Cascaded Raman and Intermodal Four-Wave Mixing in Conventional Non-Zero Dispersion-Shifted Fiber for Versatile Ultra-Broadband Continuum Generation
TL;DR: In this article, the authors demonstrate an efficient ultra-broadband supercontinuum generation in telecom-grade optical fiber by pumping Q-switched subnanosecond laser pulses (0.77ns) at 1064 nm in the normal dispersion region of the fiber.
Abstract: We demonstrate an efficient ultra-broadband supercontinuum generation in telecom-grade optical fiber by pumping Q-switched subnanosecond laser pulses (0.77 ns) at 1064 nm in the normal dispersion region of the fiber. The fiber supports several spatial modes at this pump wavelength. Multiple sidebands with six Raman stokes spanning over more than 1100 nm (starting well below 600 nm and extending beyond 1700 nm) are generated using very low input pump power (average 57 mW). Theoretical analysis shows that cascaded Raman and cascaded intermodal four-wave mixing processes can account for the generation of multiple sidebands. We also demonstrate that the modal composition of the input pump profile can provide an extra degree of freedom in tailoring the multiple Raman peaks in the output spectrum.
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TL;DR: The experimental results show that cascaded four wave mixing (FWM) and passive modulation of pump light can explain the appearance of visible components and pulse performance in time domain respectively.
Abstract: Supercontinuum (SC) generation directly from a random fiber laser (RFL) structure is limited in spectrum span and output power so far. Investigations on wavelength range improvement of SC generated in RFL are analyzed and discussed. The experimental results show that cascaded four wave mixing (FWM) and passive modulation of pump light can explain the appearance of visible components and pulse performance in time domain respectively. To the best of our knowledge, it is the first time a SC covering visible and near-infrared range with 20-dB bandwidth of more than 660 nm is generated directly from a RFL with average output power of 3.4 W, and the spectrum spanning from 600 nm to 1700nm. This work proves that a RFL can be a novel visible to near-infrared SC generation method which has a great potential in various applications.
17 citations
TL;DR: In this paper, the authors address intermodal coupling based nonlinear phenomena in short and long pulse regimes and provide a roadmap for future research directions in the area of multimode nonlinear fiber optics.
9 citations
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TL;DR: In this article, the authors investigate the evolution of coherence property of noise-seeded Stokes wave in short ( 1 ps) regimes and show that the phase synchronization occurs by the transition of the Stokes Wave from incoherent to coherent spectra.
Abstract: We investigate the evolution of coherence property of noise-seeded Stokes wave in short ( 1 ps) regimes. Nonlinear equations describing the evolution of pump and Stokes waves are solved numerically for both the regions. Our statistical analysis explore the hidden coherence characteristics of Stokes wave in long pulse regime. Numerical results proclaim that noise-seeded stimulated Raman process, which plays the role in degradation of coherence in short pulse region, exhibits strong phase synchronization in long pulse regime. The manifestation of phase synchronization occurs by the transition of the Stokes wave from incoherent to coherent spectra. Finally, experiment is performed to validate our numerical results where sub-nanosecond pump is launched in the normal dispersion region of a commercially available fiber. Cascaded Raman based broadband spectrum is generated and exhibits high spectral coherence which is measured through f -2f interferometry.
2 citations
01 Aug 2019
TL;DR: In this paper, a high-power broadband linearly-polarized supercontinuum (LP-SC) laser source was demonstrated by coupling the output of a polarization-maintaining picosecond master oscillator power amplifier (PM-MOPA) at 1064 nm into a few-mode photonic crystal fiber.
Abstract: We demonstrate a high-power broadband linearly-polarized supercontinuum (LP-SC) laser source by coupling the output of a polarization-maintaining picosecond master oscillator power amplifier (PM-MOPA) at 1064 nm into a few-mode polarization-maintaining photonic crystal fiber (PM-PCF). The PM-MOPA delivers 150 ps pulses at a high repetition rate of 80 MHz with 120.4 W average output power. The short wavelength band of LP-SC is extended from 580 nm to 480 nm with the aid of intermodal four wave mixing (FWM). The spectrum is finally broadened to 480 -2400 nm with a maximum average power of 77.4 W. To our knowledge, this is the first demonstration of such a high average power LP-SC generated from PM-PCF with a wide spectrum.
1 citations
TL;DR: Wavelength-dependent transverse modes propagating in the SMF participating in the IMFWM process dramatically expand the spectral range in the visible region, and the experimental results are basically consistent with the theoretical simulations of broadband SC generated in theSMF through the IMF WM process.
