Broadband Coherent Anti-Stokes Raman Scattering Spectroscopy Using Pulse-Shaper-Controlled Variable-Wavelength Soliton Pulses from a Photonic Crystal Fiber
TL;DR: In this article, fundamental soliton pulses from a photonic crystal fiber (PCF) were used as variable-wavelength optical pulses in coherent anti-Stokes Raman scattering (CARS) spectroscopy using a single unamplified laser oscillator in a microscopy setup.
Abstract: Fundamental soliton pulses from a photonic crystal fiber (PCF) were used as variable-wavelength optical pulses in coherent anti-Stokes Raman scattering (CARS) spectroscopy using a single un-amplified laser oscillator in a microscopy setup. Both the center wavelengths and the delay times of soliton pulses were controlled simultaneously by shaping the input pulse of a PCF by the use of a pulse shaper and these parameters were switched automatically in measurement. Broadband CARS signals between 500 and 3100 cm-1 of polymer samples have been measured and the most of the Raman peaks in this frequency range of samples were observed clearly by this method.
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TL;DR: Pulse trains of fundamental soliton pulses with different center wavelengths and delay times from a photonic crystal fiber were generated and used as Stokes optical pulses in coherent anti-Stokes Raman scattering (CARS) spectroscopy as mentioned in this paper.
15 citations
TL;DR: In this paper, a single-beam coherent anti-Stokes Raman scattering (CARS) spectroscopy using the combination of a pulse shaper and a photonic crystal fiber (PCF) was demonstrated.
Abstract: Novel single-beam coherent anti-Stokes Raman scattering (CARS) spectroscopy using the combination of a pulse shaper and a photonic crystal fiber (PCF) was demonstrated successfully, where a fundamental soliton Stokes pulse and a spectrally compressed pump pulse were generated in the same PCF. Unlike previous single-beam CARS setups, it can probe C–H stretching vibrations from 2800 to 3100 cm-1 and the resonant Raman C–H stretching vibrations of polystyrene were successfully observed with the single-beam CARS technique.
7 citations
TL;DR: In this paper, the authors report about preparation technique and characterization of structured fibers composed of HMO core glasses and silica cladding, which have been characterized by dilatometrical methods to find T g values of 827-875°C and expansion coefficients between 4.3 and 7.0×10 -6 K -1.
Abstract: We report about preparation technique and characterization of structured fibers composed of HMO core glasses and
silica cladding. Two processes as material preparation techniques have been developed based on glasses prepared by
melting of SAL (e.g. 70SiO 2 -20Al 2 O 3 -10La 2 O 3 ) glasses and the reactive powder sintering (REPUSIL) method. The
melted glasses have been characterized by dilatometrical methods to find T g values of 827-875°C and expansion
coefficients between 4.3 and 7.0×10 -6 K -1 . The latter is one order of magnitude higher than the expansion coefficient of
pure silica glass. Structured fibers (SAL core, silica cladding) were fabricated following the Rod-in-Tube (RIT) and
Granulate-in-Tube (GIT) process. The HMO glasses were chosen due du their high lanthanum content and the expected
high nonlinearity, suitable for nonlinear applications (e.g. supercontinuum sources).
The partial substitution of lanthanum by other rare earth elements (e.g. Ytterbium) allows the preparation of fibers with
extremely high rare earth concentration up to 5 mol% Yb 2 O 3 . The concentration of alumina in the HMO glasses as
"solubilizer" for lanthanide was adjusted to about 20 mol%. So we overcame the concentration limits of rare earth
doping of MCVD (maximum ca. 2 mol% RE 2 O 3 ). Nevertheless, the investigated HMO glasses show their limits by
integration in structured silica based fibers: Optical losses are typically in the dB/m range, best value of this work is
about 600 dB/km.
The mechanical stability of fibers is influenced by mechanical strain caused by the high thermal expansion of the core
material and the lower network bonding stability of the HMO glasses, but partially compensated by the silica cladding.
6 citations
Cites background from "Broadband Coherent Anti-Stokes Rama..."
...In recent years great attention has been paid to nonlinear fiber applications like supercontinuum generation [1 – 3], Raman amplification [4, 5], Brillouin laser systems [6, 7] and parametric amplification [8]....
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30 Mar 2012
TL;DR: In this paper, a photonic crystal fiber (PCF) is used to generate ultrabroadband optical pulses by propagating femtosecond optical pulses in these fibers, and the properties of the fundamental solitons from a PCF and its applications studied in our laboratory.
Abstract: A photonic crystal fiber (PCF) is a fiber that contains the regular (usually hexagonal) arrays of air holes in the propagation direction of an optical fiber. At the center position, the core is created by not making an air hole and the light wave propagates at the core position since the effective refractive index of the core is higher than that of the photonic crystal clad surrounding the core. Photonic crystal fibers of this type have been used to generate ultrabroadband optical pulses by propagating femtosecond optical pulses in these fibers (Ranka et al., 2000). The core diameter of a PCF for the generation of ultrabroadband optical pulses using a Ti:sapphire laser (center wavelength ∼800 nm) is about 1-2 μm if it is assumed that the silica core is surrounded by regular air holes. Due to the waveguide dispersion, the group velocity dispersion (GVD) becomes negative at 800 nm. Because of the small core diameter and the negative GVD, nonlinear effects are enhanced and optical solitons are generated in a PCF. Theoretical calculations for elucidating the mechanism of the ultrabroadband pulse generation in a PCF have been performed (Husakou & Herrmann, 2001) and the generation of fundamental soliton pulses by the fission of an input higher-order soliton pulse due to the third and higher order dispersion as well as the higher-order nonlinear effects including the Raman effects are found to be important for the spectral broadening. Supercontinuum generation in a PCF is reviewed in (Dudley et al., 2006). The center wavelength of the generated fundamental soliton pulse becomes longer as it propagates in a PCF due to soliton self-frequency shift and its center wavelength can be changed by the peak power or the chirp of an input pulse. Recently, it was used as a variable-wavelength light source in various applications including coherent anti-Stokes Raman scattering (CARS) spectroscopy and optical coherence tomography (OCT). The present article describes the properties of the fundamental solitons from a PCF and its applications studied in our laboratory.
