Low-cost ultra-thin broadband terahertz beam-splitter

• Published in: Optics express Vol. 20; no. 5; pp. 4968 - 4978
• Main Authors: Ung, Benjamin S-Y, Fumeaux, Christophe, Lin, Hungyen, Fischer, Bernd M, Ng, Brian W-H, Abbott, Derek
• Format: Journal Article
• Language: English
• Published: United States 27-02-2012
• Subjects: Computer-Aided Design; Equipment Design; Equipment Failure Analysis; Interferometry - instrumentation; Refractometry - instrumentation; Terahertz Radiation
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/oe.20.004968

A low-cost terahertz beam-splitter is fabricated using ultra-thin LDPE plastic sheeting coated with a conducting silver layer. The beam splitting ratio is determined as a function of the thickness of the silver layer--thus any required splitting ratio can be printed on demand with a suitable rapid prototyping technology. The low-cost aspect is a consequence of the fact that ultra-thin LDPE sheeting is readily obtainable, known more commonly as domestic plastic wrap or cling wrap. The proposed beam-splitter has numerous advantages over float zone silicon wafers commonly used within the terahertz frequency range. These advantages include low-cost, ease of handling, ultra-thin thickness, and any required beam splitting ratio can be readily fabricated. Furthermore, as the beam-splitter is ultra-thin, it presents low loss and does not suffer from Fabry-Pérot effects. Measurements performed on manufactured prototypes with different splitting ratios demonstrate a good agreement with our theoretical model in both P and S polarizations, exhibiting nearly frequency-independent splitting ratios in the terahertz frequency range.