Microlensless Interdigitated Photoconductive Terahertz Emitters

TL;DR

This paper introduces a novel interdigitated photoconductive antenna design that eliminates the need for microlens focusing, enabling larger excitation areas and doubling THz emission power compared to traditional designs.

Contribution

The paper presents a new plasmonic interdigitated PCA design that works without microlens arrays, increasing emission power and reducing fabrication costs.

Findings

THz emission power is approximately doubled at 200 mW optical excitation.

Design allows larger excitation area, reducing saturation effects.

Eliminates need for microlens focusing in THz emitters.

Abstract

We report here fabrication of interdigitated photoconductive antenna (iPCA) terahertz (THz) emitters based on plasmonic electrode design. Novel design of this iPCA enables it to work without microlens array focusing, which is otherwise required for photo excitation of selective photoconductive regions to avoid the destructive interference of emitted THz radiation from oppositely biased regions. Benefit of iPCA over single active region PCA is that photo excitation can be done at larger area, hence avoiding the saturation effected at higher optical excitation density. The emitted THz radiation power from plasmonic-iPCAs is ~ 2 times more than the single active region plasmonic PCA at 200 mW optical excitation, which will further increase at higher optical powers. This design is expected to reduce fabrication cost of photoconductive THz sources and detectors.