Mach-Zehnder modulator

A Mach-Zehnder modulator is an optical member for light in its intensity to modulate .

Schematic structure of a Mach-Zehnder modulator. BS: beam splitter, M: mirror.

Transmission of a Mach-Zehnder modulator as a function of the applied voltage.

The modulator is a Mach-Zehnder interferometer , in one arm of which an electro-optical element ( Pockels or Kerr cell ) is placed in order to generate a phase shift between the two interferometer arms . The intensity at the output of the interferometer varies depending on the value of the phase shift. The transmission T of the modulator is calculated according to:

${\displaystyle T(U)=\cos ^{2}\left({\frac {\varphi _{0}}{2}}-{\frac {\pi U}{2U_{\pi }}}\right)}$.

U is the voltage applied to the electro-optical element , is the voltage at which maximum transmission is achieved and a constant phase value that is given by the structure of the modulator. ${\displaystyle U_{\pi }}$ ${\displaystyle \varphi _{0}}$

literature

• Bahaa EA Saleh, Malvin C. Teich: Fundamentals of Photonics . Wiley & Sons, 2007 ISBN 0-471-35832-0 .

Web links

• Interactive display of the characteristic curve of the Mach-Zehnder modulator