Optical-microwave pump-probe studies of electronic properties in novel materials

TL;DR

This paper develops broadband microwave-optical pump-probe spectrometers to study electronic properties in materials, enabling detailed quantum state and charge dynamics analysis with high sensitivity.

Contribution

It introduces two novel spectrometers using broadband coplanar waveguides for enhanced microwave coupling and sensitivity in optical-microwave pump-probe experiments.

Findings

Successful measurement of ODMR maps on nitrogen-vacancy centers in diamond

Time-resolved photoconductivity in p-doped silicon demonstrated

High sensitivity to minute conductivity changes achieved

Abstract

Combined microwave-optical pump-probe methods are emerging to study the quantum state of spin qubit centers and the charge dynamics in semiconductors. A major hindrance is the limited bandwidth of microwave irradiation/detection circuitry which could be overcome with the use of broadband coplanar waveguides (CPW). We present the development and performance characterization of two spectrometers: an optically detected magnetic resonance spectrometer (ODMR) and a microwave detected photoconductivity measurement. In the first method light serves as detection and microwaves excite the investigated medium, while in the second the roles are interchanged. The performance is demonstrated by measuring ODMR maps on the nitrogen-vacancy center in diamond and time resolved photoconductivity in p-doped silicon. The results demonstrate both an efficient coupling of the microwave irradiation to the samples as well as an excellent sensitivity for minute changes in sample conductivity.