and experiments demonstrate 64 single-mode outputs with a mode spacing of 181.7 pm, and the output power is quite stable in the whole tuning range. (C) 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51 2595-2598, 2009; Published online in Wiley InterScience (www. interscience.wiley.com). DOI 10.1002/mop.24690

Experimental demonstration of distributed feedback semiconductor lasers based on reconstruction-equivalent-chirp technology

In this paper we report, to the best of our knowledge, the first experimental realization of distributed feedback (DFB) semiconductor lasers based on reconstruction-equivalent-chirp (REC) technology. Lasers with different lasing wavelengths are achieved simultaneously on one chip, which shows a potential for the REC technology in combination with the photonic integrated circuits (PIC) technology to be a possible method for monolithic integration, in that its fabrication is as powerful as electron beam technology and the cost and time-consuming are almost the same as standard holographic technology. (C) 2009 Optical Society of America