Showing papers on "Photonic-crystal fiber published in 2015"
TL;DR: An overview of the technologies used to implement surface plasmon resonance (SPR) effects into fiber-optic sensors for chemical and biochemical applications and a survey of results reported over the last ten years is presented.
Abstract: This paper presents a brief overview of the technologies used to implement surface plasmon resonance (SPR) effects into fiber-optic sensors for chemical and biochemical applications and a survey of results reported over the last ten years. The performance indicators that are relevant for such systems, such as refractometric sensitivity, operating wavelength, and figure of merit (FOM), are discussed and listed in table form. A list of experimental results with reported limits of detection (LOD) for proteins, toxins, viruses, DNA, bacteria, glucose, and various chemicals is also provided for the same time period. Configurations discussed include fiber-optic analogues of the Kretschmann–Raether prism SPR platforms, made from geometry-modified multimode and single-mode optical fibers (unclad, side-polished, tapered, and U-shaped), long period fiber gratings (LPFG), tilted fiber Bragg gratings (TFBG), and specialty fibers (plastic or polymer, microstructured, and photonic crystal fibers). Configurations involving the excitation of surface plasmon polaritons (SPP) on continuous thin metal layers as well as those involving localized SPR (LSPR) phenomena in nanoparticle metal coatings of gold, silver, and other metals at visible and near-infrared wavelengths are described and compared quantitatively.
555 citations
TL;DR: A surface plasmon resonance (SPR) sensor based on photonic crystal fiber with selectively filled analyte channels with maximum amplitude sensitivity and maximum refractive index (RI) sensitivity is proposed, suitable for detecting various high RI chemicals, biochemical and organic chemical analytes.
Abstract: We propose a surface plasmon resonance (SPR) sensor based on photonic crystal fiber (PCF) with selectively filled analyte channels. Silver is used as the plasmonic material to accurately detect the analytes and is coated with a thin graphene layer to prevent oxidation. The liquid-filled cores are placed near to the metallic channel for easy excitation of free electrons to produce surface plasmon waves (SPWs). Surface plasmons along the metal surface are excited with a leaky Gaussian-like core guided mode. Numerical investigations of the fiber’s properties and sensing performance are performed using the finite element method (FEM). The proposed sensor shows maximum amplitude sensitivity of 418 Refractive Index Units (RIU−1) with resolution as high as 2.4 × 10−5 RIU. Using the wavelength interrogation method, a maximum refractive index (RI) sensitivity of 3000 nm/RIU in the sensing range of 1.46–1.49 is achieved. The proposed sensor is suitable for detecting various high RI chemicals, biochemical and organic chemical analytes. Additionally, the effects of fiber structural parameters on the properties of plasmonic excitation are investigated and optimized for sensing performance as well as reducing the sensor’s footprint.
239 citations
TL;DR: An overview of recent advances in the random fiber laser field, including high-power and high-efficiency generation, spectral and statistical properties of random fiber lasers, nonlinear kinetic theory of such systems, and emerging applications in telecommunications and distributed sensing are provided.
Abstract: Random fiber lasers blend together attractive features of traditional random lasers, such as low cost and simplicity of fabrication, with high-performance characteristics of conventional fiber lasers, such as good directionality and high efficiency. Low coherence of random lasers is important for speckle-free imaging applications. The random fiber laser with distributed feedback proposed in 2010 led to a quickly developing class of light sources that utilize inherent optical fiber disorder in the form of the Rayleigh scattering and distributed Raman gain. The random fiber laser is an interesting and practically important example of a photonic device based on exploitation of optical medium disorder. We provide an overview of recent advances in this field, including high-power and high-efficiency generation, spectral and statistical properties of random fiber lasers, nonlinear kinetic theory of such systems, and emerging applications in telecommunications and distributed sensing.
236 citations
TL;DR: This work allows the feasibility of using the D-shaped hollow-core MOFs to develop a high-sensitivity, real-time and distributed SPR sensor to solve the phase matching and analyte filling problems in the microstructured optical fiber (MOF) sensors.
Abstract: To solve the phase matching and analyte filling problems in the microstructured optical fiber (MOF)-based surface plasmon resonance (SPR) sensors, we present the D-shaped hollow core MOF-based SPR sensor. The air hole in the fiber core can lower the refractive index of a Gaussian-like core mode to match with that of a plasmon mode. The analyte is deposited directly onto the D-shaped flat surface instead of filling the fiber holes. We numerically investigate the effect of the air hole in the core on the SPR sensing performance, and identify the sensor sensitivity on wavelength, amplitude and phase. This work allows us to determine the feasibility of using the D-shaped hollow-core MOFs to develop a high-sensitivity, real-time and distributed SPR sensor.
233 citations
TL;DR: Experimental results show that the proposed sensor can provide an ultra-high RI sensitivity of 30899 nm/RIU, which has potential applications in fields such as gas concentration analyzing and humidity monitoring.
