Angle-Sensitive Detector Based on Silicon-On-Insulator Photodiode Stacked with Surface Plasmon Antenna

Abstract

We present a pixel-level angle sensitive detector composed of silicon-on-insulator (SOI) photodiode (PD) stacked with a gold surface plasmon (SP) antenna to affect the direction of the incoming light. The surface plasmons are excited in the grating-type SP antenna and enhance the diffraction efficiency of the grating. The diffracted light is coupled strongly with the propagation light in the SOI waveguide when the phase matching condition is satisfied. The phase matching takes place at a specific angle of light incidence, and the discrimination of the light based on the incident angle is achieved. As spatial patterns in the polar coordinate of the elevation-azimuth angles (θ, ϕ) of the incident light, we present the phase matching condition theoretically, the absorption efficiency in the SOI by simulation, and also the quantum efficiency of the SOI PD experimentally for different SP antennas of one-dimensional (1D) line-and-space (L/S) and two-dimensional (2D) hole array gratings under various polarization angles. 1D grating offers a polarization sensitive angle detection and 2D grating exhibits angle detection in two orthogonal directions, enabling a polarization independent angle sensitivity. A good agreement among the theory, simulation, and experiment are attained. The proposed device features relatively high quantum efficiency as an angle-sensitive pixel (ASP) and gives wider opportunities in applications such as three-dimensional (3D) imaging, depth-of-field extension, and lensless imaging.

Refractive Index Measurement Using SOI Photodiode with SP Antenna toward SOI CMOS-Compatible Integrated Optical Biosensor

“…These originate from the coupling efficiency between the diffracted light from Au L/S-type SP antenna and the laterally guided wave (in x -direction) based on the eigenmode in the slab waveguide consisting of the SOI sandwiched by silicon dioxide (SiO 2 ). When the phase-matching condition between the wavelengths in x -direction of these lights is satisfied, the light-absorption efficiency in SOI can be enhanced, resulting in higher QEs with a sharp peak in wavelength and incident angle [ 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. Since the wavelength in x -direction of the diffracted light is modulated by the RI of the medium around the SP antenna, it becomes possible for our proposed PD to sense an imperceptible change in the RI corresponding to biomolecular interactions.…”

“…The principle for RI measurement using the SOI PD with an SP antenna is based on the phase-matching condition between the diffracted light from the L/S grating-type SP antenna and the guided mode in the SOI PD body. When the phase-matching condition is satisfied, the peak appears in spectroscopic photocurrent [ 11 , 12 , 13 , 14 ]. Considering the additional condition for the RI on the incident side, the modified phase-matching condition can be obtained, as shown in Figure 4 .…”

“…The first is that a sharp peak can be observed in the spectroscopic light sensitivity when the phase-matching condition is satisfied between two lateral wavelengths of the diffracted light from the SP antenna and the waveguiding mode in SOI PD. Additionally, we have investigated the dependence of spectroscopic light sensitivity on incident angle to the PD surface [ 11 , 12 , 13 , 14 ] and demonstrated that the observed peak wavelengths were modulated by the phase difference in incident plane wave between two adjacent lines of SP antenna. Since the phase difference depends on the RI of the incident-side medium, the peak wavelengths are further modulated.…”

Demonstration of SWIR Silicon-Based Photodetection by Using Thin ITO/Au/Au Nanoparticles/n-Si Structure

“…Once these plasmon-induced hot carriers are transferred across the Schottky barrier (SB) at the metal-semiconductor interface, they will be collected as photocurrents to realize optical detection [23]. The outstanding light-trapping and electromagnetic-field-concentrating properties enable significant absorption enhancement, which is the basis for the effective improvement of PD responsivity [18,[24][25][26]. For instance, the photocurrent detected at the Au/Si interface of the Si SP waveguide detector is much higher compared with that detected from the device without the diffraction structure (26 times for the multi-slit structure and 10 times for the disk array) [27].…”