The use of thermoresponsive poly(N-isopropylacrylamide)-based hydrogel (pNIPAAm) for rapid tuning of surface plasmon resonance (SPR) is reported. This approach is implemented by using an SPR layer architecture with an embedded indium tin oxide microheater and pNIPAAm film on its top. It takes advantage of rapid thermally induced swelling and collapse of pNIPAAm that is accompanied by large refractive index changes and leads to high thermo-optical coefficient of dn/dT = 2 × 10–2 RIU/K. We show that this material is excellently suited for efficient control of refractive index-sensitive SPR and that it can serve simultaneously as a 3D binding matrix in biosensor applications (if modified with biomolecular recognition elements for a specific capture of target analyte). We demonstrate that this approach enables modulating of the output signal in surface plasmon-enhanced fluorescence spectroscopy biosensors and holds potential for simple time-multiplexing of sensing channels for parallelized readout of fluoresc...

Active Control of SPR by Thermoresponsive Hydrogels for Biosensor Applications

We report on photo-thermal modulation of thin film surface plasmon polaritons (SPP) excited at telecom wavelengths and traveling at a gold/air interface. By operating a modulated continuous-wave or a Q-switched nanosecond pump laser, we investigate the photo-thermally induced modulation of SPP propagation mediated by the temperature-dependent ohmic losses in the gold film. We use a fiber-to-fiber characterization set-up to measure accurately the modulation depth of the SPP signal under photo-thermal excitation. On the basis of these measurements, we extract the thermo-plasmonic coefficient of the SPP mode defined as the temperature derivative of the SPP damping constant. Next, we introduce a figure of merit which is relevant to characterize the impact of temperature onto the properties of bounded or weakly leaky SPP modes supported by a given metal at a given wavelength. By combining our measurements with tabulated values of the temperature-dependent imaginary part of gold dielectric function, we compute the thermo-optical coefficients (TOC) of gold at telecom wavelengths. Finally, we investigate a pulsed photo-thermal excitation of the SPP in the nanosecond regime. The experimental SPP depth of modulation obtained in this situation are found to be in fair agreement with the modulation depths computed by using our values of gold TOC.

https://hal.archives-ouvertes.fr/hal-00911957/document

Photo-thermal modulation of surface plasmon polariton propagation at telecommunication wavelengths.

An optical waveguide accelerometer based on tunable asymmetrical Fano resonance in a ring-resonator-coupled Mach–Zehnder interferometer (MZI) is proposed and analyzed. A Fano resonance accelerometer has a relatively large workspace of coupling coefficients with high sensitivity, which has potential application in inertial navigation, missile guidance, and attitude control of satellites. Due to the interference between a high-Q resonance pathway and a coherent background pathway, a steep asymmetric line shape is generated, which greatly improves the sensitivity of this accelerometer. The sensitivity of the accelerometer is about 111.75 mW/g. A 393-fold increase in sensitivity is achieved compared with a conventional MZI accelerometer and is approximately equal to the single ring structure.

High sensitivity optical waveguide accelerometer based on Fano resonance

We demonstrate theoretically a tunable optical ring resonator incorporating an asymmetric Mach-Zehnder interferometer (MZI) and two phase shifters. The optimal resonance state of the ring resonator with different geometries can be achieved by tuning the two embedded phase shifters. Distinct intensity and phase responses and transmission spectra characteristics are newly observed by setting different structural parameters such as the asymmetrical path lengths of the waveguides and the coupling ratio of the directional couplers in the MZI. The performance characteristics related to the radius of the ring cavity and the propagation losses in the waveguides are also discussed. At optimal resonance, it is shown that sharp intensity response and tunable narrow-bandwidth spectra can be achieved especially for resonators with a highly asymmetrical configuration. Such device has a potential in sensing, switching and filtering applications.

Tunable Optical Ring Resonator Integrated With Asymmetric Mach–Zehnder Interferometer

We show theoretically plasmonic antennas based on two-step chemical synthesized silver nano-flags constructed by a silver nanowire and a nanoplate. The silver nano-flag antennas exhibit high polarization sensitivity and diversity of spectral signatures dependent on the structural parameters arising from the observed mode competition. With specific configuration engineering, the antennas show controllable electric-field enhancement and ultra narrow bandwidths down to about 2 nm. These nano-antennas promise exciting applications in lasing spaser, optical modulation, and enhanced nonlinear processes.