Abstract: An ultra-high sensitivity open-cavity Fabry–Perot interferometer (FPI) gas refractive index (RI) sensor based on the photonic crystal fiber (PCF) and Vernier effect is proposed and demonstrated. The sensor is prepared by splicing a section of PCF to a section of fiber tube fused with a section of single mode fiber. The air holes running along the cladding of the PCF enable the gas to enter or leave the cavity freely. The reflection beam from the last end face of the PCF is used to generate the Vernier effect, which significantly improves the sensitivity of the sensor. Experimental results show that the proposed sensor can provide an ultra-high RI sensitivity of 30899 nm/RIU. This sensor has potential applications in fields such as gas concentration analyzing and humidity monitoring.
227 citations
TL;DR: A low-loss suspended core As(38)Se(62) fiber with core diameter of 4.5 μm and a zero-dispersion wavelength of 3.5μm was used for mid-infrared supercontinuum generation and was in good correspondence with the calculated dispersion.
Abstract: A low-loss suspended core As(38)Se(62) fiber with core diameter of 4.5 μm and a zero-dispersion wavelength of 3.5 μm was used for mid-infrared supercontinuum generation. The dispersion of the fiber was measured from 2.9 to 4.2 μm and was in good correspondence with the calculated dispersion. An optical parametric amplifier delivering 320 fs pulses with a peak power of 14.8 kW at a repetition rate of 21 MHz was used to pump 18 cm of suspended core fiber at different wavelengths from 3.3 to 4.7 μm. By pumping at 4.4 μm with a peak power of 5.2 kW coupled to the fiber a supercontinuum spanning from 1.7 to 7.5 μm with an average output power of 15.6 mW and an average power >5.0 μm of 4.7 mW was obtained.
184 citations
20 Jul 2015
TL;DR: In this article, the first femtosecond fiber laser operating near 3μm was reported, based on nonlinear polarization evolution in an Er3+-doped fluoride glass fiber with an estimated peak power of 3.5kW.
Abstract: Ultrafast fiber lasers operating in the near-infrared have revolutionized laser science by enabling numerous breakthroughs in both fundamental science and industrial applications. In this Letter, we extend the spectral coverage of these laser sources to the mid-infrared by reporting the first femtosecond fiber laser operating near 3 μm. This passively mode-locked fiber ring laser based on nonlinear polarization evolution in an Er3+-doped fluoride glass fiber generates 207 fs pulses at 2.8 μm with an estimated peak power of 3.5 kW. This demonstration paves the way for further developments of promising applications in the molecular fingerprint region such as frequency comb spectroscopy.
183 citations
TL;DR: In this article, a simple hexagonal lattice photonic crystal fiber biosensor using surface plasmon resonance phenomenon was proposed, where the analyte (sample) was placed outside the fiber structure instead of inside the air-holes.
Abstract: We propose a simple, two rings, hexagonal lattice photonic crystal fiber biosensor using surface plasmon resonance phenomenon. An active plasmonic gold layer and the analyte (sample) are placed outside the fiber structure instead of inside the air-holes, which will result in a simpler and straight forward fabrication process. The proposed sensor exhibits birefringent behavior that enhances its sensitivity. Numerical investigation of the guiding properties and sensing performance are conducted by finite element method. Using wavelength and amplitude interrogation methods, the proposed sensor could provide maximum sensitivity of 4000 nm/RIU and 320 RIU $^{-1}$ , respectively. The resolutions of the sensor are $2.5 \times 10^{-5}$ and $3.125 \times 10^{-5}$ RIU for wavelength and amplitude interrogation modes. The proposed sensor design shows promising results that could be used in biological and biochemical analytes detection.
175 citations
TL;DR: This work provides the first evidence for solitons involving more than a few modes, and for spatiotemporal multimode soliton fission and Raman shifting, in multimode opticalsolitons with up to roughly 10 spatial modes.
Abstract: As optical fiber communications and fiber lasers approach fundamental limits there is considerable interest in multimode fibers. In nonlinear science, they represent an exciting environment for complex nonlinear waves. As in single-mode fiber, solitons may be particularly important. Multimode solitons consist of synchronized, non-dispersive pulses in multiple spatial modes, which interact via the Kerr nonlinearity of the fiber. They are expected to exhibit novel spatiotemporal characteristics, dynamics and, like single-mode solitons, may provide a convenient intuitive tool for understanding more complex nonlinear phenomena in multimode fibers. Here we explore experimentally and numerically basic properties and spatiotemporal behaviors of these solitons: their formation, fission, and Raman dynamics.
165 citations
20 Apr 2015
TL;DR: In this paper, a hydrogen-filled kagome-style hollow-core photonic crystal fiber (kagomePCF) was used to generate a supercontinuum, spanning more than three octaves from 124-nm to beyond 1200-nm.
