Fano filter modal analysis based on transferred silicon nanomembranes on flexible substrates Zexuan Qiang 1,2 , Li Chen 1 , Hongjun Yang 1 , Huiqing Pang 3 , Zheqiang Ma 3 , and Weidong Zhou 1* 1 Department of Electrical Engineering, NanoFAB Center, University of Texas at Arlington, TX 76019, USA 2 School of Physics and Optoelectronics Technology, Fujian Normal University, Fuzhou, 35007, P. R. China 3 Department of Electrical and Computer Engineering, University of Wisconsin-Madison, WI 53706, USA ABSTRACT We here proposed a new kind of ultra-compact filters based on Fano resonances on patterned single crystalline silicon nanomembranes (SiNM), which were fabricated and transferred onto transparent substrates like PET plastic and glass substrates, using a wet transfer process. The angular and polarization dependent transmission characteristics of the filter are experimentally investigated. The filter transmission characteristics are insensitive to the incident angle and polarization for surface-normal incidence. For other incident angle conditions, the transmission peaks/dips shift, according to the modal dispersion properties, as verified with the simulated modal dispersion curves. Both surface- normal and angle-dependent filter transmission measurement results agree well with the numerical simulations. Keywords: Photonic crystals, Filters, Fano resonance, Nanomembranes, Angle dependence 1. INTRODUCTION Ultra-compact and sensitive filters are of great importance in optical fiber communication, optical sensor, and millimeter-wave communication systems. Traditional thin-film based filters operating at infrared regime especially for dense wavelength division multiplexing (DWDM) applications, usually require hundreds or more individual layers, with stringent thickness tolerances for each layer and are thus very difficult to satisfy the mission of nanophotonics. Photonic crystal slabs (PCS) are one of the most promising artificial platforms with in-plane periodic modulation of dielectric constant on a wavelength scale. The out-of-the-plane optical mode coupling is feasible with the Fano or guided resonance effect [1, 2], where these in-plane guided resonances above the lightline are also strongly coupled to out-of- the-plane radiation modes due to phase matching provided by the periodic lattice structure. Therefore, the guided resonances can provide an efficient way to channel light from within the slab to the external environment, and vise versa [3]. In recent years, devices based on Fano resonance like narrowband filters [1, 4, 5] or broadband reflectors [6, 7] have been proposed. However, works report to date are mainly based on freestanding membrane, which has some limitations in mechanical robustness and thermal management challenges. In addition, the modal behavior of such configurations with substrate affected by the polarization and angle of incident light hasn’t been investigated yet, which will provide us a more realistic structure. Recently, crystalline semiconductor nanomembranes (NMs) have attracted great attention since they are transferable, stackable, bondable and manufacturable, offering unprecedented opportunities for unique and novel electronic and photonic devices for vertically stacked high density photonic/electronic integration. High quality single crystalline silicon NMs (SiNM) have been transferred onto various foreign substrates, such as glass, plastics, etc., based on low temperature transfer processes, developed by various groups [8-10]. Very high performance electronics based on transferable Si/SiGe NMs were also reported recently [11]. * wzhou@uta.edu . Active Photonic Crystals II, edited by Sharon M. Weiss, Ganapathi S. Subramania, Florencio García-Santamaría Proc. of SPIE Vol. 7031, 703109, (2008) · 0277-786X/08/$18 · doi: 10.1117/12.794072 Proc. of SPIE Vol. 7031 703109-1