Enhanced Second Harmonic Generation Efficiency via Wavefront Shaping

Thompson, Jonathan V.; Hokr, Brett H.; Throckmorton, Graham A.; Wang, Dawei; Scully, Marlan O.; Yakovlev, Vladislav V.

doi:10.1021/acsphotonics.7b00379

Cited by 18 publications

(12 citation statements)

References 47 publications

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“…Further work will include explorations of the theoretical foundations of spatial effects in high-order nonlinear optical interactions, which we initiated in (11 ). We also plan thorough investigations of algorithmic shaping in the IR.…”

Section: Discussionmentioning

confidence: 99%

Controlled supercontinua via spatial beam shaping

Zhdanova

Shen

Thompson

et al. 2017

Journal of Modern Optics

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Recently, optimization techniques have had a significant impact in a variety of fields, leading to a higher signal-to-noise and more streamlined techniques. We consider the possibility for using programmable phase-only spatial optimization of the pump beam to influence the supercontinuum generation process. Preliminary results show that significant broadening and rough control of the supercontinuum spectrum are possible without loss of input energy. This serves as a proof-of-concept demonstration that spatial effects can controllably influence the supercontinuum spectrum, leading to possibilities for utilizing supercontinuum power more efficiently and achieving arbitrary spectral control.

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Section: Discussionmentioning

confidence: 99%

Controlled supercontinua via spatial beam shaping

Zhdanova

Shen

Thompson

et al. 2017

Journal of Modern Optics

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“…We decompose the complex amplitude into amplitude and phase, and consider the nonlinear polarization of the SHG process [15,18] ( )= ( ) exp[ ( )]…”

Section: Supplementary Materials 1 Theoretical Model Of Shgmentioning

confidence: 99%

“…In this report, we offer a nascent solution to this long-standing problem by utilizing the properties of the second-harmonic (SH) signal [15], which inherits the spatial phase of the incoming wavefront [16][17][18]. The wavefront change induced by the sample modifies the SH signal produced in a nonlinear crystal [18], which can then be used to retrieve the original phase image by solving the inverse problem of the second harmonic generation (SHG). A key advantage of using SH imaging contrast is the capability to encode abundant phase information from the fundamental beam, including the second derivative of phase.…”

Section: Introductionmentioning

confidence: 99%

Second Harmonic Imaging Enhanced by Deep Learning Decipher

et al. 2021

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Wavefront sensing and reconstruction are widely used for adaptive optics, aberration correction, and high-resolution optical phase imaging. Traditionally, interference and/or microlens arrays are used to convert the optical phase into intensity variation. Direct imaging of distorted wavefront usually results in complicated phase retrieval with low contrast and low sensitivity. Here, a novel approach has been developed and experimentally demonstrated based on the phase-sensitive information encoded into second harmonic signals, which are intrinsically sensitive to wavefront modulations. By designing and implementing a deep neural network, we demonstrate the second harmonic imaging enhanced by deep learning decipher (SHIELD) for efficient and resilient phase retrieval. Inheriting the advantages of two-photon microscopy, SHIELD demonstrates single-shot, reference-free, and video-rate phase imaging with sensitivity better than 𝜆 100 and high robustness against noises, facilitating numerous applications from biological imaging to wavefront sensing.

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“…Recently, wavefront shaping [15], [16] and related techniques including transmission matrix measurements, etc. References [17]- [20] have emerged as a promising technique to provide an alternative for imaging through a turbid medium and focusing light in turbid media using linear [21] or nonlinear optical techniques [22], [23]. By increasing constructive interference in a turbid sample, wavefront shaping refocuses light onto a single small spot to enhance the incident energy on the target.…”

Section: Early Optical Probes Based On Fiber Optics For Depth-sensitivementioning

confidence: 99%

Improving Depth Sensitive Fluorescence Spectroscopy With Wavefront Shaping by Spectral and Spatial Filtering

2019

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Depth sensitive optical spectroscopy preferentially detects optical spectra from different depths in layered samples, which plays a crucial role in many applications such as the optical diagnosis of epithelial precancer and cancer. In depth sensitive optical measurements, multiple light scattering in tissues significantly degrades the depth sensitivity to a subsurface target layer. To address this issue, feedback based wavefront shaping led by guide stars can be used to refocus light to increase the depth sensitivity to a target layer. However, the lack of intrinsic guide stars in tissues or tissue-like samples often leads to poor enhancement in depth sensitive Raman/fluorescence measurements (∼20% in the past literature) from the target layer due to the contribution from the overlaying non-target layer. In this study, we demonstrate that spatial filtering and spectral filtering can significantly improve the performance of depth sensitive fluorescence spectroscopy assisted by feedback based wavefront shaping in tissue-like scattering phantoms. The two filtering techniques work by effectively increasing the relative contribution from the target layer to the feedback signal during wavefront optimization through spatially and spectrally rejecting off-target fluorescence light, which is essentially similar to the role of time or coherence gating. When the filtering techniques are applied, a maximum of three-fold enhancement in fluorescence contribution from the target layer is observed, which is in contrast to nearly no enhancement in case of no filtering. This significant enhancement has not been reported previously for depth sensitive optical spectroscopy in the area of feedback based wavefront shaping. Therefore, our work represents a new advance towards the application of wavefront shaping in depth resolved optical spectroscopy for the characterization of layered structures such as epithelial tissues or drug tablets, in which the creation of an external guide star is challenging or not allowed.INDEX TERMS Depth sensitive fluorescence spectroscopy, spatial filtering, spectral filtering, feedback based wavefront shaping.

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Enhanced Second Harmonic Generation Efficiency via Wavefront Shaping

Cited by 18 publications

References 47 publications

Controlled supercontinua via spatial beam shaping

Controlled supercontinua via spatial beam shaping

Second Harmonic Imaging Enhanced by Deep Learning Decipher

Improving Depth Sensitive Fluorescence Spectroscopy With Wavefront Shaping by Spectral and Spatial Filtering

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