4 citations
Cites methods from "Broadband Coherent Anti-Stokes Rama..."
...We have studied the control of the soliton center wavelengths by the chirp of an input pulse (Karasawa et al., 2007; Tada & Karasawa, 2008)....
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16 May 2010
TL;DR: In this paper, a quasi-supercontinuum light source in the wavelength range from 0.85 to 1.1 micrometer generated from a photonic crystal fiber was used for coherent anti-Stokes Raman scattering spectroscopy.
Abstract: Broadband coherent anti-Stokes Raman scattering spectroscopy was performed successfully for the first time using a quasi-supercontinuum light source in the wavelength range from 0.85 to 1.1 micrometer generated from a photonic crystal fiber.
3 citations
Cites methods from "Broadband Coherent Anti-Stokes Rama..."
...The group delay of a soliton pulse changes as its center wavelength changes and we have used a pulse shaping technique for the adjustment of the group delay [3,4]....
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...1 m using a PCF and applied to CARS spectroscopy for the first time in our knowledge, where the power modulation was performed by an AOM and the group delay adjustment was performed by placing a pair of prisms after the PCF, since it was found that the group delay of soliton pulses depended on wavelength approximately linearly [3]....
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References
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TL;DR: The theory of Raman effects, which causes a continuous downshift of the mean frequency of pulses propagating in optical fibers, agrees well with recent measurements.
Abstract: Raman effects cause a continuous downshift of the mean frequency of pulses propagating in optical fibers. For solitons in silica fibers, the effect varies roughly with the inverse fourth power of the pulse width. At 1.5-μm wavelength in a fiber with 15 psec/nm/km time-of-flight dispersion, a soliton of 250-fsec duration is predicted to shift by its own spectral width after about 100m of propagation. The theory agrees well with recent measurements.
1,051 citations
TL;DR: Coherent anti-Stokes Raman scattering (CARS) microscopy permits vibrational imaging with high-sensitivity, high speed, and three-dimensional spatial resolution as discussed by the authors, and the development of multiplex CARS microspectroscopy, which allows high-speed characterization of microscopic samples.
Abstract: Coherent anti-Stokes Raman scattering (CARS) microscopy permits vibrational imaging with high-sensitivity, high speed, and three-dimensional spatial resolution. We review recent advances in CARS microscopy, including experimental design, theoretical understanding of contrast mechanisms, and applications to chemical and biological systems. We also review the development of multiplex CARS microspectroscopy, which allows high-speed characterization of microscopic samples, and CARS correlation spectroscopy, which probes fast diffusion dynamics with vibrational selectivity.
921 citations
TL;DR: A truly broadband CARS imaging instrument is demonstrated that is used to acquire hyperspectral images with vibrational spectra over a bandwidth of 2500 cm (-1) with a resolution of 13 cm(-1).
Abstract: Coherent anti-Stokes Raman scattering (CARS) microscopy is emerging as a powerful method for imaging materials and biological systems, partly because of its noninvasiveness and selective chemical sensitivity. However, its full potential for species-selective imaging is limited by a restricted spectral bandwidth. Recent increases in bandwidth are promising but still are not sufficient for the level of robust component discrimination that would be needed in a chemically complex milieu found, for example, in intracellular and extracellular environments. We demonstrate a truly broadband CARS imaging instrument that we use to acquire hyperspectral images with vibrational spectra over a bandwidth of 2500 cm(-1) with a resolution of 13 cm(-1).
298 citations
TL;DR: Results show that CARS microscopy has the potential to become an important complementary technique that can be used with other well-established microscopic methods, and it can be expected that the impressive growth of the field will continue.
Abstract: Coherent anti-Stokes Raman scattering (CARS) microscopy is presented as a new nonlinear optical technique. The combination of vibrational spectroscopy and microscopy allows highly sensitive investigations of unlabelled samples. CARS is an ideal tool for studying a broad variety of samples. The main drawback of the technique is its non-zero-background nature, which implies that the signal has to be detected against a nonresonant background. The need to solve this problem is reflected in the rapid technological developments that have been observed during the last decade. Recent results show that CARS microscopy has the potential to become an important complementary technique that can be used with other well-established microscopic methods. Although it has some limitations, it offers unique access to many problems that cannot be tackled with conventional techniques. For this reason, it can be expected that the impressive growth of the field will continue.
279 citations
01 Jul 2003
TL;DR: In this paper, a coherent anti-Stokes Raman scattering (CARS) microscopy was demonstrated using a light source consisting of the output from a photonic crystal fiber pumped by a standard Ti:sapphire oscillator and the fundamental oscillator beam.
Abstract: Coherent anti-Stokes Raman scattering (CARS) microscopy is demonstrated using a light source consisting of the output from a photonic crystal fiber pumped by a standard Ti:sapphire oscillator and the fundamental oscillator beam.
266 citations