Second-harmonic-generation microsystem light source at 488 nm for Raman spectroscopy

Area of Science:

• Optics and Photonics
• Materials Science
• Spectroscopy

Background:

• Microsystem light sources are crucial for portable analytical instruments.
• Efficient generation of specific wavelengths, like 488 nm, is often challenging.
• Nonlinear frequency conversion offers a pathway to compact, wavelength-specific light sources.

Purpose of the Study:

• To demonstrate a compact microsystem excitation light source emitting at 488 nm.
• To achieve efficient second-harmonic generation (SHG) for a 488 nm output.
• To develop a stable and compact light source suitable for Raman spectroscopy.

Main Methods:

• Utilized a diode laser emitting at 976 nm as the fundamental source.
• Employed a periodically poled lithium niobate (PPLN) waveguide crystal for direct single-pass nonlinear frequency conversion.
• Integrated the components onto a micro-optical bench with advanced thermal management.

Main Results:

• Achieved efficient second-harmonic generation, producing 56 mW at 488 nm from 217 mW fundamental power.
• Demonstrated a high conversion efficiency of 26% for the nonlinear process.
• The device exhibited excellent power stability below 1% and a compact footprint (25 mm x 5 mm).

Conclusions:

• A highly efficient and compact 488 nm light source was successfully realized.
• The demonstrated microsystem is wavelength-stabilized and suitable for demanding applications like Raman spectroscopy.
• This development advances the potential for portable and high-performance spectroscopic instrumentation.