From spectral broadening to recompression: dynamics of incoherent optical waves propagating in the fiber

AbstractInterplay between dispersion and nonlinearity in optical fibers is a fundamental research topic of nonlinear fiber optics. Here we numerically and experimentally investigate an incoherent continuous-wave (CW) optical field propagating in the fiber with normal dispersion, and introduce a distinctive spectral evolution that differs from the previous reports with coherent mode-locked fiber lasers and partially coherent Raman fiber lasers [Nat. Photonics 9, 608 (2015).]. We further reveal that the underlying physical mechanism is attributed to a novel interplay between group-velocity dispersion (GVD), self-phase modulation (SPM) and inverse four-wave mixing (IFWM), in which SPM and GVD are responsible for the first spectral broadening, while the following spectral recompression is due to the GVD-assisted IFWM, and the eventual stationary spectrum is owing to the dominant contribution of GVD effect. We believe this work can not only expand the light propagation in the fiber to a more general case and help advance the physical understanding of light propagation with different statistical properties, but also benefit the applications in sensing, telecommunications and fiber lasers.

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Vectorial dispersive shock waves in optical fibers

Communications Physics ◽

10.1038/s42005-019-0241-6 ◽

2019 ◽

Vol 2 (1) ◽

Cited By ~ 6

Author(s):

J. Nuño ◽

C. Finot ◽

G. Xu ◽

G. Millot ◽

M. Erkintalo ◽

...

Keyword(s):

Shock Waves ◽

Fiber Optics ◽

Optical Fibers ◽

Continuous Wave ◽

Blast Waves ◽

Nonlinear Fiber Optics ◽

Nonlinear Phase ◽

Perfect Fluids ◽

Bose Einstein ◽

Wave Phenomena

Abstract Dispersive shock waves are a universal phenomenon encountered in many fields of science, ranging from fluid dynamics, Bose-Einstein condensates and geophysics. It has been established that light behaves as a perfect fluid when propagating in an optical medium exhibiting a weakly self-defocusing nonlinearity. Consequently, this analogy has become attractive for the exploration of dispersive shock wave phenomena. Here, we observe of a novel class of vectorial dispersive shock waves in nonlinear fiber optics. Analogous to blast-waves, identified in inviscid perfect fluids, vectorial dispersive shock waves are triggered by a non-uniform double piston imprinted on a continuous-wave probe via nonlinear cross-phase modulation, produced by an orthogonally-polarized pump pulse. The nonlinear phase potential imparted on the probe results in the formation of an expanding zone of zero intensity surrounded by two repulsive oscillating fronts, which move away from each other with opposite velocities.

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Numerical calculation of the light propagation in tapered optical fibers for optical neural interfaces

10.1101/2021.02.08.430223 ◽

2021 ◽

Author(s):

Rosa Mach-Batlle ◽

Marco Pisanello ◽

Filippo Pisano ◽

Massimo De Vittorio ◽

Ferruccio Pisanello ◽

...

Keyword(s):

Fiber Optics ◽

Mouse Brain ◽

Optical Fibers ◽

Light Propagation ◽

Cylindrical Symmetry ◽

Neural Interfaces ◽

Optical Systems ◽

Computational Technique ◽

Approaches To Study ◽

Beam Envelope

AbstractAs implantable optical systems recently enabled new approaches to study the brain with optical radiations, tapered optical fibers emerged as promising implantable waveguides to deliver and collect light from sub-cortical structures of the mouse brain. They rely on a specific feature of multimodal fiber optics: as the waveguide narrows, the number of guided modes decreases and the radiation can gradually couple with the environment. This happens along a taper segment whose length can be tailored to match with the depth of functional structures of the mouse brain, and can extend for a few millimeters. This anatomical requirement results in optical systems with an active area very long compared to the wavelength of the light they guide and their behaviour is typically estimated by ray tracing simulations, being finite-elements methods computationally too heavy. Here we present a computational technique that exploits the beam-envelope method and the cylindrical symmetry of the fibers to provide an efficient and exact calculation of the electric field along the fibers, which may enable the design of neural interfaces optimized to meet different goals.

