Is anyone knowledgeable on Mach Zehnder Modulators?

[njlenoir]

I am conducting research on a LiDAR Design for my University, and currently building an optical IQ Modulator, consisting of two Mach-Zehnder Modulators (MZM's) and a Phase Modulator.

I have measured the Power Transfer curve of both MZM's, and both curves read as Sinusoidal curves as expected. However, both MZM's are slightly phase shifted from the origin in different directions (One slightly leads the origin, the other lags).

I have tried using the DC bias ports on the MZM's, which did not affect the phase shift. Do any experts know how I might phase shift the MZM's to the origin?

 

[D.A.(Tony)Stewart]

https://chatgpt.com/c/a869f620-46f3-4d30-b4c5-11be50dcc78a

FWIW

Phase shifting in Mach-Zehnder Modulators (MZMs) can be achieved through several techniques:

1. Thermal Phase Shifting: Uses heating elements to change the refractive index, altering the optical path length and phase. It's simple and low-cost but slow and power-consuming.
2. Electro-Optic Phase Shifting: Applies an electric field to an electro-optic material (like Lithium Niobate) to change its refractive index via the Pockels effect. This method offers fast response times but requires high voltage and can be complex.
3. Carrier Injection/Depletion: Involves injecting or depleting carriers in semiconductor waveguides (e.g., silicon) to change the refractive index. It can be integrated on-chip with moderate speed but has a limited phase shift range and introduces loss.
4. Micro-Electro-Mechanical Systems (MEMS): Uses mechanical movement of components to alter the optical path length. It provides large phase shifts with low power consumption but can be slower and less reliable.
5. Plasma Dispersion Effect: Changes the refractive index by varying free carrier concentration in materials like silicon. It's fast and compatible with silicon photonics but introduces some loss and has a limited phase shift range.