Thinking Infrared

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Recent Research Highlights

 

My research interests include metamaterials, infrared spectroscopy, and ultrafast x-ray streak camera.  

Infrared Spectroscopy 

 

Infrared refers to the light with wavelength of between a few millimeter and roughly 1 micrometer. Infrared spectroscopy can give frequnecy information of the infrared light after its interaction with matters (reflected or transmitted or generated from them). A prism is a simple spectrometer which tells the frequency components of the incident light. By putting a sample into the light path before it passes the prism, we can observe a change in the frequency components of the output light from the prism due to the absorption of the sample at certain frequencies. We say we get a transmission spectrum of the sample.

 

 

At Infrared Beamline, we use Fourier Transform Infrared Spectrometers (FTIR) to obtain high quality spectra of various forms of materials.


Metamaterials 
Metamaterials are a set of photonic crystals which exhibit a negative index of refraction at the designed frequency range. One of the basic ideas is to build low-loss magnetic resonators with metals. The magnetic resonance induces a negative permeability at the resonance frequency while the electron plasma in metal provides a broadband negative permittivity. Eventually the artificial material will have negative index of refraction if the loss is negligible.




Ultrafast X-Ray Streak Camera
A prism is a good analogy to a streak camera.  The lights with different frequences travel at different speed so that when they travel in a prism, Fermat's principle allows the slower light travel in a shorter distance. So the lights with different speeds are separated into different paths by the prism. A streak camera is going to separate electrons travel at different time delay into different paths so that eventually one can measure the duration of a fast and short electron pulse, by measuring the separating distance between the electrons. When the electron pulses are generated by a ultrashort x-ray pulse, we can then tell the duration of the x-ray pulse by measuring the duration of the electron pulse it generates.