High speed ultra-broadband amplitude modulators with ultrahigh extinction >65 dB

Area of Science:

• Photonics and Optical Engineering
• Integrated Optics
• Quantum Information Technology

Background:

• Conventional Mach-Zehnder interferometers (MZIs) face limitations in extinction ratio and fabrication tolerance.
• Amplitude modulators (AMs) are crucial components in optical systems, particularly for quantum information processing.
• Broad spectral tunability and high extinction ratios are desired for advanced photonic applications.

Purpose of the Study:

• To experimentally demonstrate ultrahigh extinction ratio amplitude modulators (AMs) with broad spectral tunability.
• To investigate the performance of a cascaded Mach-Zehnder interferometer (CMZI) structure for AMs.
• To compare the performance of CMZI AMs using directional versus adiabatic couplers and analyze behavior under extreme conditions.

Main Methods:

• Fabrication and characterization of on-chip AMs based on a CMZI structure.
• Integration of electro-optic phase shifters for high-speed modulation.
• Experimental comparison between CMZI AMs utilizing directional and adiabatic couplers.
• Testing performance with non-ideal components like 95:5 split ratio couplers and unbalanced waveguide losses.

Main Results:

• Achieved ultrahigh extinction ratios exceeding 65 dB.
• Demonstrated electrical tunability across a 160 nm spectral range (1480-1640 nm) and a 95 nm range (1280-1375 nm).
• Investigated and analyzed the output optical phase modulation, providing insights for simultaneous amplitude and phase control.

Conclusions:

• The CMZI structure offers a viable path to ultrahigh extinction ratio amplitude modulators.
• The demonstrated AMs significantly alleviate fabrication tolerances for large-scale integrated photonics.
• These devices are promising for applications in quantum information processing and other advanced photonic systems requiring high-performance modulators.