Improved Long-Term DC Drift in OH-Reduced Lithium Niobate Optical Intensity Modulators

Area of Science:

• Photonics and Materials Science
• Integrated Optics

Background:

• Optical intensity modulators are crucial for telecommunications.
• Long-term direct current (dc) drift limits the operational lifespan of lithium niobate (LiNbO3) modulators.
• This drift is often attributed to the presence of hydroxyl (OH-) ions in the substrate material.

Purpose of the Study:

• To investigate methods for reducing long-term dc drift in lithium niobate optical intensity modulators.
• To assess the impact of excluding OH(-) ions on modulator stability.
• To determine the potential for extended operational lifetimes.

Main Methods:

• Preparation of titanium-indiffused waveguides on commercial OH-free lithium niobate substrates.
• Fabrication of hermetically sealed optical modulators.
• Measurement and analysis of dc drift characteristics under operational conditions.

Main Results:

• Successful reduction of long-term dc drift was achieved by using OH-free lithium niobate substrates.
• Hermetically sealed modulators exhibited significantly improved stability.
• The observed drift suggests a potential for continuous operation exceeding 20 years at 50°C.

Conclusions:

• Exclusion of OH(-) ions is a key factor in enhancing the long-term stability of lithium niobate optical modulators.
• The developed fabrication process offers a viable path towards ultra-stable photonic devices.
• This advancement paves the way for more reliable and long-lasting optical communication systems.