This document discusses different types of photonic sensors including surface plasmon resonance sensors, whispering gallery mode sensors, and photonic crystal sensors. Surface plasmon resonance sensors detect changes at a metal-dielectric interface and are used for ultrasensitive immunoassays. Whispering gallery mode sensors can detect nanoparticles smaller than 100 nm by measuring changes in resonant frequencies as particles deposit inside an optical cavity. Photonic crystal sensors use a photonic band gap to selectively reflect certain wavelengths of light. Changes in materials deposited on the photonic crystal surface cause shifts in the reflected wavelengths that can be measured.

1. GUIDED BY:
MR. DEEPAK JHANWAR
ASSISTANT PROFESSOR, ECE
GOVT. ENGG COLLEGE, AJMER
PRESENTED BY:
RAM NIWAS BAJYA
(ROLL NO:10EEAEC067)

4. 1. Surface Plasmon Resonance sensor -
Surface Plasmons:
- plasmons confined to surface (interface) and interact with light resulting in polaritons.
- propagating electron density waves occurring at the interface between metal and dielectric.
Surface Plasmon Resonance:
- light ( ) in resonance with surface plasmon oscillation
Plasmons:
- collective oscillations of the “free
electron gas” density, often at optical
frequencies.
Surface plasmon resonance sensors are important for ultrasensitive immunoassays with
applications in health diagnostics.
Fig. 2 SPR sensor and wavelength shift response

5.  Surface Plasmon Resonance sensor working[3]-
Vedio 1 SPR Sensor sense the water drops in nm range[3]

7. 2. whispering gallery mode sensors -
frequency
• They expect the sensor will be able to measure nanoparticles smaller than 100 nanometers in
diameter (about the size of a virus particle) on the fly.
• The light wave can make many trips around the
ring before it is absorbed, but only frequencies
of light that fit perfectly into the circumference
of the ring can do so. If the circumference is a
whole number of wavelengths, the light waves
superimpose perfectly each trip around.
• This perfect match between the frequency and
the circumference is called a resonance. or
whispering-gallery mode. Fig. 3 WGM sensor
• The term whispering-gallery mode (WGM) describes the electromagnetic wave that
circulates around the inner surface of a dielectric sphere or cylinder as the result of total
internal reflection.

8.  whispering gallery mode sensors working -
Vedio 2 Sensing of vires (nm) by WGM Sensor[4]

10. 3. photonic crystal (PhC) sensors -
 WHAT ARE PHOTONIC CRYSTALS?
photon
The quantum of electromagnetic energy, regarded as a
discrete particle having zero mass, no electric charge, and
an indefinitely long lifetime.[2]
crystal
A homogeneous solid formed by repeating, three-
dimentional pattern of atoms, ions, or molecules and having
fixed distances between constituent parts. (from Greek
krustallos)[2]
(a)
(b)
Fig. 3 (a) phc structure
(b) wavelength vs intensity response

11. P. C. = Artificial crystal structure that could manipulate beams of light in the same
way that silicon and other semiconductors control electric current.
Photonic band gap is a range of forbidden frequencies within which a specific
wavelength is blocked, and light is reflected. By designing the spectral and spatial
location of the gap, one can almost mold the flow of light at will.
(Cont…...)

12. • Bragg’s equation: the wavelength of the center of the
stop band can be calculated since the band is a
diffraction based phenomenon
 How do Photonic crystals work?
Fig. 4 phenomena of diffraction in phc
m

13.  PhC Parallel Resonant Cavities [1]-
PhC parallel resonant cavities, which are
composed of two H0-cavties side-coupled
to parallel output waveguides of an optimized
beam-splitter. Here, a = 430 nm, r = 0.32a, r1
= 0.206a, r2 = 0.32a, dx = 0.26a. }
(a) 3D-FDTD transmission spectra for
PhC parallel resonant cavities. sx1 =
0.19a, sx2 = 0.20a, rx = ry = 0.32a. (b)
Steady state electric field profile for the
fundamental TE-like mode propagation
in (b) the xy plane and (c) the yz plane
(the cross section at orange dash line)
with the operating frequency w0 =
0.27(2pic/a).
}Fig. 5 PhC Parallel Resonant Cavities[1]
Fig. 6 spectral and energy response of PhcPRC[1]

14.  Working of one cavity in Phc Sensor-
Fig. 7 Shifting of wavelength[5]

15. (a) 3D-FDTD transmission spectra for Nanoscale PhC integrated sensor array, observed when six sensor units are
integrated on monolithic platform. (b) Electric field distribution for the fundamental TE-like mode propagation in
PhC integrated sensor array[1]
Fig. 8

17.  What can be sensed with photonic crystals?
There is an evanescent wave close to the surface ,which can for sensing of material
close(<100nm) to the surface.
• Environmental Changes
• Temperature
• Ph
• Silicone
• Ultrasound
• Biomedical (Sensitive detection of viruses, chemicals, bacteria, protins etc.)

18. In summary, by using 3D-FDTD, we have theoretically demonstrated a flexible design of
Nanoscale PhC integrated sensor array with high sensitivity and low crosstalk. It is important
to point out that the demodulation of the PhC integrated sensor array is straightforward. When
n sensors are set in cascades, the output transmission of the series exhibits n dips. And the dips
are independent from each other. Thus, the proposed PhC integrated sensor array is desirable
to perform monolithically integrated sensing and multiplexed detection. This allows the
implementation of simple but functional PhC integrated sensor array, and eventually of more
complex sensor networks. In addition, the proposed sensor array makes it possible to enhance
integration density and restrain crosstalk simultaneously.

19. The future for photonic crystal sensors looks certain.
• Increase sensitivity
• Specificity of the assay
• Packaging
• Assay in complex mixture

22. [1 ] Daquan Yang, Huiping Tian, Yuefeng Ji “Nanoscale Low Crosstalk Photonic Crystal Integrated Sensor Array”
Volume 6, Number 1, February 2014
[ 2 ] The American Heritage® Dictionary of the English Language
[ 3 ] http://www.biosensingusa.com/biosensing_instrument_spr_animation.html
[ 4 ] https://www.youtube.com/watch?v=YgEYh5k9yl0
[ 5 ]
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