Development of Wavefront Shaping of Ultrashort Optical Pulses via Digital Optical Phase Conjugation

2019 Fiscal Year Final Research Report

• Project/Area Number: 16K13934
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Physical chemistry
• Research Institution: Kobe University
• Principal Investigator: Kaoru Ohta 神戸大学, 分子フォトサイエンス研究センター, 特命准教授 (30397822)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Keywords: 透過行列 / 散乱体 / 超短パルス光 / 波形制御 / 空間位相変調器

Outline of Final Research Achievements

When a coherent light propagates in scattering media, the scattered light forms a destructive interference pattern, which is known as “speckle”. It was considered that this light scattering was a fundamental obstacle for molecular spectroscopy and optical microscopy. However, it was shown that one can focus the light at a desired target even in scattering media by spatially shaping the wavefront of the incident light. This is based on the fact that the scattering process is linear and deterministic. In this study, we demonstrated the spatio-temporal pulse-shaping technique to control the amplitude and phase of ultrashort pulses both in space and time. For ultrashort pulses, it is important to control not only the wavefront of the pulse but also the spectral phase distortions caused by the transmission of the dispersive media. We used the pulse shaper to manipulate the optical properties of ultrashort pulses in time domain.

Free Research Field

物理化学

Academic Significance and Societal Importance of the Research Achievements

近年、天文学の分野で観測像の歪みを補正する目的で開発された波面補償法が、生体組織深部のイメージングの分野で盛んに行われるようになった。しかし、本研究で対象としているような光の散乱や拡散が起こるような系では全く無力である。本研究課題では、このような困難な状況でも適用できる超短パルス光の波形制御法を開発した。本研究手法を用いることにより、散乱体透過後の超短パルス光を空間上の任意の一点に集光することが可能となる。本手法を、超短パルス光を用いた様々な非線形光学イメージングに応用した場合、散乱の寄与が非常に大きい生体試料などその適用範囲は劇的に拡がるものと考えられる。