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Intoduction to VCSEL Device Simulation

Intoduction to VCSEL Device Simulation. Mou Zongying 07-06-2004. VCSEL Device Simulation. Introduction Basic concepts of Laser and semiconductor Physical model of VCSEL device Computing optical mode Numerical simulation Simulation results. Introdction. VCSEL:

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Intoduction to VCSEL Device Simulation

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  1. Intoduction to VCSEL Device Simulation Mou Zongying 07-06-2004

  2. VCSEL Device Simulation • Introduction • Basic concepts of Laser and semiconductor • Physical model of VCSEL device • Computing optical mode • Numerical simulation • Simulation results

  3. Introdction • VCSEL: vertical-cavity surface-emitting laser (semiconductor laser device, diode laser) • Telecomunications, Pumping source • Wave length : from infrared to visible etched mesa VCSEL 980nm Buried tunnel junction(BTJ) VCSEL 1300nm,1550nm • Material: ALGaAs(GaAs),InGaAsP(InP) • Simulators are needed to explore the design parameter for an optimum solution—low cost and short time for a design cycle

  4. Basic Concepts of Laser • Laser

  5. Requirements for Laser Action • Population inversion

  6. Basic Concepts of Semiconductor • There are three types of conductors . Insulaters .Metals .Semicondctors

  7. Energy Band for Solid • Metals . Overlapping energy bands or vary small gap . Electrons in conduction band • Semiconductors . Small energy gap <2ev . Some electrons in conduction band • Insulators . Large energy gap . No electrons in conduction band

  8. Physical Model of VCSEL • Diode laser devices – history • Physical Model of VCSEl • Schematic of two kinds of VCSEL .Etched Mesa .BTJ • Maxwell´s equation • Laser device simulation

  9. Diode Laser Devices • First working device appeared in 1962, at low temperature • Structure containing several semiconductor layers In 1969, at room temperature • After 1990, employed BTJ which causes a transverse waveguiding--stable transverse mode profile and small threshold current

  10. Physical Model of VCSEL • Time Dependent Model (Finite Difference Time Domain) in 1995 • Stationay Model (Finite Difference Method) in 1995 • Microscopic VCSEL Model in 1998 • Isothermal Electric model in 1999 • Method of Lines in 2001

  11. Etched Mesa VCSEL Schematic Etched Mesa VCSEL. DBR( distributed Bragg Resonator) Etched Mesa VCSEL(electron micrograph)

  12. Etched Mesa VCSEL

  13. BTJ VCSEL • Schematic Buried Tunnel Junction VCSEL

  14. Etched Mesa and BTJ VCSEL • Schematic cross section of two types of VCSEL

  15. Maxwell´s Equation • Maxwell´s eq. and material eq.

  16. Maxwell wave equation • for J=0

  17. Maxwell wave equation Separate Eigenvalue problem Frequency Normalization

  18. Laser Device Simulation Dielectric fuction Mechanism: . Direct interband absorption . Indirect interband absorption . Free carrier absorption . Interconduction band and intervalence band absorption

  19. Laser Device Simulation Photon rate eq. Where Skis the photon number Rkis spontaneous emmission wk‘‘ is the net modal rate change

  20. Computing Optical Mode • Open Cavity . Only the innerboundary Structure determines the optical mode . Outerboundary is an absorber (no backscattering)

  21. Computing Optical Mode • Variational function

  22. Computing Optical Mode • Rotation symmetric

  23. Computing Optical Mode • Variational function for axi-symmetric case

  24. Computing Optical Mode • Boundary condition

  25. Numerical Simulation • Jacobi-Davidson QZ iteration method • Biconjugate gradient stabilished method (BiCGstab) is used to solve Jacobi correction equation and speed up the convergence • Software: LUM12 mode solver package

  26. Simulation Result • The intensity of k(z) for the fundermental longitudinal VCSEL mode (Etched Mesa)

  27. Simulation Result • Foundmental mode (BTJ)

  28. Simulation Result • Higher mode (BTJ)

  29. 3D Numerical Simulation • Edge finite elements for solving 3D-Maxwell equation . Shape function are vectors . Unknows now along the edge . Natural elements for Maxwell´s equation . Restriction: domain has to be convex

  30. Thanks for your attendance!

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