High spectro-temporal compression on a nonlinear CMOS-chip

Optical pulses are fundamentally defined by their temporal and spectral properties. The ability to control pulse properties allows practitioners to efficiently leverage them for advanced metrology, high speed optical communications and attosecond science. Here, we report 11× temporal compression of 5.8 ps pulses to 0.55 ps using a low power of 13.3 W. The result is accompanied by a significant increase in the pulse peak power by 9.4×. These results represent the strongest temporal compression demonstrated to date on a complementary metal–oxide–semiconductor (CMOS) chip. In addition, we report the first demonstration of on-chip spectral compression, 3.0× spectral compression of 480 fs pulses, importantly while preserving the pulse energy. The strong compression achieved at low powers harnesses advanced on-chip device design, and the strong nonlinear properties of backend-CMOS compatible ultra-silicon-rich nitride, which possesses absence of two-photon absorption and 500× larger nonlinear parameter than in stoichiometric silicon nitride waveguides. The demonstrated work introduces an important new paradigm for spectro-temporal compression of optical pulses toward turn-key, on-chip integrated systems for all-optical pulse control.

A Multiplexed Chemical Sensing CMOS Imager

A miniaturized and multiplexed chemical sensing technology is urgently needed to empower mobile devices, Internet-of-Things (IoTs) and robots for various new applications. Here, we show that a complementary metal-oxide-semiconductor (CMOS) imager can be turned into a multiplexed colorimetric sensing chip by coating micron-scale colorimetric sensing spots on the imager surface. Each sensing spot contains chemical sensing materials and nanoparticles for colorimetric signal enhancement. The sensitivity is spot-size invariant, and high-performance chemical sensing can be achieved on sensing spot as small as ~ 10 µm. This great scalability combined with millions of pixels of a CMOS imager offers a promising platform for highly integrated chemical sensors. Moreover, the chemical CMOS chip can be readily integrated with mobile electronics. As a proof-of-concept, we have built a smartphone accessary based on this chemical CMOS chip for personal health management. We anticipate that this new platform will pave the way for the widespread application of chemical sensing, such as mobile health (mHealth), IoTs, electronic nose, and smart homes.