GHz oscilloscope to monitor µs-fast phenomena with single-pulse THz spectroscopy

点击翻译按钮获取中文摘要

Slow-motion movies are not only fascinating to watch, they also allow us to understand intricate details of fast and complex phenomena. If the images in each frame are replaced by terahertz (THz) electromagnetic waves, such movies can reveal a large range of low-energy resonances that help us to better understand inner mechanisms of structural, chemical or biological processes. The THz band, located in the deep infrared region of the electromagnetic spectrum, has been increasingly used to identify molecules from their low-energy vibrational modes. The requested GHz oscilloscope is a critical instrument to implement a single-pulse THz characterization system able to trace molecular resonances on the hard-to-access µs time scale. The experimental concept is based on a dispersive Fourier transform technique in which optical pulses, dispersed in a km-long fiber and detected with a fast photodiode, are analyzed by the requested GHz oscilloscope to extract their individual spectral intensity. A single-pulse THz spectrometer is formed when this technique is combined with a nonlinear effect encoding a THz waveform onto the spectral components of a chirped near-infrared pulse. Such a system can monitor unique phenomena featuring fast and non-reproducible dynamics with a sensitivity and resolution ultimately limited by the performance of the oscilloscope. Most specifically, the requested GHz oscilloscope will allow Dr. Ménard to be the first to explore a range of intriguing µs processes in biological systems, such as the THz dynamics of enzyme catalytic cycles. Advances in this field could lead to revolutionary applications such as biocatalytic syntheses of fine chemicals and pharmaceuticals, treatment of metabolic disorders, and bioremediation of contaminated water and soil. Recently, the single-pulse THz spectrometer has already been successively demonstrated in the applicant's lab with a loaned GHz oscilloscope, allowing THz spectroscopy to be performed at unprecedented rates. A manuscript summarizing this work is under review. Timely acquisition of the GHz oscilloscope is crucial to pursue this research program while continuing to gain momentum and seize new opportunities. The cost of renting a similar GHz oscilloscope ($55,000/year) is not economical nor sustainable. Single-pulse experiments require months of work, and the equipment is needed on a full-time basis, especially to complete projects with the highest impact. As such, the requested GHz oscilloscope is essential for the continuation of the applicant's single-pulse THz research program at uOttawa; Without the ability to perform dispersive Fourier transform spectroscopy with this unit, his single-pulse THz program cannot continue. The requested GHz oscilloscope will be used in every single-pulse experiments (>80 hours/month) and will play a central role in the training of HQP in THz photonics and material physics. This instrument will be routinely used by all students.