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Hole-Assisted Lightguide Fiber - A Practical Derivative of Photonic Crystal Fiber

MRS Proceedings ◽

10.1557/proc-722-l4.2 ◽

2002 ◽

Vol 722 ◽

Cited By ~ 4

Author(s):

Takemi Hasegawa ◽

Eisuke Sasaoka ◽

Masashi Onishi ◽

Masayuki Nishimura ◽

Yasuhide Tsuji ◽

...

Keyword(s):

Optical Properties ◽

Photonic Crystal ◽

Group Velocity ◽

Fiber Optics ◽

Optical Fibers ◽

Velocity Dispersion ◽

Transmission Loss ◽

Photonic Bandgap ◽

Group Velocity Dispersion ◽

Microstructured Fibers

AbstractUsage of air holes in optical fibers has become a hot subject in fiber optics because of the possibilities for novel transmission properties. Although photonic crystal fibers based on photonic bandgap guidance are the most drastic innovation in this subject, optical fibers containing air holes but not having photonic crystal structures are also being intensively studied. Such air-silica microstructured fibers are more practical than the photonic bandgap fibers because the lack of photonic crystal structure makes the fabrication far easier. Even without the photonic bandgap, the microstructured fibers can exhibit valuable properties in terms of group velocity dispersion and nonlinearity, because the index contrast between air and silica is 10 or more times as large as that of the conventional optical fibers based on doped silica glasses. However, one of the major challenges for practical applications of the air-silica microstructured fibers has been their high transmission losses, which have been several tens to hundreds times higher than those of the conventional fibers. As a solution to this problem, we have proposed a more practical structure called hole-assisted lightguide fiber (HALF). In addition to the air holes for realizing novel optical properties, this structure has a material index profile for waveguiding, and hence is closer to the conventional fibers than the other microstructured fibers are. As a result, novel optical properties can be realized without severe degradation in transmission loss. In experiments, an anomalous group velocity dispersion as large as +35 ps/nm/km at 1550 nm wavelength, which would be unattainable in the conventional fibers, has been realized with a loss of 0.41 dB/km, which is comparable to those of the conventional fibers. Analyses of the losses of the fabricated HALFs suggest that the loss should be lowered by mitigating the effect of the drawing tension and minimizing the power fraction in the holes. It is also shown that the full-vector finite element method realizes accurate modeling of the properties such as dispersion and macrobend loss.

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The effect of dispersion on spectral broadening of incoherent continuous-wave light in optical fibers

Optics Express ◽

10.1364/oe.18.022393 ◽

2010 ◽

Vol 18 (21) ◽

pp. 22393 ◽

Cited By ~ 34

Author(s):

Daniel B. S. Soh ◽

Jeffrey P. Koplow ◽

Sean W. Moore ◽

Kevin L. Schroder ◽

Wen L. Hsu

Keyword(s):

Optical Fibers ◽

Continuous Wave ◽

Spectral Broadening ◽

Continuous Wave Light

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Watt-Level Visible Continuous-Wave Upconversion Fiber Lasers toward the “Green Gap” Wavelengths of 535–553 nm

ACS Photonics ◽

10.1021/acsphotonics.1c00452 ◽

2021 ◽

Author(s):

Shuaihao Ji ◽

Shaoqun Liu ◽

Xiuji Lin ◽

Yingyi Song ◽

Bo Xiao ◽

...

Keyword(s):

Fiber Lasers ◽

Continuous Wave

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Optoelectronic frequency-modulated continuous-wave terahertz spectroscopy with 4 THz bandwidth

Nature Communications ◽

10.1038/s41467-021-21260-x ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Lars Liebermeister ◽

Simon Nellen ◽

Robert B. Kohlhaas ◽

Sebastian Lauck ◽

Milan Deumer ◽

...

Keyword(s):

