intensity

Hello.

An electro-optic switch is a device used in integrated fibre optics. The device is based on Mach-Zehnder interferometer made by Titanium diffusion in Lithium Niobate substrate. The switching between the ports is achieved by an electro-optic effect within such structure. Voltage, applied to the electrodes deposited on the integrated Mach-Zehnder interferometer, creates an electric field distribution within the substrate, which consequently changes its refractive index. If properly designed, the induced change in the refractive index leads to different coupling between individual ports.
You may go through

Mach-Zehnder Interferometer Switch

I hope this will help you.
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I also want to add that External modulators offer a way to reduce or eliminate chirp because the laser source is held in the narrow linewidth, steady-state mode. External modulator is typically either a LiNbO3 modulator or an electroabsorptive modulator. In this lesson the chirp induced by the LiNbO3 is analyzed based on the voltage of operation.The modulator is operating in the quadrature mode. This means that the bias voltage places the modulator at the midpoint of the optical response curve, and therefore, the intensity is at half of its peak value. The parameters utilized to setup the modulator. The extinction ratio is set to 200dB to avoid any chirp caused by asymmetric Y-branch waveguide. The modulator is set to work in a non-normalized way, which means the electrical input signal will not be normalized.

You may refer to

Mach-Zehnder Interferometer Switch

Four Channel Mach-Zehnder Multi/Demultiplexer

Chirp in Mach-Zehnder Lithium Niobate Modulators

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