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Optoelectronics Group Electronics Department University of Pavia

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  1. Optoelectronics GroupElectronics DepartmentUniversity 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 A. Sciré, IMEDEA, Palma de Mallorca, Spain

  2. 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 Semiconductor Ring Laser(SRL) MOTIVATION

  3. PD1 PD2 R MODE 2 MODE 1 L PD3 SRL Structure MATERIAL: AlGaAs/GaAs InP/InGaAsP RING RADIUS: 1mm PD1,2 LENGTH: 1mm PD3 LENGTH: 50-200μm FABRICATION LAS = 860nm Single Longitudinal Mode

  4. Photocurrent PD1 BIDIRECTIONAL CW BIDIRECTIONAL HO Photocurrent PD2 UNIDIRECTIONAL Frequency: 80-100MHz Dynamics:Experimental Results P-I CHARACTERISATION B: BIDIRECTIONAL C: UNIDIRECTIONAL

  5. EXPLICIT COUPLING BETWEEN THE TWO MODES (H. A. Haus, IEEE JQE, 1985) KD = DISSIPATIVE COUPLING KC = CONSERVATIVE COUPLING S, C = SELF/CROSS SATURATION COEFFICIENTS IMPORTANT TO UNDERSTAND SRL DYNAMICS Dynamics:Theoretical Model SLOWLY VARYING AMPLITUDE MEAN FIELD NORMALIZED RATE EQUATIONS

  6. Power of the two modes [a. u.] Time [s] Time [s] Dynamics:Simulations Results KD AND KC COEFFICIENTS CAN BE ADJUSTED TO FIT THE MODE OSCILLATION FREQUENCY OBSERVED IN THE EXPERIMENTS

  7. Experiment-Model Comparison S=1ns P=20ps S=0.0335 C=0.037 KD=0.00035 KC=0.0079 =3.5

  8. NEW RESULT IN SEMICONDUCTOR LASERS SRL Regimes Interpretation KC = LOCALISED REFLECTION IN THE CAVITY IT FAVOURS HARMONIC OSCILLATIONS KD = LOCALISED LOSS IN THE CAVITY IT FAVOURS UNIDIRECTIONALITY

  9. HARMONIC OSCILLATION INSTABILITY: DYE LASER F. C. Cheng, Phys. Rev. A, 1992 GAS LASER R. J. C. Spreew et al., Phys. Rev. A, 1990 Previous Results He-Ne LASER: R. J. C. Spreew et al., Phys. Rev. A, 1990

  10. Coherence Length Measurement Contrast Measurement Technique (non-conventional) Linewidth Measurement:Experimental Setup Low power coupled in SM fiber (~ 50-100nW)

  11. Bi-CW110 MHz Bi-CW UNI UNI38 MHz Schawlow-Townes limit Linewidth Measurement:Results LINEWIDTH ESTIMATION Linewidth ~ doubling in Bi-HO regime Mode power halving

  12. Experimental characterisation of semiconductor ring lasers (AlGaAs - InGaAsP) SRL theoretical model realisation and computer simulations Experiment-Model Fitting Linewidth first-time measurement in UNI and Bi-CW regimes (40-100MHz) SUCCESSFUL Conclusions

  13. Optical Spectrum Measures MODE SPACINGMEASUREMENT 13.6 GHz  Scale: 21.6 GHz/div

  14. SRL Structure SINGLE TRANSVERSAL MODE RIDGE STRUCTURE

  15. SRL Structure

  16. Cross-Correlation Measurement Linewidth Measurement:Mode Cross-Correlation

  17. Linewidth Measurement:Mode Cross-Correlation Interferometric Signal(Oscilloscope Trace) Cross-Correlation Vs. Autocorrelation