Lithium Niobate Based MZI Modulators

-By Suresh Chand Jat

2015PWC5398

M.Tech (WOC)

MNIT Jaipur

SupervisorDr. M. Ravi KumarAssistant ProfessorDept. of ECEMNIT Jaipur

Outlines

Introduction to Lithium NiobateMZI ModulatorMZI Performance ParametersMZI Design ParametersMZI layoutSimulation ResultsConclusion

Introduction to Lithium Niobate(LiNbO3)

Lithium niobate is a colourless solid insoluble in water. It has a trigonal crystal system, which lacks inversion symmetry and displays ferroelectricity, Pockels effect, piezoelectric effect, photoelasticity and nonlinear optical polarizability.

Lithium niobate has negative uniaxial birefringence which depends slightly on the stoichiometry of the crystal and on temperature. It is transparent for wavelengths between 350 and 5200 nanometers

LiNbO3 Properties

Main Advantagesof LiNbO3

LiNbO3 is an electroptic material Components compacts. Active components ( modulators …). Low driving voltage. High data rate (20-40 GHz ) Good compatibility with optical fibres Pigtailling : relatively easy butt coupling ). Wafer fabrication. Light fabrication technology (<5 mask layers ).…..

Mach-Zehnder Interferometer (MZI) Modulator

In optical switching, induced phase shift by applied voltage can be converted to an amplitude variation by using an interferometer

Interferometer is a device that interferes two waves of the same frequency but different phase

Compared to Directional coupler MZI offers a higher modulation speed for a given drive voltage and provides a higher extinction ratio.

MZI Performance Parameters

Insertion lossExcess LossExtinction RatioSwitching Voltage

MZI Design Parameters

Software - OptiBPM Crystal –Lithium Niobate

Crystal cut-Z Propagation Direction-Y

Dielectric Material –Air Profile – TiLiNbO3 Wafer Dimension

Length-33000 um Width- 100 um

Electrode Length- 11500 -21500 um Operating Wavelength – 1.3 um Switching Voltage- 6.75 V

MZI Layout

Simulation Results

Optical Field when Electrode-2 Voltage is 0 volt

Simulation Results

Refractive index When Elecrode-2 Voltage is 0 volt

Simulation Results

Field and RI graph When Elecrode-2 Voltage is 0 volt

Simulation Results

Optical Field When Elecrode-2 Voltage is 6.75 volt

Simulation Results

Refractive index When Elecrode-2 Voltage is 6.75 volt

Simulation Results

Field and RI graph When Elecrode-2 Voltage is 6.75 volt

Conclusion

MZI is widely used optical device performs the optical modulation and switching operations.

Operate at 20-40 GHz It can be possible to design MZI for visible band I will try to improve one of the MZI performance

parameter like insertion loss or switching voltage.

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