Brighter CARS hypermicroscopy via “spectral surfing” of a Stokes supercontinuum

Porquez, J. G.; Cole, R. A.; Tabarangao, Joel T.; Slepkov, Aaron D.

doi:10.1364/ol.42.002255

Cited by 10 publications

(2 citation statements)

References 26 publications

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“…Users of femtoWHITE CARS modules have, to date, used a pick-off from the fs seed laser as the pump and combined that with just the long wavelength part of the SC as the Stokes, thus losing the energy in the short-wavelength part of the SC and reducing signal power [27,36,37]. We wanted to prevent the waste of that short-wavelength power so, motivated partly by the recently reported technique using intra-pulse frequency combinations for broadband spectrumbased 'hyperspectral' 3-color CARS [13], we have used the full spectrum from an all normal dispersion (ANDi) fiber, NL-1050-NEG-1 from NKT Photonics, to produce a coherent continuum [38] and demonstrated its use for SF-CARS and SHG/SFG imaging.…”

Section: Introductionmentioning

confidence: 99%

Multimodal spectral focusing CARS and SFG microscopy with a tailored coherent continuum from a microstructured fiber

et al. 2020

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We report a technologically novel microscopy system for bioimaging based on a 100 fs titanium:sapphire (Ti:Sa) laser pumped coherent continuum from a tailored, 9-cm long, all normal dispersion (ANDi) fiber, enabling concurrent image contrast with (a) spectral focusing coherent anti-Stokes Raman scattering (SF-CARS) (spanning 900-3200 cm −1) and (b) sum frequency generation (SFG). Both modalities were efficiently excited with power levels at the microscope focus compatible with biological samples. Moreover, using the continuum, images were recorded in the back-scattering (epi-detection) geometry, without the necessity for an expensive, computer-controlled, spatial light modulator (SLM), clearly demonstrating the strong signal levels achieved. Image contrast from the multiple modalities provided greater chemical and structural insights than imaging with any single technique in isolation. Numerical simulations supported these developments in regard to both the optimum fiber length for SC generation and the achievement of high spectral resolution in SF-CARS via careful group delay dispersion matching across the pump and Stokes pulses using just an inexpensive sequence of short glass blocks inserted into the Stokes beam. We show bio-images of mouse tissue recorded concurrently via label/stain-free contrast from multiple modalities: CARS, two-photon auto-fluorescence (TPaF) and second harmonic/sum frequency generation (SHG/ SFG). Overall, our approach delivers optimum performance in back-scattered (epi-) detection configuration, suited for thick samples, at reduced complexity and cost. The addition of this simple fiber add-on to lasers already widely used for TPF microscopy can thus extend the capabilities of a significant number of existing microscopy laboratories.

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Section: Introductionmentioning

confidence: 99%

Multimodal spectral focusing CARS and SFG microscopy with a tailored coherent continuum from a microstructured fiber

et al. 2020

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“…Applications of coherent anti-Stokes Raman scattering (CARS) as a vibrational imaging tool [1,2] are presently subject of intensive investigation, and novel experimental configurations are reported to reduce cost and complexity of the apparatus while improving the system performances to address specific issues. In particular, systems equipped with a single femtosecond laser oscillator in the so-called multiplex CARS configuration have been demonstrated to be very interesting for biomedical applications because of their capability of hyperspectral imaging with energies adequate for interaction with biological samples [3][4][5][6] at reduced costs and complexity.…”

Section: Introductionmentioning

confidence: 99%

Studies of supercontinuum generation in a photonic crystal fiber for use as Stokes beam in a single‐laser femtosecond micro‐CARS setup

Gagliardi

Marrocco

Rondino

et al. 2020

J Raman Spectroscopy

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Photonic crystal fibers (PCFs) have gained popularity thanks to the use of their broad and efficient supercontinuum (SC) emission as Stokes source in ultrafast multiplex coherent anti-Stokes Raman scattering microscopy. Here, the infrared portion of the SC emitted by a widely used PCF is studied in a basic CARS experiment with a single laser oscillator operated at various conditions of power and chirp values. The dependence of the SC and CARS signal of reference cyclohexane sample on the operative conditions of the laser is examined and illustrated by means of statistical approaches that serve the purpose of defining and quantifying the reliability of CARS measurements in relation to the characteristic of the Stokes pulse coming from the fiber. Statistical techniques based on principal component analysis, on calculation of statistical momenta of the SC spectra, and on Allan variance studies are introduced to help to identify the best working regime. Principal component analysis was used to quantify the correlation of SC spectra with PCF input power, which is found to be stronger at high laser beam chirp values. First and second momenta of SC spectra allow identification of best operating conditions with respect to peak emission wavelength and spectral width. Finally, the behavior of Allan variance shows that the time stability of Stokes and CARS signals clearly depends on the chirp of the pump pulse, evidencing that high chirp conditions correspond to lower variance values at the expense of stability for longer measurement times.

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Overview of Supercontinuum Sources for Multiphoton Microscopy and Optical Biopsy

Zhao

Iftimia

2019

Neurophotonics and Biomedical Spectroscopy

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Brighter CARS hypermicroscopy via “spectral surfing” of a Stokes supercontinuum

Cited by 10 publications

References 26 publications

Multimodal spectral focusing CARS and SFG microscopy with a tailored coherent continuum from a microstructured fiber

Multimodal spectral focusing CARS and SFG microscopy with a tailored coherent continuum from a microstructured fiber

Studies of supercontinuum generation in a photonic crystal fiber for use as Stokes beam in a single‐laser femtosecond micro‐CARS setup

Overview of Supercontinuum Sources for Multiphoton Microscopy and Optical Biopsy

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