Cell counting optical planar waveguide sensor based on (Yb,Nb):RTP/RTP(001) system

Presented byDr. Muhammad Ali Butt

Co-Authors

E.S. Kozlova, S.N. Khonina, R.V. Skidanov

Samara State Aerospace University, Russia

ITNT CONFERENCE, 17-19 May 2016Samara, Russia

2

Waveguides have been in wide spread use in the telecommunications industry for over 25 years, and have been employed in recent years as a biosensor for detection and diagnostics. The evanescent field has been exploited in many ways as a sensing mechanism.

SEM image of a single human lymphocyte

Aim of this work

This technology enables the enumeration of cells from blood, urine or other biofluids.

Evanescent wave interacting with the metal tagged objects placed on top of the buried planar waveguide

Waveguide core

Evanescent field of the waveguideMetal-tagged objects

to be counted

Substrate

3

Waveguides are the structures that confines the optical radiation by total internal reflection

Step -index waveguide

Techniques of fabrication

Step-index

Liquid phase epitaxy

Molecular beam epitaxyPulsed laser deposition

Sputtering

Laser writing(refractive index modification)

a) Radiation mode

b ) Substrate mode

c) Guided mode

Waveguides

Light behaviour in optical waveguide

Refractive index profile of a waveguide

4

LiNbO3

KNbO3

LiB3O5

β-BaB2O4

AgGaS2

BiB3O6

ZnGeP2

KTiOPO4 (KTP)

RbTiOPO4 (RTP)

Non-linear optical crystals

As grown RTP crystal by TSSG method

As grown epitaxial layer on 001 oriented substrate

Cutting and polishing of crystal

5

RTP as a powerful candidate for integrated photonics

SHG applications

Laser damage threshold is around 2 times larger than KTP

Electro-optic applications

Active material (Yb3+)

OPO applications

Candidate to SFD material for compact and efficient laser sources

RTPHigh electro-optical coefficientsHigh non-linear coefficients

6

Solution compositions for single crystal growth

nx ny nz

RTP 1.7893 1.8015 1.8897

(Yb,Nb):RTP 1.7863 1.8016 1.8967

∆n -0.003 0.0001 0.007

Table 1. Refractive indices at 633 nm

SubstrateRbTiOPO4

Rb2O- TiO2- P2O5- WO3 44.24- 16.8- 18.96- 20 (mol %)

Epitaxial layer (Yb,Nb):RbTiOPO4

Rb2O-P2O5-TiO2-Nb2O5-Yb2O3-WO3

43.9 - 23.6 - 20.7 - 0.45 - 1.35 - 10 (mol %)

7

1)

2)

3)

Previous work on RTP crystal

8

• Beam Prop software

• Propagation length= 9 mm

• Waveguide width= 100 µm

• Confinement along Z crystallographic

direction

• Propagation of light along X

crystallographic direction

• Metal coated cells are placed at 3 mm

till 7 mm on the waveguide.

Waveguide design

X

Y

Z

Y

Z

X

Model of Waveguide without cells

Model of Waveguide with cells

9

Evanescent wave interacting with metal tagged objects placed on planar waveguide

Propagation of light in a waveguide (a) without cells, (b) with cells for waveguide

BeamProp software:Alternating Direction Implicit (ADI) scheme for simulation 633 nm at TM

polarization

Y (µm) Y (µm)

X (µ

m)

X (µ

m)

10

Proposed steps of fabrication of waveguide sensor based on (Yb,Nb):RTP/RTP(001)

system

11

Optimization of core height with respect to cell concentration

Power vs distance for waveguide with the core thickness of 2 (line 1),3 (line 2) and 4 (line 3) microns for 5 % cells (a) and 15 % cells (b).

0 3 6 90

0 .2

0 .4

0 .6

0 .8

1

D istan e , m mс

Pow

er, a

.u.

123

0 3 6 90

0 .2

0 .4

0 .6

0 .8

1

D istan e , m mс

Pow

er, a

.u.

123

Cell concentration=5% Cell concentration=15%

12

Power versus Conc. of different metal coated cells for waveguide

Fill %\core thickness 2 3 41 0,6053 0,7525 0,92923 0,1395 0,5174 0,64155 0,1209 0,3481 0,66517 0,072 0,2277 0,473310 0,0923 0,2149 0,306815 0,019 0,1185 0,3229

Table 2. The normed output power of planar waveguide with aluminium coated cells

Concentration, %

0.01 0.03 0.05 0.07 0.1 0.15

Number 250 750 1250 1750 2500 3750

TABLE 3. THE RATIO OF CONCENTRATION AND THE NUMBER OF

CELLS

Out

put P

ower

F ill % of faux cells

Al C ore height 2 m icrons

C ore height 3 m icrons

C ore height 4 m icrons

03 6 9 12 150

0.2

0.4

0.6

0.8

1

Out

put P

ower

F ill % o f faux cells

Ag C ore height 2 m icrons

C ore height 3 m icrons

C ore height 4 m icrons

03 6 9 12 150

0.2

0.4

0.6

0.8

1

13

1) Power decay in waveguide with periodic and random cell distribution

Power vs distance for waveguide with core height 3 µm for 1% cells concentrations in case of uniform (line 1) and random (line 2)

№line

Cell distribution

Cell sizes (µm) Stotal, µm2

Vtotal, µm34x4x4 10x10x4 15x15x4 10x10x10 15x15x15

1 Uniform 250 - - - - 4000 16000

2 Random 250 - - - - 4000 16000

0 3 6 90

0 .2

0 .4

0 .6

0 .8

1

D istan e , m mс

Pow

er, a

.u.

12

14

2) Power decay in waveguide with different size of random cells distribution

Power vs distance for waveguide with core height 3 µm for 1% cells concentrations in case of random distribution of cells with the same size (line 1) and with different size (line 2-3)

№line

Cell distribution

Cell sizes (µm) Stotal, µm2

Vtotal, µm34x4x4 10x10x4 15x15x4 10x10x10 15x15x15

1 Random 250 - - - - 4000 16000

2 Random 201 49 - - - 8116 32464

3 Random 176 49 25 - - 13341 53364

0 3 6 90

0 .2

0 .4

0 .6

0 .8

1

D istan e , m mс

Pow

er, a

.u.

123

15

3) Random distribution of cells and clusters

Scheme of cell’s distribution on waveguide

16

Power decay in waveguide with random cell distribution and random cluster of cells

Power vs distance for waveguide with core height 3 µm for random distribution of cells with different size (line 1) and random distribution of cluster of cells (line 2)

0 3 6 90

0 .2

0 .4

0 .6

0 .8

1

D ista n e , m mс

Pow

er, a

.u.

12

4 .9 50 .4 3

0 .4 8

№line

Cell distribution

Cell sizes (µm) Stotal, µm2

Vtotal, µm34x4x4 10x10x4 15x15x4 10x10x10 15x15x15

1 Random 176 49 25 - - 13341 53364

2 Random 176 - - 49 25 13341 136191

17

Conclusion

1)We have proposed a method to estimate the metal-tagged objects encountering evanescent field propagating in planar buried waveguides based on (Yb,Nb):RTP/RTP(001) system.

2) Based on our simulation results, it can be concluded that the contact area of the cells has main influence on the waveguide output regardless of the height of the cells.

3) This technique can work with virtually any metal-tagged cells.

4) We expect this technology to impact on cell counting applications in military medicine, in disaster settings, and in rural healthcare.

Thank you very much for your attention!!!