Abstract: The compact, high-power, broadband continuum sources are extremely needed for developing portable instruments for various applications such as optical coherence tomography, high-resolution spectroscopy, and so on. Here, we develop a compact high-power, ultra-broadband supercontinuum (SC) light source in a single-mode fiber (SMF) pumped with a Yb:YAG/Cr4+:YAG passively Q-switched microchip laser oscillating at 1030 nm. The spectral bandwidth of the SC light is over 1150 nm covering from 600 to 1750 nm. The maximum average output power is 181.8 mW at an input pump power of 880 mW. The optical efficiency is 20.6%, and the net conversion efficiency is as high as 51.6% with respect to the pump power coupled into the fiber. The ultra-broadband spectrum of the SC generated in the SMF is caused by the intermodal four-wave mixing (IMFWM) and cascade stimulated Raman scattering effects. Various transverse modes have been experimentally observed in SC beam generated in the SMF. Wavelength-dependent transverse modes propagating in the SMF participating in the IMFWM process dramatically expand the spectral range in the visible region. The experimental results are basically consistent with the theoretical simulations of broadband SC generated in the SMF through the IMFWM process.
1 citations
References
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TL;DR: The carrier-envelope phase of the pulses emitted by a femtosecond mode-locked laser is stabilized by using the powerful tools of frequency-domain laser stabilization to perform absolute optical frequency measurements that were directly referenced to a stable microwave clock.
Abstract: We stabilized the carrier-envelope phase of the pulses emitted by a femtosecond mode-locked laser by using the powerful tools of frequency-domain laser stabilization. We confirmed control of the pulse-to-pulse carrier-envelope phase using temporal cross correlation. This phase stabilization locks the absolute frequencies emitted by the laser, which we used to perform absolute optical frequency measurements that were directly referenced to a stable microwave clock.
2,499 citations
"Cascaded Raman and Intermodal Four-..." refers background in this paper
...eas such as in high-precision frequency metrology [2], optical coherence tomography [3], molecular spectroscopy [4] etc....
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TL;DR: Ultrahigh-resolution optical coherence tomography (OCT) using continuum generation in an air-silica microstructure fiber as a low-coherence light source and imaging in biological tissue in vivo was demonstrated.
Abstract: We demonstrate ultrahigh-resolution optical coherence tomography (OCT) using continuum generation in an air–silica microstructure fiber as a low-coherence light source. A broadband OCT system was developed and imaging was performed with a bandwidth of 370 nm at a 1.3‐μm center wavelength. Longitudinal resolutions of 2.5 μm in air and ∼2 μm in tissue were achieved. Ultrahigh-resolution imaging in biological tissuein vivo was demonstrated.
956 citations
"Cascaded Raman and Intermodal Four-..." refers background in this paper
...eas such as in high-precision frequency metrology [2], optical coherence tomography [3], molecular spectroscopy [4] etc....
[...]
TL;DR: In this article, four-photon stimulated scattering has been observed in borosilicate glass under high-power 5300-AA{} picosecond-pulse excitation.
Abstract: Four-photon stimulated scattering has been observed in borosilicate glass under high-power 5300-\AA{} picosecond-pulse excitation. Parametric emission is generated from 4000 to 7000 \AA{} from filaments formed in the glass, the wavelength depending on the emission angle.
759 citations
"Cascaded Raman and Intermodal Four-..." refers background in this paper
...O PTICAL Supercontinuum (SC) is the synergy of several nonlinear processes in which a narrow-band pulse suffers huge spectral broadening and was first observed by Alfano and Shapiro in 1970 [1]....
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TL;DR: In this article, a glass fiber optical waveguide was used for the construction of wide-band fiber amplifiers and Raman oscillators tunable over a range of 100 A. Even though the Raman cross section is quite small, relatively low threshold for Raman emission can be achieved because high optical power densities are maintained over long lengths of waveguide.
Abstract: Stimulated Raman emission in the visible has been observed in glass‐fiber optical waveguides. Even though the Raman cross section is quite small, relatively low threshold for Raman emission can be achieved because high optical power densities are maintained over long lengths of waveguide. The broad stimulated gain bandwidths available in glass should permit the construction of wide‐band fiber amplifiers and Raman oscillators tunable over a range of 100 A.
412 citations
TL;DR: In this article, highly nonlinear ultrashort pulse propagation in the anomalous-dispersion regime of a graded-index multimode optical fiber was investigated and the results indicated that multimode fibres present unique opportunities for observing new spatiotemporal dynamics and phenomena.
Abstract: Highly nonlinear effects are observed in graded-index multimode optical fibres. Multimode fibres are of interest for next-generation telecommunications systems and the construction of high-energy fibre lasers. However, relatively little work has explored nonlinear pulse propagation in multimode fibres. Here, we consider highly nonlinear ultrashort pulse propagation in the anomalous-dispersion regime of a graded-index multimode fibre. Low modal dispersion and strong nonlinear coupling between the fibre's many spatial modes result in interesting behaviour. We observe spatiotemporal effects reminiscent of nonlinear optics in bulk media—self-focusing and multiple filamentation1,2—at a fraction of the usual power. By adjusting the spatial initial conditions, we generate on-demand, megawatt, ultrashort pulses tunable between 1,550 and 2,200 nm; dispersive waves over one octave; intense combs of visible light; and a multi-octave-spanning supercontinuum. Our results indicate that multimode fibres present unique opportunities for observing new spatiotemporal dynamics and phenomena. They also enable the realization of a new type of tunable, broadband fibre source that could be useful for many applications.
327 citations