Embed Size (px)
Citation preview
Photon2 InternshipPENN STATE UNIVERSITY
Materials Research Lab
June 2005
Paul Longwell
Dr. Venkatraman GopalanCooperating Faculty
Topic:Fiber Optic Communication
Focus – Signal Modulation
(Encoding Information to be Sent)
Fiber Optic CommunicationBegins With Laser Light
The light is produced by a tiny diode.
ww
w.g
cse
.co
m
Fiber Optic CommunicationInformation (Voice, Websites, Etc) is
Encoded into Pulses.
First, a laser beam is split into two identical beams.
How?
Fiber Optic CommunicationInformation is Encoded into Pulses
Each beam travels an identical path and then they are recombined, but….
ww
w.p
ho
ton
ics.
com
Fiber Optic CommunicationInformation is Encoded into Pulses
…one beam must pass through an ELECTRO-OPTIC crystal.
Fiber Optic CommunicationInformation is Encoded into Pulses
When an electronic signal is delivered to the crystal, the light wave shifts.
Many layers in a thin device!
200
2 d
en
Be
ste
n, e
t al
Fiber Optic CommunicationInformation is Encoded into Pulses
When the light waves recombine, the result is ON (pulse) or OFF (no pulse)
The ON and OFF signals carry the code of information!
Identical Waves
One Shifted Wave
ON
OFF
Fiber Optic CommunicationTo study the splitting and recombining of a
laser beam, I tried it!
Mach-Zehnder
Inteferometer
Fiber Optic CommunicationRecombining the Beams Perfectly is
Challenging!
Good
GoodBad
Bad
Fiber Optic Communication“Perfectly” Aligned!
Good
Good
Fringes Seen On the White
Paper
Fiber Optic CommunicationHow do the laser pulses carry the information
from one place to another?
ww
w.c
orn
ing
.co
m
Fiber Optic Communication
Fiber optic cables contain several layers:
Fiber Optic Communication
Total Internal Reflection allows the light to remain in the fiber optic cable as it travels.
Fiber Optic Communication
After the light has traveled through the cable, the initial encoding process is essentially reversed
and the information is delivered.
ww
w.c
orn
ing
.co
m
Other Internship Images
A diffraction grating used in laser experiments
Other Internship Images
Other Internship Images
Thank YouDr. Venkatraman Gopalan
Sava Denev
Lili Tian
Aravind Vasudevarao
