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A narrow-band Bragg grating filter based on a long-range surface plasmon polariton (LRSPP) waveguide is theoretically demonstrated. The three-dimensional Au stripe that is embedded in polymer SU-8 acts as both the waveguide and the heating electrode. With the eigen mode expansion and finite element method optimizations, the proposed filter shows a reflectivity of 0.578 and a 3 dB bandwidth of 1.1 nm. The central wavelength can be tuned from 1549.9 nm to 1544.3 nm by varying temperature from 25 °C to 75 °C, while maintaining the optical return loss at −2.5 dB. This proposed tunable filter has potential in on-chip light signal processing. [ABSTRACT FROM AUTHOR]

A thermo-optic waveguide mode switch based on an asymmetric Mach–Zehnder interferometer (MZI) is demonstrated. A metal heater is deposited on one arm of the asymmetric MZI to implement switching between the LP01 and LP11a modes. The polymer/SiO2 hybrid waveguide structure is adopted to decrease the power consumption and switching time. The fabricated device shows a mode extinction ratio of 10.5 dB with a power consumption of 15.4 mW at 1550 nm. The operation bandwidth ranges from 1525 to 1615 nm. The rise time and fall time of mode switching are 71.5 and $140.3~\mu \text{s}$ , respectively. This device has potential in configurable mode-division multiplexing systems. [ABSTRACT FROM AUTHOR]

Formation of laterally continuous ultrathin gold films on polymer substrates is a technological challenge. In this work, the vacuum thermal evaporation method is adopted to form continuous Au films in the thickness range of 7-17 nm on polymers of Poly(methyl-methacrylate-glycidly-methacrylate) and SU-8 film surface without using the adhesion or metallic seeding layers. Absorption spectrum, scanning electron microscope and atomic force microscope images are used to characterize the Au film thickness, roughness and optical loss. The result shows that molecular-scale structure, surface energy and electronegativity have impacts on the Au film morphology on polymers. Wet chemical etching is used to fabricate 7-nm thick Au stripes embedded in polymer claddings. These long-range surface plasmon polariton waveguides demonstrate the favorable morphological configurations and cross-sectional states. Through the end-fire excitation method, propagation losses of 6- wide Au stripes are compared to theoretical values and analyzed from practical film status. The smooth, patternable gold films on polymer provide potential applications to plasmonic waveguides, biosensing, metamaterials and optical antennas. [ABSTRACT FROM AUTHOR]

In this paper, a Mach-Zehnder interferometer (MZI) variable optical attenuator (VOA) based on Norland Optical Adhesive73 (NOA73) material has been designed and fabricated. At 1550 nm wavelength, the insertion loss of the VOA was measured to be about 8.1 dB. The developed VOA exhibited ultra-low power consumption of 1.96 mW and high optical attenuation of -29.3 dB. When the attenuation at 1550 nm wavelength was -24.6 dB, the spectral variation was ±2.5 dB within wavelength range of 1510 nm to 1590 nm. The rise and fall times of the device were 1.7 ms and 1.3 ms, respectively. [ABSTRACT FROM AUTHOR]

Highlights: [•] We optimized and fabricated an organic/inorganic hybrid thermo-optic switch. [•] The device reveals low switching power of 7.2mW and fast response time of 100μs. [•] The driving-noise-tolerance characteristics were investigated. [•] The minimum extinction ratio is larger 18dB under a noise level of 2.5 V pp. [Copyright &y& Elsevier]

A bulk refractive index sensor based on a straight long-range surface plasmon polariton (LRSPP) waveguide is theoretically designed. The waveguide sensor consists of an Au stripe that is embedded in ultraviolet sensitive polymer SU-8. The geometric parameters are optimized by finite difference eigenmode method at the optical wavelength of 850 nm. The sensitivity of 196 dB/RIU/mm can be obtained with a 1.5 μm wide, 25 nm thick Au stripe waveguide. Straight LRSPP waveguides are fabricated by a double layer lift-off process. Its optical transmission is characterized to experimentally prove the feasibility of the proposed design. This sensor has potential for the realization of a portable, low-cost refractometer. [ABSTRACT FROM AUTHOR]

Abstract: Integrated polymeric waveguide biosensors are usually used for the detection of chemical/biological samples. To improve the sensitivity of the conventional waveguide sensors with only one sensing surface, we design and fabricate an improved sensing window with three sensing surfaces based on inductively coupled plasma etching method, whose sensitivity can be enhanced by a factor of 2.8 in theory. The effects of etching parameters, especially the antenna power, the bias power and the O2 flow rate were systematically studied and the parameters were optimized to fabricate the sensing window. A single-mode balanced Mach–Zehnder interferometer waveguide biosensor with the improved sensing window was fabricated under this optimum etching condition, and presented a higher sensitivity than that of the sensor with conventional sensing window. This type of sensing window will be very useful in polymer waveguide biosensor devices. [Copyright &y& Elsevier]

Abstract: A Multimode Interferometers–Mach Zehnder Interference (MMI–MZI) polymer 2×2 thermo-optic switch is proposed using the thermo-optical effect of polymer materials and fabricated by simple direct ultraviolet photolithography process. We utilize a cross-linkable negative photoresist as core material. Once exposed to ultraviolet light through a photomask, the waveguide strips can be obtained upon development. The experiment results show that the switch has a low switching power of less than 7.5mW. [Copyright &y& Elsevier]

Polymer is viewed as an ideal platform for integrated photonics sensing. We propose a polymer waveguide grating coupler with the enhancement of directionality. A gold film mirror beneath the grating coupler is introduced to prevent the power leakage into the substrate. A Bragg grating reflector in series with the coupler is adopted to reverse the forward diffraction light. The finite-difference time-domain method is used to theoretically investigate the dimensional parameters of grating coupler, gold film mirror, as well as the grating reflector. With both two methods, an enhanced coupling efficiency of 51.31 % can be obtained at the wavelength of 1550 nm. The 62-nm wide 1-dB bandwidth covers the C-band. The proposed design has potentials in integrated optical circuit and monolithic integrated sensors. [ABSTRACT FROM AUTHOR]