1. 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

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

3. 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 !

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

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

6. Porous silicon (PSi) - Why !?!? Increased surface interaction area 200-1000 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

7. 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 400- 1000nm. Experimental optical setup Spectrometer White light source Gas chamber Porous Silicon NH 3 Gas N 2 Gas Humidifier Flowmeters Outlet

8. Ammonia vapor & pH indicator After Exposure: ammonia reacts with BTB, and the sample changes its color from yellow to blue. Yellow absorbance at 400-430nm Blue absorbance at 550-650nm The reflected spectrum

9. Multi-Sensing Principle Porous silicon surface Gas in Gas out

10. 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.

11. 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

12. Periodically Segmented Waveguides and sensors based upon them

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

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

15. DNA Hybridization

16. Sensors based on active lasing optical waveguides

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

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

19. 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

20. Optical gain measurement setup

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

22. The Critical Sensitivity Effect

23. 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

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