Broadside coupling to long-range surface plasmons in metal stripes using prisms, particles, and an atomic force...

Area of Science:

• Photonics and Plasmonics
• Optical Engineering
• Materials Science

Background:

• Investigating techniques for efficient optical coupling to surface plasmon waves is crucial for developing advanced photonic devices.
• Long-range surface plasmon waves (LRSPW) propagating along metal stripes offer potential for miniaturized optical circuits.
• Existing coupling methods can be complex and may limit measurement accuracy.

Purpose of the Study:

• To investigate and compare techniques for broadside coupling to LRSPW.
• To develop a more accessible and higher-quality method for measuring LRSPW attenuation.
• To explore the applicability of the proposed technique to other waveguide systems.

Main Methods:

• Theoretical modeling of plane wave coupling to LRSPW.
• Experimental implementation of a baseline prism-based coupling technique.
• Development and testing of an alternative atomic force microscope (AFM) probe-based coupling technique for optical output.
• Measurement of LRSPW attenuation along metal stripes on a dielectric membrane.
• Investigation of output scattering from micron-sized particles.

Main Results:

• The AFM probe technique significantly improved the quality of attenuation measurements, with goodness-of-fit values of 0.93 and 0.99.
• Measured attenuations using the AFM probe method showed excellent agreement with theoretical values, with errors of 6.01% and 0.27%.
• The experimental setup demonstrated good stability (0.01 dB peak to peak over minutes).

Conclusions:

• The proposed AFM probe technique provides a simpler and more effective method for optical probing and coupling to LRSPW.
• This technique offers superior measurement quality compared to traditional prism-based methods.
• The approach has potential for application in various surface plasmon and dielectric waveguides.