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MZI Modulators

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Suresh Jat

This document discusses lithium niobate based Mach-Zehnder interferometer (MZI) modulators. It provides an introduction to lithium niobate, describing its properties and advantages for electro-optic applications. It then discusses the operating principles of MZI modulators for optical switching. The document outlines the design and simulation of an MZI modulator using lithium niobate, including the design parameters, layout, and simulation results showing the optical field and refractive index with applied voltages. It concludes that MZIs can operate at high data rates and future work could aim to improve performance parameters like insertion loss or switching voltage.

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Lithium Niobate Based MZI Modulators -By Suresh Chand Jat 2015PWC5398 M.Tech (WOC) MNIT Jaipur Supervisor Dr. M. Ravi Kumar Assistant Professor Dept. of ECE MNIT Jaipur
Outlines  Introduction to Lithium Niobate  MZI Modulator  MZI Performance Parameters  MZI Design Parameters  MZI layout  Simulation Results  Conclusion
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 Advantages of 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 loss Excess Loss Extinction Ratio SwitchingVoltage
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  OperatingWavelength – 1.3 um  SwitchingVoltage- 6.75V
MZI Layout
Simulation Results Optical Field when Electrode-2Voltage is 0 volt
Simulation Results Refractive index When Elecrode-2 Voltage is 0 volt
Simulation Results Field and RI graphWhen 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 graphWhen 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.
THANKYOU

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MZI Modulators