Design and simulation of terahertz DOE beam shaper using GS algorithm for uniform illumination on HEB mixer arrays

The Development of superconducting Hot Electron Bolometer (HEB) mixer array technology overcomes the efficiency bottleneck of single-pixel scanning through multi-pixel parallel detection, which is essential for achieving highresolution real-time detection and high-throughput spectral analysis. Current quasi-optical methods for coupling RF and local oscillator signals into HEB arrays include fly’s-eye configurations employing silicon lens arrays and single large silicon lens approaches. However, neither solution can simultaneously deliver optimal uniformity and high filling factor. To address this limitation, we propose a 1 THz diffractive optical element (DOE) designed via the Gerchberg-Saxton algorithm that transforms an input Gaussian beam with 1 cm waist radius into a 0.8 cm radius circular flat-top beam with >99% uniformity. Zemax far-field simulations of the computed phase profile yielded results agreeing closely with theoretical predictions. This demonstrates the efficacy of this method in designing DOEs that simultaneously satisfy the dual requirements of uniform illumination and high filling factor for HEB arrays.