Mach-Zehnder Modulators for Microwave Polarization Measurement in Astronomy Applications

Area of Science:

• Photonics and Optical Engineering
• Microwave Instrumentation
• Cosmology

Background:

• Traditional Mach-Zehnder modulators (MZMs) use LiNbO3, limiting integration.
• Near-infrared (NIR) frequency up-conversion is key for optical correlation and signal detection at 1550 nm.
• Wide-band applications like cosmic microwave background (CMB) study require advanced instrumentation.

Purpose of the Study:

• To evaluate and compare the performance of different Mach-Zehnder modulation technologies.
• To assess the suitability of InP-based integrated MZMs for microwave polarimetry.
• To investigate the impact of modulator choice on polarization measurement accuracy.

Main Methods:

• Characterization of modulation performances for commercial and InP-integrated MZMs.
• Integration of selected MZMs into a previously developed microwave polarimeter demonstrator.
• Comparative analysis of polarization measurement capabilities using different modulators.

Main Results:

• One commercial MZM exhibited higher bandwidth than previously reported.
• Three InP-integrated MZMs from Fraunhofer HHI were tested.
• Performance comparison revealed suitability of InP MZMs for microwave polarimetry applications.

Conclusions:

• InP-based integrated MZMs offer significant advantages in bandwidth, cost, and size.
• These integrated modulators are highly promising for wide-band applications, including CMB instrumentation.
• The study validates the use of advanced modulation technologies for enhanced microwave polarimetry.