From chemical analysis to food inspection, optical spectrometers are an indispensable tool in almost all scientific and industrial research fields. However, conventional spectrometers are bulky and costly, which prevents their applications on a mass basis. Researchers all over the world have been struggling to find practical solutions to miniaturize them without sacrificing performance.
Prof. Zongyin Yang of Zhejiang University is dedicated to miniaturizing spectroscopic light sources and detectors. He proposed a new paradigm for the miniaturization of spectrometers, where light dispersion and detection are carried out in an individual nanomaterial structure, representing a platform unmatched in both simplicity and its compact design.
For Yang, the idea of "developing a graphene-nanowire based spectrometer" emerged during his Ph.D. at Cambridge University. This was eventually proven to be an exceedingly challenging and multifaceted problem, requiring high precision device fabrication, complex algorithm development, and an exceptionally robust characterization and measurement system.
After hundreds of failures, Yang finally made a breakthrough – proposing two novel methods to synthesize bandgap-graded semiconductor materials: the source-moving and substrate-moving synthesis. Based on this, he developed a series of theories, methods, and techniques that make use of synthesized bandgap-graded semiconductor materials, leading to a suitable technical direction for the miniaturization of spectrometers.
In 2019, Yang demonstrated the world's smallest spectrometer based on the proposed principles. He replaced dispersive and collimating elements such as prisms and mirrors with nanowire. The active element of the spectrometer, where light is both detected and spectrally resolved, is scaled down to a single compositionally graded nanowire, just hundreds of nanometers in diameter and tens of micrometers long. This is smaller than the diameter of human hair.
In addition to the innovation in the field of spectroscopic detection, Yang has proposed the use of bandgap-graded semiconductor materials as variable laser gain and demonstrated the world's widest wavelength-tunable nanolasers.
In September 2020, Yang joined Zhejiang University as a professor. His main research direction is to continue to promote the scale, commercialization, and industrialization of micro-spectrometer technology. He has led the team to solve the size and cost issues, and then will focus on improving the resolution and sensitivity to further expand its application prospects.