Transcript No Slide Title - Faculdade de Engenharia da Universidade do Porto

Characterization of Fiber Bragg Gratings for
Dispersion Compensation
http://paginas.fe.up.pt/~ee99113/
L. M. Ramos 1,2, R. P. Ramos 1,2, H. M. Salgado 1,2
1
INESC Porto - Unidade de Optoelectrónica e Sistemas Electrónicos , 4169-007
Porto, Portugal
2 Faculdade de Engenharia da Universidade do Porto, 4200-465 Porto, Portugal
OBJECTIVES:
MEASUREMENT SETUP:
• Characterization of Fiber Bragg Gratings
• Implementation of measurement setup
• Software for control and data acquisition
• Data analysis: delay, bandwidth, ripple
Network Analyzer operation:
• Continuous Wave (CW) mode
• Control of sweep time
DELAY MEASUREMENT:
• Control of number of points


360 f mod
Fig. 2: Setup for measurement of amplitude and group delay, with the Phase Shift method.
DISPERSION COMPENSATION:
Input: Long
Decreasing
grating period
(Chirp)
Long
Short 
Output: Compressed
Pulse
DEVELOPED SOFTWARE:
Short
Fig. 1: Dispersion compensation using a chirped Fiber Bragg Grating.
Fiber Bragg Gratings are passive components that work as
optical filters. Their singular characteristic makes them useful
for dispersion compensation.
Underlying intramodal dispersion is the broadening of the
pulse. A chirped Bragg grating introduces different delays at
different frequencies, compressing the pulse.
Fig. 4: Measurement with real
time data presentation.
Fig. 3: Software to control the system, and data acquisition.
FIBER BRAGG GRATING:
RIPPLE MEASUREMENT:
SPECIFICATIONS:
• Wavelength Bandwidth: 1520 nm – 1570 nm
• Wavelength Resolution: 1 pm
• Modulation Frequency: 300 kHz – 3 GHz
• Spectral Resolution: 16 pm (1 GHz)
• Group Delay Resolution: 0.28 ps (1 GHz)
Fig. 5: Add-on for quickly calculate
Reflectivity or Group Delay ripple.
either
Fig. 7: Fiber with two gratings written.
Fig. 6: Data analysis – Group delay ripple.
Fig. 8: High resolution characterization
for the second grating.
CONCLUSIONS:
A measurement setup was implemented for characterization of the amplitude and group delay
parameters of Fiber Bragg Gratings.
Efficient control of the setup with a user-friendly interface was achieved. Characterization of
Fiber Bragg Gratings is carried out with high-resolution and fast processing.
ADDITIONAL WORK:
Fig. 8: Generic software for data
acquisition from the Network Analyzer.
ACKNOWLEDGEMENTS
L. M. Ramos and R. P. Ramos would like to acknowledge Prof. A.
Teixeira for his collaboration and are thankful for the grant conceded by
the Program PRODEP III - Medida 3.