Huakang Yu, Limin Tong * State Key Laboratory of Modern Optical Instrumentation, Department of Optical Engineering,

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1 Direct coupling of plasmonic and photonic nanowires for hybrid nanophotonic components and circuits Xin Guo, Min Qiu, Jiming Bao, Benjamin J. Wiley, Qing Yang, Xining Zhang, Yaoguang Ma, Huakang Yu, Limin Tong * State Key Laboratory of Modern Optical Instrumentation, Department of Optical Engineering, Zhejiang University, Hangzhou , China. Department of Microelectronics and Applied Physics, Royal Institute of Technology, Electrum 229, Kista, Sweden. Department of Electrical and Computer Engineering, University of Houston, Houston, TX 77204, USA. Department of Chemistry, Duke University, Durham, NC 27708, USA. * To whom correspondence should be addressed. phytong@zju.edu.cn. 1

2 Supporting Information Optical microscope image of a typical fiber taper Figure S1. Optical microscope image of a typical fiber taper drawn from a standard optical fiber (SMF-28, Corning) with 633-nm-wavelength light as input. A nanofiber with diameter of about 300 nm is located at the distal end of the taper. The scale bars are applicable for the horizontal and perpendicular directions, respectively. 2

3 Optical microscope images of assembly processes of hybrid components with ZnO and Ag nanowires Figure S2. Optical microscope images of the assembly process (from a to f) of a hybrid coupler with ZnO and Ag nanowires on a MgF 2 substrate by micromanipulation under an optical microscope. Aqueous Ag nanowire suspensions were first deposited on a MgF 2 substrate and allowed to dry in open air. A single ZnO nanowire was then moved to the MgF 2 substrate by a home made fiber probe (a). A scanning tunneling microscope (STM) probe, synthesized by electrochemical etching method, was mounted on a precisely controlled 3-dimension moving stage to position the nanowires. Due to the van der Waals and electrostatic attractive forces between the nanowires and the substrate, the nanowires can be pushed along the substrate (b-e) and keep the shape after removing the probe (f). Scale bar in a applies to b-f. 3

4 Figure S3. Optical microscope images of the assembly process (from a to f) of a hybrid Mach-Zehnder interferometer (MZI). The MZI was assembled with a 330-nm-diameter ZnO nanowire and a 120-nm-diameter Ag nanowires, with 633-nm-wavelength light launched in (e and f) and picked up (f) by nanofibers. Scale bar in a is applicable for b, and Scale bar in c is applicable for d-f. Estimation of fractional outputs in Fig. 2c-e and coupling efficiency in Fig. 2e To measure the outputs in Figs. 2c to 2e, we first imaged the nanowire output using a calibrated CCD camera (DS- 5Mc, Nikon) without saturation in dark-field mode of the optical microscope (80i, Nikon), selected a 50 x 50 pixel area (centered around the output spot) and transformed the brightness into grey level information using Adobe Photoshop (the similar approach employed in a recent work 1 ), and then obtained the relative intensity of the output by summing up the grey values. The fractional output from the Ag nanowire was obtained as the ratio of output intensity of the Ag nanowire to the total output of the both nanowires. To estimate the coupling efficiency in Fig. 2e, we considered the fractional output and the guiding losses induced by Ag and ZnO nanowires. The guiding loss of the 7.2-µm-length Ag nanowire is about 3 db (about 0.43 db/µm 1,2 ) and that of the ZnO nanowire is negligible (lower than 0.001dB/µm). Therefore, the coupling efficiency was calibrated by 4

5 deducing the guiding loss from the fractional output (about 64% at 650-nm-wavelength), that is, about 82% at 650-nmwavelength. References 1. Pyayt, A. L.; Wiley, B.; Xia, Y. N.; Chen, A. T.; Dalton, L. Nat. Nanotechnol. 2008, 3, Ditlbacher, H.; Hohenau, A.; Wagner, D.; Kreibig, U.; Rogers, M.; Hofer, F.; Aussenegg, F. R.; Krenn, J. R. Phys. Rev. Lett. 2005, 95,