Photonic devices laboratory Sensor-related projects Shlomo Ruschin Environment and Biological Porous Silicon Optical Sensors Sensor based on Periodically Segmented Waveguides Sensors based on active lasing optical waveguides Critical sensitivity effect: SOI sensor Critical sensitivity effect : PSi sensor Collaborators: Prof. Jehudit Rishpon Prof. Menachem Nathan Dr. Asher Peled Tanya Hutter Keren Hakshur

Porous Silicon Optical Sensors Tanya Hutter and Shlomo Ruschin Tel-Aviv University

NH3NH3 NH3NH3 NH 3 NH3NH3 NH3NH3 Ammonia storage warehouse Motivation (1) porous silicon sensors ADVANTAGES: Cheap Small Remote Passive (can be used in flammable environment) Light source and receiving fiber PSi Sensors ALARM !

Motivation (2) porous silicon sensors Breath analysis for clinical applications Ammonia is listed as one of the marker molecules that can identify kidney impairment.

Porous silicon Porous silicon (PSi) is a material formed by electrochemical etching of crystalline silicon. ‘nano-sponge’ 500 nm

Porous silicon (PSi) - Why !?!? Increased surface interaction area m 2 /cm 3. Simplicity and repeatability of fabrication. Ability to produce pores in the range of 30Å to 1μm and porosities of 10-90%. Compatibility with technology: easily integrable with Si- based microelectronics. Biocompatible H. Ouyang et al., Frontiers in Surface Nanophotonics, 2007

Optical Measurement Setup Light from tungsten- halogen lamp passes through collimating lens. The reflected rays are collected and transmitted to a PC via spectrometer. The reflected spectra is collected at wavelengths nm. Experimental optical setup Spectrometer White light source Gas chamber Porous Silicon NH 3 Gas N 2 Gas Humidifier Flowmeters Outlet

Ammonia vapor & pH indicator After Exposure: ammonia reacts with BTB, and the sample changes its color from yellow to blue. Yellow absorbance at nm Blue absorbance at nm The reflected spectrum

Multi-Sensing Principle Porous silicon surface Gas in Gas out

Multi-Sensing Principle Sensor array concept. Each section is made of porous silicon with a different functionality. White light is collimated to illuminate the entire sample. The reflected light from all the sections is measured simultaneously in a non-imaging configuration using a single detector. The obtained spectrum consists of many overlapping interference spectra each reflected from a different sensor section.

PSi sample before and after biotin connection to the PSi sensor. PSi sample before and after Avidin connection to the PSi sensor. Model system: Biotin-Avidin

Periodically Segmented Waveguides and sensors based upon them

The basic PSW-MZI sensor Processing is simpler (single photolithography step)

Examples of sensing systems experimentally tested: DNA Hybridization Toxics- Parathion hydrolase Antigen binding (Biotin-Avidin)

DNA Hybridization

Sensors based on active lasing optical waveguides

Concept Sensor Pump Architecture & detection scheme Suitable for both remote sensing & biomedical device

Nd-doped tapered rib waveguide laser- schematic view, not drawn to scale for clarity Monolithic rare-earth doped sol-gel tapered rib waveguide laser

Emission spectra of the laser device for different input pump powers. Output lasing power as a function of input pump power for different pump wavelengths

Optical gain measurement setup

Critical sensitivity effect in an interferometer sensor Ronen Levy, Shlomo Ruschin*, and Damian Goldring 2mm

The Critical Sensitivity Effect

Critical sensitivity effect in an interferometer sensor Ronen Levy, Shlomo Ruschin*, and Damian Goldring Sensor output power for the scanned wavelength range without illumination (Blue, solid line) and with illumination (Green, dashed line). Splitting effect

Dynamic Range Enhancement and Phase-Ambiguity Elimination in Wavelength-Interrogated Interferometric Sensor Tanya Hutter, 1 Stephen R. Elliott, 1 and Shlomo Ruschin 2,*