Advanced optical terahertz fingerprint sensor based on coherent perfect absorption.

Area of Science:

• Optoelectronics and Photonics
• Terahertz (THz) Sensing Technology
• Materials Science

Background:

• Terahertz (THz) spectroscopy is valuable for material identification but requires highly sensitive sensors.
• Coherent Perfect Absorption (CPA) offers a mechanism for enhanced light-matter interaction.
• Magneto-optical effects in materials like Indium Antimonide (InSb) can be leveraged for optical control.

Purpose of the Study:

• To propose and theoretically analyze an advanced optical THz fingerprint sensor.
• To utilize the magneto-optical effect for exciting CPA in a photonic structure.
• To demonstrate the sensor's capability for qualitative and quantitative analysis of materials like alpha-lactose.

Main Methods:

• Design of a one-dimensional layered photonic structure with a cavity for THz fingerprint measurement.
• Excitation of CPA using the magneto-optical effect of magnetized InSb.
• Numerical simulation integrating a Drude-Lorentz model and the Transfer Matrix Method (TMM).

Main Results:

• Theoretical calculation of key performance metrics: sensitivity (S), linear range (LR), quality factor (Q), figure of merit (FOM*), and detection limit (DL).
• Achieved high sensitivity (S = 0.78255 μm⁻¹), average Q = 8019.2, average FOM* = 13234.4 (THz μm)⁻¹, and a low DL = 4.21 × 10⁻⁶.
• Demonstrated feasibility for analyzing alpha-lactose thickness from 0-0.5 μm using amplitude modulation detection.

Conclusions:

• The proposed THz fingerprint sensor based on CPA exhibits excellent performance characteristics.
• The study provides a theoretical framework and simulation results for fabricating advanced THz sensors.
• Consideration of disorder effects is crucial for practical sensor fabrication and performance.