Large-Scale THz Active Arrays in Silicon for Bio-Chemical Sensing
In this talk, we present new opportunities and challenges for THz sensing through on-chip circuits and microsystems. In particular, chip-scale interactions between electromagnetic
radiations and various types of particles provide new modalities for integrated sensors in bio-chemical applications. First, we focus on polar gas molecule detection/identification through rotational spectroscopy in the low-THz range. Traditionally, there is a severe tradeoff between the requirement for wide-detection range (hence broadband coverage) and the requirement for absolute detection specificity (sub-MHz scanning resolution due to the ultra-narrow spectral linewidth (Q=10 5 ~10 6 )). This leads to large performance degradation in detection speed, sensitivity and efficiency. To address this issue, we present a CMOS spectrometer based on a dual-frequency- comb architecture. By introducing high-parallelism and simultaneous transmit/receive operations, the chip seamlessly covers a 220-to- 320GHz band while increasing the scanning speed by >20x. With its high radiated power of 5.2 mW and sensitivity (NF=15~20 dB), the chip demonstrates ppm-level (3 ppm for HCN) sensitivity for un-concentrated gas samples. In the second part of this talk, we show an effort for the generation of highly-focused radiation wave at 1THz, which could be used in not only vibrational mode spectroscopy of bio-molecules (hydrogen bond in particular), but also high resolution imaging. In particular, we introduce a new scalable array of compact, multi-functional units, which enables the integration of 91 coherent radiators inside only 1mm 2 chip area. Using 130-nm SiGe technology, it generates a
total radiated power of ~0.1mW and an effective isotropically radiated power (EIRP) of 20mW, which improves the prior silicon works at mid-THz band by 10x and 200x, respectively.