On-chip integration of laser-ablated zone plates for detection enhancement of InGaAs bow-tie terahertz detectors

• Published in: Electronics letters 2014-09, Vol.50 (19), p.1367-1369
• Main Authors: Minkevičius, L, Tamošiūnas, V, Madeikis, K, Voisiat, B, Kašalynas, I, Valušis, G
• Format: Article
• Language: English
• Subjects: angle measurement; angular measurement; bow–tie‐shaped terahertz detector; detected signal dependence measurement; Detectors; diffractive optical elements; Diffractive optics; direct laser write technique; Direct laser writing; Finite difference method; finite difference time‐domain analysis; finite‐difference time‐domain simulation; frequency 0.76 THz; gallium arsenide; Incident waves; indium compounds; InGaAs; InP; laser ablation; laser‐ablated zone plate; magnitude detection enhancement; Mathematical analysis; measurement by laser beam; Microwave technology; on‐chip integration; optical focusing; optical sensors; secondary diffractive optics; Simulation; size 500 mum; submillimetre wave detectors; terahertz wave detectors; Zone plates
• ISSN: 0013-5194; 1350-911X; 1350-911X
• DOI: 10.1049/el.2014.1893

One order of magnitude detection enhancement of bow-tie-shaped InGaAs-based terahertz detectors by on-chip incorporation of the secondary diffractive optics is reported. Zone plates were produced directly on the bottom surface of 500 µm-thick InP substrate using the direct laser write technique after an array of InGaAs detectors was formed on the front surface of the wafer. Measurements of detected signal dependence on the angle of the incident wave were performed at 0.76 THz and compared with finite-difference time-domain simulation results. Good correlation of the results shows that the observed enhancement is indeed caused by the focusing performance of the zone plate rather than by the exceptional sensitivity of the single detector.