DEBASMIT DAS ENROLLMENT NO. – 10115039 BATCH E3

DETAILS ABOUT MY INTERNSHIP  TYPE – RESEARCH INTERNSHIP  PLACE – ECOLE POLYTECHNIQUE DE MONTREAL  FIELD – PHOTONICS  GUIDE – DR. RAMAN KASHYAP  LAB- ADVANCED PHOTONICS CONCEPTS LABORATORY  DURATION – 13 TH MAY TO 19 TH JULY, 2013

CONTENTS OF MY INTERNSHIP

 FABRICATION OF A 4-PORT OPTICAL FIBER COUPLER  EXPERIMENTAL AND THEORITICAL ANALYSIS OF SURFACE PLASMON DEVICES (SPR) BASED ON OPTICAL FIBER

FABRICATION OF A 4-PORT OPTICAL FIBER COUPLER  AIM OF THIS PROJECT IS TO BUILD A COUPLER THAT CAN BE USED MULTIPURPOSELY FOR DIFFERENT PROJECTS IN THE FUTURE.

 I APPLIED THE COUPLER TO OBTAIN THE REFLECTION AND TRANSMISSION SPECTRUM OF A TILTED FIBER BRAGG GRATING.

 DETAILS ON THESE IN THE COMING SLIDES……

FIBER OPTIC COUPLER

Coupler used to direct light into the Fiber Bragg Grating.

L C =Coupling Length ; L W = Waist Length ; L T = Taper length

P 1-3 (Power in wave guide 1 to 3) = cos 2 (kz) P 2-4 (Power in wave guide 2 to 4) = sin 2 (kz) Plot of power P 1-3 (red) P 2-4 (green) with distance along coupling length

FBG and tilted FBG

 Resonance condition for FBG λ B = 2nt For tilted FBG the condition holds as λ B = 2nt cos (x) where x is the angle of tilt But why is the tilted FBG?

Because my fiber is DCF (double clad fiber)

Schematic of the Coupler I am to produce

Steps

 Etching of two DCF fibers around 15 cm length  Twisting of the two fibers along the etched portion.

 Fixing the coupler to a platform to make it ready for measurements  Characterization of the coupler and observing the spectrum of the tilted FBG

DCF before being etched DCF after being etched

Characterization

 Excessive Loss = -10 log(P1+P2/Pin)  CR = P2/P1+P2 x 100 % (Coupling Ratio)  For 6 Twists – P in = 12.35dBm

P 1 =10.45 dBm P 2 =-32.45 dBm So excessive Loss = 1.5497 dB CR=0.005688 %

Reflection and Transmission Spectrum

SURFACE PLASMON RESONANCE  AIM OF THIS PROJECT IS SIMULATION AND ANALYSIS OF SPR ON A NOVEL H-SHAPED FIBER  SIMULATION HAS BEEN DONE IN MATLAB  PURPOSE OF SIMULATION IS TO ANALYSE AND COMPARE WITH EXPERIMENTAL RESULTS

PHENOMENON OF SPR

k*n g *sinθ = k((n s 2 *ε m )/( n s 2 + ε m ))^0.5 MOMENTUM TRANSFER CONDITION

APPLICATION

 As a biosensor or a chemical sensor  As refractive index of sensing medium changes so will the resonance wavelength  So the resonance wavelength can plotted with refractive index and this calibration is used to create biosensor  It can indirectly be used to measure concentration of analyte which perturbs refractive index  ADVANTAGE : Very high sensitve sensors ~ 3000 nm/RIU . Apt for the nano world.

The Special H-shaped fiber

Why H-shaped Fiber?

 Birefringent fiber with elliptical core  Two orthogonal single modes with no interference in visible region.

 Can be used to measure two quantities simultaneously  But for now analysis is done for one axis that is the axis along the cleavage….

N-Layer Model Parameters

 N=3 for our cases  n1=core n2=metal n3=dielectric sensing medium  Core diameter =10 nm Metal thickness (gold) =50 nm and Dielectric thickness = 25 nm

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SPECIAL THANKS TO MITACS FOR FUNDING THE INTERNSHIP