Controllable plasmonic antennas with ultra narrow bandwidth based on silver nano-flags

A surface-plasmon-polaritons (SPPs) tunable optical resonant ring filter that includes an SPPs waveguide, an SPPs tunable directional coupler, and an SPPs tunable resonant ring. The tunabilities of the resonant frequency, the resonant depth, and the filtering bandwidth are achieved by tuning the loss and transmission phase of the resonant ring and the coupling ratio of the directional coupler. Since the metal core layer of the SPPs waveguide is capable of multiplexing electro-optical signals, the SPPs tunable optical resonant ring filter can be used not only in an integrated optics system, but also in an integrated electro-optics hybrid system.

Surface-plasmon-polaritons tunable optical resonant ring filter

The invention relates to a regulation and control device of an optical time delay unit, comprising a diode laser (1), an optical fiber (2), an electro-optical switch (3), a photoelectric converter (4) and a regulation and control circuit, wherein the output ends of an optical power control circuit (10) and an automatic temperature control circuit (20) are respectively connected with the input end of the diode laser (1); the output end of a +400 volt supply circuit (40) is respectively connected with the input ends of the electro-optical switch (3) and a high-voltage pulse drive circuit (30), the other input end of the high-voltage pulse drive circuit (30) inputs a transistor-transistor logic (TTL) signal, and the output end of the high-voltage pulse drive circuit (30) is connected with the other input end of the electro-optical switch (3) through a control circuit (50) of the electro-optical switch (3); the output end of the diode laser (1) is connected with the input end of the electro-optical switch (3) through the optical fiber (2), and the output end of the electro-optical switch (3) is connected with the input end of the photoelectric converter (4) through the optical fiber (2).

Regulation and control device of optical time delay unit

A novel polycarbonate (PC) was introduced to apply in the optical waveguide devices. PC has following distinct merits
than common polycarbonate: good processability, high thermal stability up to 293 C°; and high optical transparency.
Optical properties of absorption behavior and propagation loss were investigated in slab waveguides, and low
propagation losses of 0.335 dB/cm (@1550nm) and 0.197 dB/cm @632.8nm) have been achieved by using prismcoupler.
Additionally, straight optical waveguide and MMI coupler of ring resonator were fabricated using ultraviolet
(UV) cured resin Norland optical adhesive 61 (NOA61) as under or upper cladding layer and polycarbonate as
waveguide core-layer material through conventional methods such as spin coating, photolithography and reactive ion
etching (RIE). The process was studied in detail and the experimental results were given.

An experimental study of the fabrication of polycarbonate optical waveguides

An integrated optical waveguide accelerometer relates to a resonant integrated optical waveguide accelerometer with a cantilever beam structure, more precisely, a one-chip integrated highly-sensitive accelerometer The accelerometer comprises an input waveguide, a Mach-Zehnder interferometer with an asymmetric structure, a micro-mechanical vibrating cantilever beam, a bent waveguide, and output waveguide, wherein the input waveguide (1), the Mach-Zehnder interferometer (2) with the asymmetric structure, the micro-mechanical vibrating cantilever beam (3), the short bent waveguide (4), and the output waveguide (5) comprise organic polymer substrates (12), organic polymer waveguide core layers (13) and organic polymer waveguide claddings (14); the micro-mechanical vibrating cantilever beam (3) adopts a dual-beam structure, and is formed by two micro-cantilever beams (16) which are symmetrically distributed in parallel and a mass block (17); one end of each micro-cantilever beam is fixed on a base (11), and the other end thereof is connected with the mass block (17); and the mass block (17) is suspended freely

Integrated optical waveguide accelerometer

A ultrasmall thermal tunable ring resonator based on plasmon-polariton waveguide is theoretically analyzed. The thermooptic coefficient and the temperature-dependent amplitude attenuation coefficient of the effective mode index of the plasmonic waveguide are calculated by finite element method (FEM), and the transmission characteristics of the ring resonator with different structural parameters are investigated. Such device shows high efficient tunability and may be utilized to develop novel tunable plasmonic devices.

Pengqin Wu

Papers

Surface-plasmon-polaritons tunable optical resonant ring filter

Regulation and control device of optical time delay unit

An experimental study of the fabrication of polycarbonate optical waveguides

Integrated optical waveguide accelerometer

Tunable microring resonator based on dielectric-loaded surface plasmon-polariton waveguides