Fiber Optics ◽

Continuous Wave ◽

Dynamic Range ◽

Terahertz Spectroscopy ◽

Beat Signal ◽

Photonic Integration ◽

Terahertz Time Domain Spectroscopy ◽

Destructive Testing ◽

Optical Delay ◽

Broadband Terahertz

AbstractBroadband terahertz spectroscopy enables many promising applications in science and industry alike. However, the complexity of existing terahertz systems has as yet prevented the breakthrough of this technology. In particular, established terahertz time-domain spectroscopy (TDS) schemes rely on complex femtosecond lasers and optical delay lines. Here, we present a method for optoelectronic, frequency-modulated continuous-wave (FMCW) terahertz sensing, which is a powerful tool for broadband spectroscopy and industrial non-destructive testing. In our method, a frequency-swept optical beat signal generates the terahertz field, which is then coherently detected by photomixing, employing a time-delayed copy of the same beat signal. Consequently, the receiver current is inherently phase-modulated without additional modulator. Owing to this technique, our broadband terahertz spectrometer performs (200 Hz measurement rate, or 4 THz bandwidth and 117 dB peak dynamic range with averaging) comparably to state-of-the-art terahertz-TDS systems, yet with significantly reduced complexity. Thickness measurements of multilayer dielectric samples with layer-thicknesses down to 23 µm show its potential for real-world applications. Within only 0.2 s measurement time, an uncertainty of less than 2 % is achieved, the highest accuracy reported with continuous-wave terahertz spectroscopy. Hence, the optoelectronic FMCW approach paves the way towards broadband and compact terahertz spectrometers that combine fiber optics and photonic integration technologies.

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Novel Bloch wave excitation platform based on few-layer photonic crystal deposited on D-shaped optical fiber

Scientific Reports ◽

10.1038/s41598-021-90504-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Esteban Gonzalez-Valencia ◽

Ignacio Del Villar ◽

Pedro Torres

Keyword(s):

Optical Fibers ◽

High Performance ◽

Light Propagation ◽

Fiber Optic ◽

Layer Structure ◽

Optical Network ◽

Building Blocks ◽

Bloch Wave ◽

Nanophotonic Devices ◽

Wide Range

AbstractWith the goal of ultimate control over the light propagation, photonic crystals currently represent the primary building blocks for novel nanophotonic devices. Bloch surface waves (BSWs) in periodic dielectric multilayer structures with a surface defect is a well-known phenomenon, which implies new opportunities for controlling the light propagation and has many applications in the physical and biological science. However, most of the reported structures based on BSWs require depositing a large number of alternating layers or exploiting a large refractive index (RI) contrast between the materials constituting the multilayer structure, thereby increasing the complexity and costs of manufacturing. The combination of fiber–optic-based platforms with nanotechnology is opening the opportunity for the development of high-performance photonic devices that enhance the light-matter interaction in a strong way compared to other optical platforms. Here, we report a BSW-supporting platform that uses geometrically modified commercial optical fibers such as D-shaped optical fibers, where a few-layer structure is deposited on its flat surface using metal oxides with a moderate difference in RI. In this novel fiber optic platform, BSWs are excited through the evanescent field of the core-guided fundamental mode, which indicates that the structure proposed here can be used as a sensing probe, along with other intrinsic properties of fiber optic sensors, as lightness, multiplexing capacity and easiness of integration in an optical network. As a demonstration, fiber optic BSW excitation is shown to be suitable for measuring RI variations. The designed structure is easy to manufacture and could be adapted to a wide range of applications in the fields of telecommunications, environment, health, and material characterization.

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Shaping Beam Profiles Using Plastic Optical Fiber Tapers with Application to Ice Sensors

Sensors ◽

10.3390/s20092503 ◽

2020 ◽

Vol 20 (9) ◽

pp. 2503

Author(s):

Kostas Amoiropoulos ◽

Georgia Kioselaki ◽

Nikolaos Kourkoumelis ◽

Aris Ikiades

Keyword(s):

Fiber Optics ◽

Optical Fibers ◽

Laser Cooling ◽

Detection Efficiency ◽

Numerical Aperture ◽

Beam Profile ◽

Hollow Beam ◽

Enhanced Sensitivity ◽

Surface Irregularities ◽

Plastic Optical Fibers

Using either bulk or fiber optics the profile of laser beams can be altered from Gaussian to top-hat or hollow beams allowing enhanced performance in applications like laser cooling, optical trapping, and fiber sensing. Here, we report a method based on multimode Plastic Optical Fibers (POF) long-tapers, to tweak the beam profile from near Gaussian to a hollow beam, by generating surface irregularities on the conical sections of the taper with a heat-and-pull technique. Furthermore, a cutback technique applied on long tapers expanded the output beam profile by more than twice the numerical aperture (NA) of the fiber. The enhanced sensitivity and detection efficiency of the extended profile was tested on a fiber optical ice sensor related to aviation safety.

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