Silicon nitride PIC-based multi-color laser engines for life science applications

Area of Science:

• Photonics
• Microscopy Engineering
• Optical Engineering

Background:

• Microscope imaging requires precise control of multiple excitation wavelengths.
• Current multi-color laser engines often rely on bulky discrete optical components.
• Miniaturization is crucial for advanced and portable microscopy systems.

Purpose of the Study:

• To implement a compact multi-color laser engine utilizing silicon nitride photonic integrated circuit (PIC) technology.
• To integrate four distinct fluorophore excitation wavelengths (405 nm, 488 nm, 561 nm, 640 nm) into a single, miniaturized system.
• To enable flexible light delivery for diverse microscope imaging modalities.

Main Methods:

• Fabrication of a silicon nitride photonic integrated circuit for laser wavelength combination and splitting.
• Integration of a directional coupler for light multiplexing.
• Utilization of thermally actuated Mach-Zehnder interferometers for variable optical attenuation and fiber switching.
• Characterization of spectrally resolved performance for individual PIC devices and the overall system.

Main Results:

• Achieved a two orders of magnitude reduction in optical volume compared to discrete optics.
• Demonstrated light multiplexing with variable attenuation across two output fibers.
• Reported total insertion losses of approximately 6 dB at 488 nm, 561 nm, and 640 nm.
• Identified areas for improvement in insertion loss at 405 nm.

Conclusions:

• Silicon nitride PIC technology offers a highly effective solution for miniaturizing multi-color laser engines.
• The developed engine provides a compact and versatile light source for advanced microscopy.
• Further optimization can enhance performance, particularly at shorter wavelengths.