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High-Resolution Optical Spectrum Analysis Photonic Technologies Group Aragon Institute of Engineering Research University of Zaragoza
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High-Resolution Optical Spectrum AnalysisPhotonic Technologies GroupAragon Institute of Engineering ResearchUniversity of Zaragoza
High-Resolution Optical Spectrum Analysis 2Panticosa, September 2004
Outline of the presentation
Introduction: HR-OSA & Microwave Photonics Optical Spectrum Analysis (OSA)
Fundamental OSA concepts High-resolution OSA techniques
The BOSA technique Demonstration of BOSA system Discussion about HR-OSA applications Questions, comments, etc.
High-Resolution Optical Spectrum Analysis 3Panticosa, September 2004
High-resolution OSA & Microwave PhotonicsElectrical Power
GHz
1 GHz
Optical Power
THz1931550 nm Optical Power
GHz
8 pm
1 fm 125 kHz
1 Mhz 8 fm
1 pm 125 MHz
1 GHz 8 pm
1 nm 125 GHz
1 THz 8 nm
High-Resolution Optical Spectrum Analysis 4Panticosa, September 2004
OSA Fundamentals
Basic principles of operation Block diagram Optical filtering principles
Key features Spectral resolution Spectral range Dynamic range Wavelength accuracy: absolute, relative. Others: measuring speed, polarization dependence, …
High-Resolution Optical Spectrum Analysis 5Panticosa, September 2004
OSA block diagram
Input Signal
Optical detection
Tuning Control
Optical filtering
Wavelength tuning
Spectral Resolution
Spectral Range
Dynamic Range
Measuring speed
Sensitivity
Wavelength accur.
High-Resolution Optical Spectrum Analysis 6Panticosa, September 2004
Input Signal
Optical detection
Tuning Control
Optical filtering
Wavelength tuning
OSA Optical Filtering Methods
Diffraction grating Fabry-Perot Homodyne Interferometry Heterodyne Interferometry Others: non-linear effects, …
Spect. Resol.
Spect. range
Dyn. range
D-G Low High High
F-P High Low High
Ho-Interf. High Low/High Low
He-Interf. High Low/High Low
Band-pass optical filtering
Interferometric methods
High-Resolution Optical Spectrum Analysis 7Panticosa, September 2004
OSA Optical Filtering Methods
Fabry-Perot
Input Signal
Optical detection
Tuning Control
Optical filtering
Wavelength tuning
High-Resolution Optical Spectrum Analysis 8Panticosa, September 2004
OSA Optical Filtering Methods
Diffraction grating
Input Signal
Optical detection
Tuning Control
Optical filtering
Wavelength tuning
High-Resolution Optical Spectrum Analysis 9Panticosa, September 2004
OSA Optical Filtering Methods Homodine interferometry
Michelson interferometry
High-Resolution Optical Spectrum Analysis 10Panticosa, September 2004
OSA Dynamic RangeInput Signal
Optical detection
Tuning Control
Optical filtering
Wavelength tuning
Power
WavelengthPower
Wavelength
Band-pass optical filtering
Interferometric methodsNo-signal Null detected power
Gain adjustment allowed
No-signal High detected power
No gain adjustment
Higher noise level
High-Resolution Optical Spectrum Analysis 11Panticosa, September 2004
HR-OSA: Heterodyne Interferometry
Input signal
Localoscillator(fixed wl.)
ElectricalSpectrumAnalyzer
Fast detector
Input signal
Tunablelocaloscillator
Signalanalysis
Fast detector
Tuningcontrol
Fixed wavelength l.o. Narrow spectral range (< 0.5 nm) Low dynamic range Good absolute wl. reference
Tunable l.o. Large spectral range (100 nm) Low dynamic range Wl. reference limited by
tunable laser
High-Resolution Optical Spectrum Analysis 12Panticosa, September 2004
Power
Wavelength
OSA SensitivityInput Signal
Optical detection
Tuning Control
Optical filtering
Wavelength tuning Band-pass optical filtering
Interferometric methods
Broad spectrum sources:
Increased resolution means less detected power
Local oscillator in heterodyning methods may provide extra power Fast detection generally means low sensitivity
High-Resolution Optical Spectrum Analysis 13Panticosa, September 2004
Outline of the presentation
Introduction: HR-OSA & Microwave Photonics Optical Spectrum Analysis (OSA)
Fundamental OSA concepts High-resolution OSA techniques
The BOSA technique Demonstration of BOSA system Discussion about HR-OSA applications Questions, comments, etc.
High-Resolution Optical Spectrum Analysis 14Panticosa, September 2004
The BOSA system
Tunablelaser
PMF
Input signal
Control PC
Display&Interface
D+ADC
Pol.
BOSAcore
GPIB bus
High-Resolution Optical Spectrum Analysis 15Panticosa, September 2004
BOSA principle of operation
Input signal: unknown spectrum
Probe signal: tunable laser
Measured signal: revealed spectrum
Nonlinear (SBS) interaction
Patent: WO2004044538
High power in the laser beam gives high SBS gain:
Good sensitivity together with high resolution
Effective resolution:
~ 10 MHz or ~0.08 pm
High-Resolution Optical Spectrum Analysis 16Panticosa, September 2004
Spectrum of a tunable laser with side modes
28.5 pm
BOSA measurement example
High-Resolution Optical Spectrum Analysis 17Panticosa, September 2004
Non linear effects in a SOA18 pm
~ 1 GHz
High-Resolution Optical Spectrum Analysis 18Panticosa, September 2004
Two differentlasers
2 pm
~ 150 MHz
High-Resolution Optical Spectrum Analysis 19Panticosa, September 2004
PRBS (2.5 Gb/s) optical spectrum (uncalibrated)
High-Resolution Optical Spectrum Analysis 20Panticosa, September 2004
All 1’s pattern (2.5 Gb/s) optical spectrum (uncalibrated)
High-Resolution Optical Spectrum Analysis 21Panticosa, September 2004
Outline of the presentation
Introduction: HR-OSA & Microwave Photonics Optical Spectrum Analysis (OSA)
Fundamental OSA concepts High-resolution OSA techniques
The BOSA technique Demonstration of BOSA system Discussion about HR-OSA applications Questions, comments, etc.
High-Resolution Optical Spectrum Analysis 22Panticosa, September 2004
Outline of the presentation
Introduction: HR-OSA & Microwave Photonics Optical Spectrum Analysis (OSA)
Fundamental OSA concepts High-resolution OSA techniques
The BOSA technique Demonstration of BOSA system Discussion about HR-OSA applications Questions, comments, etc.
High-Resolution Optical Spectrum Analysis 23Panticosa, September 2004
Applications of HR-OSA in Microwave Photonics
Electrical Power
GHz
1 GHz
Optical Power
GHz
8 pm
Signal spectrum monitoring
Optical power vs. Electrical power spectra
Essentially the same information but…
There are some differences: Optical frequency modulation (laser chirp)
not shown in RF spectrum Dispersion effects in optical fibers (phase)
not shown in OSA (power spectrum)
RF optical synthesis monitoring (?)
High-Resolution Optical Spectrum Analysis 24Panticosa, September 2004
Outline of the presentation
Introduction: HR-OSA & Microwave Photonics Optical Spectrum Analysis (OSA)
Fundamental OSA concepts High-resolution OSA techniques
The BOSA technique Demonstration of BOSA system Discussion about HR-OSA applications Questions, comments, etc.
High-Resolution Optical Spectrum Analysis 25Panticosa, September 2004
PRBS (2.5 Gb/s) optical spectrum (uncalibrated)
