Optimizing signal collection efficiency of the VIPA-based Brillouin spectrometer

Zhaokai Meng,Vladislav V. Yakovlev

doi:10.1142/s1793545815500212

Zhaokai Meng, Vladislav V. Yakovlev

Open Access

https://doi.org/10.1142/s1793545815500212

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Abstract

Brillouin spectroscopy is an emerging tool for microscopic optical imaging as it allows for noninvasive and direct assessment of the viscoelastic properties of materials. Recent advances of background-free confocal Brillouin spectrometer allows investigators to acquire the Brillouin spectra for turbid samples as well as transparent ones. However, due to strong signal loss induced by the imperfect optical setup, the Brillouin photons are usually immersed in background noise. In this report, we proposed and experimentally demonstrated multiple approaches to enhance the signal collection efficiency. A signal enhancement by > 4 times can be observed, enabling observation of ultra-weak signals.

Highlights

Brillouin spectroscopy is a powerful technique for material characterization, providing unique information about the viscoelasticity of a substance,[1] and has found wide usage in remote sensing.[2] material science[3,4] and biomedical applications.[5,6,7,8] Brillouin scattering originates from the inelastic interaction between the incident electromagnetic wave and the acoustic phonons within the material
Compared to other imaging techniques that are capable of quantifying material's mechanical properties (e.g., Refs. 9 and 10), Brillouin spectroscopy o®ers a noninvasive and label-free contrast mechanism with microscopic spatial resolution
Typical Brillouin spectrometers are fully based on optics, which makes it easy to couple with other optical imaging techniques (e.g., optical coherent tomography (OCT),[12,13] Raman spectroscopy[14,15,16,17] and optical sensors18,19)

Summary

Introduction

Brillouin spectroscopy is a powerful technique for material characterization, providing unique information about the viscoelasticity of a substance,[1] and has found wide usage in remote sensing.[2] material science[3,4] and biomedical applications.[5,6,7,8] Brillouin scattering originates from the inelastic interaction between the incident electromagnetic wave and the acoustic phonons within the material. The incident optical frequency experiences a shift proportional to the speed of sound in the medium. The medium's elastic modulus, which is directly related with the speed of sound in the medium, can be determined by measuring the Brillouin shift. Compared to other imaging techniques that are capable of quantifying material's mechanical properties The microscopic elasticity of the living organisms enables investigations of cell mechanics, which is essential for understanding biological development and disease pathophysiology.[11] typical Brillouin spectrometers are fully based on optics, which makes it easy to couple with other optical imaging techniques (e.g., optical coherent tomography (OCT),[12,13] Raman spectroscopy[14,15,16,17] and optical sensors[18,19])

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