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Optoelectronics Group Electronics Department University of Pavia. Operating Regimes And Modelling Of Single Mode Monolithic Semiconductor Ring Lasers G. Giuliani, R. Miglierina , S. Donati, University of Pavia, Italy M. Sorel, P. J. R. Laybourn, University of Glasgow, UK - PowerPoint PPT Presentation
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Optoelectronics GroupElectronics Department
University of Pavia
Operating Regimes And Modelling Of Single Mode Monolithic Semiconductor Ring Lasers
G. Giuliani, R. Miglierina, S. Donati, University of Pavia, ItalyM. Sorel, P. J. R. Laybourn, University of Glasgow, UK
A. Sciré, IMEDEA, Palma de Mallorca, Spain
Semiconductor Ring Laser(SRL)
MOTIVATION
Easy integration devices (no mirrors or Bragg gratings are required)
Possible applications:
Gyroscopy, Filters, Wavelength Converters, MUX/DEMUX
Application in OEICs (Opto-Electronic Integrated Circuits):
Optical Gating, Optical Memories
SRL Structure
R
L
PD1 PD2
PD3
MODE 2
MODE 1
MATERIAL: AlGaAs/GaAs
InP/InGaAsP
RING RADIUS: 1mm
PD1,2 LENGTH: 1mm
PD3 LENGTH: 50-200μm
FABRICATION
LAS = 860nm
Single Longitudinal
Mode
Dynamics:Experimental Results
P-I CHARACTERISATION
BIDIRECTIONAL
CW
BIDIRECTIONAL
HO
B: BIDIRECTIONAL
C: UNIDIRECTIONAL
UNIDIRECTIONAL
Photocurrent PD1
Photocurrent PD2
Frequency: 80-100MHz
Dynamics:Theoretical Model
SLOWLY VARYING AMPLITUDE MEAN FIELD NORMALIZED RATE EQUATIONS
S, C = SELF/CROSS SATURATION COEFFICIENTSEXPLICIT COUPLING BETWEEN THE TWO MODES (H. A. Haus, IEEE JQE,
1985)
KD = DISSIPATIVE COUPLING
KC = CONSERVATIVE COUPLINGIMPORTANT TO UNDERSTAND SRL DYNAMICS
Dynamics:Simulations Results
KD AND KC COEFFICIENTS CAN BE ADJUSTED TO FIT THE MODE OSCILLATION FREQUENCY OBSERVED IN THE EXPERIMENTS
Time [s]
Time [s]
Pow
er
of
the t
wo m
odes
[a.
u.]
Experiment-Model Comparison
S=1ns
P=20ps
S=0.0335
C=0.037
KD=0.00035
KC=0.0079
=3.5
SRL Regimes Interpretation
NEW RESULT IN SEMICONDUCTOR LASERS
KC = LOCALISED REFLECTION IN THE CAVITY
KD = LOCALISED LOSS IN THE CAVITY
IT FAVOURS HARMONIC OSCILLATIONS
IT FAVOURS UNIDIRECTIONALITY
Previous Results
DYE LASER F. C. Cheng, Phys. Rev. A, 1992
GAS LASER R. J. C. Spreew et al., Phys. Rev. A, 1990
HARMONIC OSCILLATION INSTABILITY:
He-Ne LASER: R. J. C. Spreew et al., Phys. Rev. A, 1990
Coherence Length Measurement
Linewidth Measurement:Experimental Setup
Low power coupled in SM fiber (~ 50-100nW)
Contrast Measurement Technique (non-conventional)
Linewidth Measurement:Results
LINEWIDTH ESTIMATION
Linewidth ~ doubling in Bi-HO regime
Bi-CW110 MHz
UNI38 MHz
Mode power halving
21
PFP
Schawlow-Townes limit
Bi-CW UNI
Conclusions
Experimental characterisation of semiconductor ring lasers
(AlGaAs - InGaAsP)
•
SRL theoretical model realisation and computer simulations•
Experiment-Model Fitting• SUCCESSFUL
Linewidth first-time measurement in UNI and Bi-CW regimes (40-100MHz)•
Optical Spectrum Measures
Scale: 21.6 GHz/div
MODE SPACINGMEASUREMENT
13.6 GHz Rn
c
2
SRL Structure
RIDGE STRUCTURE SINGLE TRANSVERSAL MODE
SRL Structure
Linewidth Measurement:Mode Cross-Correlation
Cross-Correlation Measurement
Linewidth Measurement:Mode Cross-Correlation
Interferometric Signal(Oscilloscope Trace)
Cross-Correlation Vs. Autocorrelation