Integrated Lloyd's mirror on planar waveguide facet as a spectrometer

Area of Science:

• Photonics and Spectroscopy
• Integrated Optics
• Optical Metrology

Background:

• Fourier transform spectrometers (FTS) are crucial for spectral analysis but can be complex and costly.
• Achieving stable interferograms is essential for high-fidelity spectral measurements.
• Integrated photonic devices offer miniaturization and stability advantages for optical instrumentation.

Purpose of the Study:

• To propose and demonstrate a novel, low-cost, and highly stable Fourier transform spectrometer.
• To leverage integrated photonics and Lloyd's mirror configuration for enhanced interferogram stability.
• To achieve a practical spectral resolution for broadband applications.

Main Methods:

• A planar waveguide coupled to fiber injection spatially disperses the optical beam.
• A Lloyd's mirror configuration is implemented using total internal reflection on a diced glass surface integrated into the chip.
• The resulting interferogram is imaged onto a near-infrared camera for analysis.

Main Results:

• A very stable interferogram is achieved due to the integrated optical design.
• The spectral resolution reached is approximately \(\lambda/\Delta\lambda = 80\) in the O to L wavelength bands (approximately 1260-1675 nm).
• Contrast and fringe period are tunable by adjusting fiber position and optimizing camera parameters.

Conclusions:

• The proposed Fourier transform spectrometer offers a cost-effective and stable solution for spectral analysis.
• The integrated photonic approach simplifies the optical setup and enhances robustness.
• This device is suitable for applications requiring broadband spectral measurements with moderate resolution.