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We demonstrate a high-sensitivity humidity sensor taking advantage of single-band ultranarrow plasmon resonance of a single Au nanorod coupling to a whispering gallery cavity of a polyacrylamide microfiber. (Abstract)

Active modulation of light with large optical bandwidths (∼100 nm [1]) is required in photonic devices, such as modulators for fiber communications [1] and saturable absorbers for ultrafast pulse generation [2,3]. Present modulators use expensive materials, (e.g. LiNbO 3 [4], III-V semiconductors [5], and Ge on silicon-on-insulator (SOI) [6]), and are limited by narrowband operation (∼20 nm for quantum-confined Stark effect devices [7], or 3 N 4 ) while offering a full-band operation [10]. In all-fiber platforms, including ultrafast lasers [2,3], high coupling losses (∼60% from fiber to SOI waveguide [6]) are driving development of fiber-based modulators. Ref. 3 reported an electrically controllable all-fiber optical modulator with a SLG transistor on a side-polished fiber. However, its gating speed was limited to∼300 Hz [11] due to the low mobility of the ionic liquid used for gating. Here, we report a graphene-microfiber modulator by integrating a microfiber onto a graphene (SLG plated) capacitor (GC). By varying the microfiber size and length we control the light interaction with the biased SLG plates. This can be used for active control of ultrafast laser working in continuous wave, Q-switching and mode-locking operations.

We have demonstrated an ultracompact optical correlator for femto-second pulse measurement based on transvers second harmonic generation (TSHG) in a subwavelenth-diameter CdTe nanowire. Benefitted from the high optical nonlinearity and very small effective mode area of the nanowire, pulse energy goes down to less than 3 femtojoules per pulse.

Recently, we had reported some fiber sensing applications by using the tilted fiber Bragg grating (TFBG), such as twist sensor, polarization sensor, curve sensor and relative humidity sensor, and so on. Here, we summarized two kinds of TFBG-based sensors (humidity- and twist-sensing) for the conference of ICOCN 2016. An optical fiber humidity sensors based on a graphene oxide coated on a TFBG and a fiber twist sensor based on the surface plasmon resonance (SPR) effect of an Au-coated TFBG were presented. The sensitivity of 0.129 dB/%RH with a linear correlation coefficient of 99% under the RH range of 10%∼80% was obtained. For the twist ranging from 0 to 180° in clockwise or anti-clockwise directions, the proposed sensor shows sensitivities of 0.037 dBm/°(S-polarized), 0.039 dBm/°(P-polarized), respectively.

Integration of miniaturized elements has been a major driving force behind modern ultrafast photonics. Nanowires have emerged as potential building blocks for compact photonic circuits and devices in nanophotonics. We demonstrate here ultrafast optical modulation and correlation on the single-nanowire scale. Based on saturable absorption in graphene films, we show ultrafast optical modulation in a graphene flakes doped polymer nanofiber and graphene film coated ZnO nanowire. Also, based on imaging the transverse second harmonic generation (TSHG) from a cadmium sulfide (CdS) and a CdTe nanowires, as well as converting the TSHG spatial image into the temporal profile of the pulses, we demonstrate ultrafast optical correlation with pulse energy down to femto-joules.

We demonstrate a hybrid structure microlaser consisting of a single CdSe nanowire attached to a silica microdisk cavity. Lasing threshold of the hybrid structure lower than 12 nJ/pulse is observed.

We demonstrated a pigtailed nanoribbon ring laser constructed with a 400 nm wide and 230 nm thick CdSe nanoribbon. When the 9-μm-diameter ring was irradiated by light from a semiconductor laser (532 nm, 10 ns, 10 Hz) laser, multi longitudinal mode laser emission was observed around 728 nm. The laser output from the pigtail showed strong orientation-dependent polarization, with a maximum polarization ratio of 5.

Dielectric-loaded surface plasmon polariton (DLSPP) is a potential candidate for nanoscale optical elements with sizes much smaller than the diffraction limit and extremely low loss. In this work, we will combine the convenience of fiber based devices and the tight confinement of DLSPP waveguide, and then propose a nanofiber-loaded structure for the DLSPP application. Through the finite element method (FEM) modeling, we demonstrated the hybridization between hybrid surface plasmon polariton modes (HSPPs) and nanofiber modes, and analyzed the generation of hybrid plasmon polaritons (HPPs) super-modes. We also showed the existence of higher order HSPP, which is helpful to reduce the bending loss of DLSPP structure. Due to its polarization dependent transmission loss, we demonstrated one of its applications as polarizer experimentally.

We report a general route to optical sensing with waveguiding polymer single nanowires. Functionalized polymer single nanowires, drawn from solvated polymers, are evanescently coupled to nanoscale fiber tapers for optical launching and signal collection. Based on pronounced changes in waveguiding behavior of the nanowire when exposed to specimens, polymer single-nanowire optical sensors for humidity detection is demonstrated with high sensitivity and fast response.