Poly-3-hexylthiophene (P3HT) nanofibers are semiconducting high-aspect ratio nanostructures with anisotropic absorption and birefringence properties found at different regions of the optical spectrum. In addition, P3HT nanofibers possess an ability to be aligned by an external electric field, while being dispersed in a liquid. In this manuscript we show that such collective ordering of nanofibers, similar to liquid crystal material, significantly changes the properties of transmitted light. With a specially fabricated opto-fluidic component, we monitored the phase and transmission modulation of light propagating through the solution of P3HT nanofibers, being placed in the electric field with strength up to 0.1 V/μm. This report describes a technique for light modulation, which can be implemented in optical fiber-based devices or on-chip integrated components.

This Letter reports the electro-optical (EO) effect of Poly(3-hexylthiophene-2,5-diyl) (P3HT) nanofibers colloid in a polymer micro-fluidic EO cell. P3HT nanofibers are high aspect ratio semiconducting nanostructures, and can be collectively aligned by an external alternating electric field. Optical transmission modulated by the electric field is a manifestation of the electro-optical effect due to high inner crystallinity of P3HT nanofibers. According to our results, the degree of alignment reaches a maximum at 0.6 V/μm of electric field strength, implying a big polarizability value due to geometry and electrical properties of P3HT nanofibers. We believe that one-dimensional crystalline organic nanostructures have a large potential in EO devices due to their significant anisotropy, wide variety of properties, low actuation voltages, and opportunity to be tailored via adjustment of the fabrication process.

A graphene-based silicon hybrid plasmonic waveguide modulator with 25GHz 3dB bandwidth is proposed in this work. Due to high optical power density at the graphene layers, modulation depth can reach as high value as 0.95dB/μm.

A Mach–Zehnder interferometer (MZI)-based liquid refractiveindex sensor, utilizing a hollow hybrid plasmonic (HP)waveguide as the sensing element, has been investigated,showing large sensitivity to the refractive index changesof the tested liquids, as well as lower propagation loss incomparison to typical plasmonic waveguide-based ones.The sensor is fabricated using conventional silicon-oninsulator(SOI) technology; therefore, it is compatible toother standard SOI devices. The waveguide sensitivity, Sw,is experimentally demonstrated to be 0.64, with a propagationloss less than 0.25 dB/μm. Using a 20 μm long hollowHP waveguide in the sensing arm, the sensitivity of the MZIsensor (device sensitivity, Sd ) is about 160 nm/RIU, with anextinction ratio larger than 40 dB.

The decades long development in shrinking footprint and improving performance of photonics integrated circuits has seemingly slowed down in recent years, posing problems in e g interconnects in data centers with their ever increasing power requirements. Thus, routes to a continued development towards smaller footprint, lower power, higher performance integrated nanophotonics will be presented and discussed. Comparison to some nanoelectronics devices will be made.

A MEMS tunable hybrid plasmonic-Si (HP) waveguide is investigated, showing verylarge changes of both effective refractive index and propagation loss when applying bias voltage.Preliminary experimental results show that: with 15μm MEMS structure in Si waveguideplatform, the extinction ratio can be over 20dB between “on” and “off” states.

This paper gives a review of the recent progresses in our research on nanophotonics and hybrid plasmonic geometries, structures and devices. In the first part we present SOI-nanowire-based integrated components. The concept and different configurations of hybrid plasmonic structures will be then discussed. Finally different fabricated devices for applications in optical interconnects and sensing will be presented and characterized.

We propose and demonstrate an ultracompact on-chip photothermal power monitor based on a silicon hybrid plasmonic waveguide (HPWG), which consists of a metal strip, a silicon core, and a silicon oxide (SiO2) insulator layer between them. When light injected to an HPWG is absorbed by the metal strip, the temperature increases and the resistance of the metal strip changes accordingly due to the photothermal and thermal resistance effects of the metal. Therefore, the optical power variation can be monitored by measuring the resistance of the metal strip on the HPWG. To obtain the electrical signal for the resistance measurement conveniently, a Wheatstone bridge circuit is monolithically integrated with the HPWG on the same chip. As the HPWG has nanoscale light confinement, the present power monitor is as short as ~3 μm, which is the smallest photothermal power monitor reported until now. The compactness helps to improve the thermal efficiency and the response speed. For the present power monitor fabricated with simple fabrication processes, the measured responsivity is as high as about 17.7 mV/mW at a bias voltage of 2 V and the power dynamic range is as large as 35 dB.

A novel hybrid plasmonic (HP) donut resonator integrated with a photothermal plasmonic absorber has been developed, which can be used as a compact all-optical switch or modulator. The radius of the fabricated HP donut resonator is 1.8 mu m, with a resonant wavelength around 1550 nm and a quality factor (Q factor) around 600. The photothermal plasmonic absorber is directly integrated above the HP device, which can absorb as much as 75% of impinging optical power at 1064 nm wavelength. Since the absorber is in tight contact to the Si ridge of the HP waveguide, the absorbed optical power can efficiently heat up the Si ridge, and hence change the resonant wavelength of the HP donut resonator by Si thermal expansion effect. Experimental results show that the power used for 15 dB amplitude switch is only 10 mW, with rise and fall response times around 18 and 14 mu s, respectively.

Poly-3-hexylthiophene (P3HT) nanofibers are 1D crystalline semiconducting nanostructures, which are known for their application in photovoltaics. Due to the internal arrangement, P3HT nanofibers possess optical anisotropy, which can be enhanced on a macroscale if nanofibers are aligned. Alternating electric field, applied to a solution with dispersed nanofibers, causes their alignment and serves as a method to produce solid layers with ordered nanofibers. The transmission ellipsometry measurements demonstrate the dichroic absorption and birefringence of ordered nanofibers in a wide spectral range of 400–1700 nm. Moreover, the length of nanofibers has a crucial impact on their degree of alignment. Using electric birefringence technique, it is shown that external electric field applied to the solution with P3HT nanofibers can cause direct birefringence modulation. Dynamic alignment of dispersed nanofibers changes the refractive index of the solution and, therefore, the polarization of transmitted light. A reversible reorientation of nanofibers is organized by using a quadrupole configuration of poling electrodes. With further development, the described method can be used in the area of active optical fiber components, lab-on-chip or sensors. It also reveals the potential of 1D conducting polymeric structures as objects whose highly anisotropic properties can be implemented in electro-optical applications.​