Extensive Q-factor tuning for leaky modes with minimal frequency variation in asymmetric slab grating structures.

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Leaky modes in optical structures are crucial for various photonic applications.
• Controlling the quality (Q) factor of leaky modes is essential for device performance.
• Asymmetric structures offer unique ways to manipulate light propagation.

Purpose of the Study:

• To investigate an asymmetric slab grating structure for tunable Q-factor control of leaky modes.
• To minimize frequency variations while achieving significant Q-factor tuning.
• To explore the underlying physics of leaky mode behavior in asymmetric gratings.

Main Methods:

• Utilized an asymmetric slab grating structure with a laterally shifted grating.
• Performed simulations to analyze the impact of grating shift on Q-factor and frequency.
• Conducted experimental verification in the terahertz (THz) range.

Main Results:

• Lateral shifting of one grating induced extensive Q-factor changes with minimal frequency variation.
• The band-flip filling fraction remained unaffected by the grating shift.
• Experimental results confirmed significant control over the leaky mode's Q-factor.

Conclusions:

• The asymmetric slab grating structure provides a method for mechanically controllable Q-factor tuning.
• This approach is applicable to the development of tunable filters and sensors.
• The study reveals new insights into leaky modes within asymmetric optical lattices.