PhD. of Yize Liu

Author: Yize Liu Promotors: Nicolas Le Thomas and Anton Nikiforov, Christopher Leys English Title: On-Chip Integrated UV Microplasma Source for Biophotonic Applications Date: 23/9/2026 Main Language: English ISBN number: 978-94-93570-18-4 Thesis: (30.4MB) Presentation: (5.9MB)

Abstract

A major challenge in life sciences is the lack of compact, efficient ultraviolet (UV) light sources for miniaturized diagnostic devices. UV radiation is highly useful because many biomolecules naturally absorb or fluoresce under it, enabling label-free detection, sterilization, and advanced chemical analysis. However, conventional UV lamps and lasers are bulky, expensive, and incompatible with chip-scale integration.
This PhD research develops a miniature UV source based on a microscale dielectric barrier discharge (microplasma) placed directly on a photonic chip. The plasma emits UV light that couples into the chip’s waveguide via evanescent fields. Using a helium-air mixture, heavy particle reactions (Penning ionization and charge exchange) generate excited emitters at the chip surface, overcoming the plasma sheath. Optimizing the electrode gap and voltage waveform increases surface UV emission by 48%. A theoretical model predicts the plasma-coupled output power to be 2.9–11.5 picowatts.
To verify this, a detection system sensitive to 0.39 picowatt was developed. Direct measurement of the plasma-coupled output was prevented by unavoidable chip contamination from environmental dust. Nevertheless, the underlying coupling principle remains sound. This work paves the way for fully integrated, chip-scale UV light sources for portable biosensing, medical diagnostics, and quantum applications.

Related Research Topics

• Photonic integrated circuits for UV