Abstract: Although supercontinuum sources are readily available for the visible and near infrared (IR), and recently also for the mid-IR, many areas of biology, chemistry, and physics would benefit greatly from the availability of compact, stable, and spectrally bright deep-ultraviolet and vacuum-ultraviolet (VUV) supercontinuum sources Such sources have, however, not yet been developed Here we report the generation of a bright supercontinuum, spanning more than three octaves from 124 nm to beyond 1200 nm, in hydrogen-filled kagome-style hollow-core photonic crystal fiber (kagome-PCF) Few-microjoule, 30 fs pump pulses at wavelength of 805 nm are launched into the fiber, where they undergo self-compression via the Raman-enhanced Kerr effect Modeling indicates that before reaching a minimum subcycle pulse duration of ∼1 fs, much less than one period of molecular vibration (8 fs), nonlinear reshaping of the pulse envelope, accentuated by self-steepening and shock formation, creates an ultrashort feature that causes impulsive excitation of long-lived coherent molecular vibrations These phase modulate a strong VUV dispersive wave (at 182 nm or 68 eV) on the trailing edge of the pulse, further broadening the spectrum into the VUV The results also show for the first time that kagome-PCF guides well in the VUV
160 citations
TL;DR: A compact, low loss, and highly sensitive optical fiber curvature sensor is presented, which allows for using either visibility or spectral shift for sensor interrogation when the device is bent.
Abstract: A compact, low loss, and highly sensitive optical fiber curvature sensor is presented. The device consists of a few-millimeter-long piece of seven-core fiber spliced between two single-mode fibers. When the optical fiber device is kept straight, a pronounced interference pattern appears in the transmission spectrum. However, when the device is bent, a spectral shift of the interference pattern is produced, and the visibility of the interference notches changes. This allows for using either visibility or spectral shift for sensor interrogation. The dynamic range of the device can be tailored through the proper selection of the length of the seven-core fiber. The effects of temperature and refractive index of the external medium on the response of the curvature sensor are also discussed. Linear sensitivity of about 3000 nm/mm−1 for bending was observed experimentally.
TL;DR: In this article, the authors summarized the recent achievements in the area of ultrafast fiber lasers mode-locked with low-dimensional nanomaterials: graphene, topological insulators (Bi2Te3, Bi2Se3, Sb2Te), and transition metal sulfide semiconductors, like molybdenum disulfide (MoS2).
Abstract: The paper summarizes the recent achievements in the area of ultrafast fiber lasers mode-locked with so-called low-dimensional nanomaterials: graphene, topological insulators (Bi2Te3, Bi2Se3, Sb2Te3), and transition metal sulfide semiconductors, like molybdenum disulfide (MoS2). The most important experimental achievements are described and compared. Additionally, new original results on ultrashort pulse generation at 1.94 μm wavelength using graphene are presented. The designed Tm-doped fiber laser utilizes multilayer graphene as a saturable absorber and generates 654 fs pulses at 1940 nm wavelength, which are currently the shortest pulses generated from a Tm-doped fiber laser with a graphene-based saturable absorber.
TL;DR: The results demonstrate that the cell-type WS2 nanosheets SA can serve as a good candidate for short-pulse mode locker.
Abstract: A cell-type saturable absorber has been demonstrated by filling the single mode photonic crystal fiber (SMPCF) with tungsten disulfide (WS2) nanosheets. The modulation depth, saturable intensity and non-saturable loss of this SA are measured to be 3.53%, 159 MW/cm2 and 23.2%, respectively. Based on this SA, a passively mode-locked EDF laser has been achieved with pulse duration of 808 fs and repetition rate of 19.57 MHz and signal-noise-ratio (SNR) of 60.5 dB. Our results demonstrate that the cell-type WS2 nanosheets SA can serve as a good candidate for short-pulse mode locker.
TL;DR: In this paper, the first inscription of fiber Bragg gratings (FBGs) in cyclic transparent optical polymer (CYTOP)-perfluorinated polymer optical fibers (POFs) was reported.
Abstract: We report on the first inscription of fiber Bragg gratings (FBGs) in cyclic transparent optical polymer (CYTOP)-perfluorinated polymer optical fibers (POFs). We have used a direct write method with a femtosecond laser operating in the visible. The FBGs have a typical reflectivity of 70%, a bandwidth of 0.25 nm, a 3-mm length, and an index change of $\sim 10^{-4}$ . The FBGs operate in the $C$ -band, where CYTOP offers key advantages over polymethyl methacrylate optical fibers, displaying significantly lower optical loss in the important near-infrared (NIR) optical communications window. In addition, we note that CYTOP has a far lower affinity for water absorption and a core-mode refractive index that coincides with the aqueous index regime. These properties offer several unique opportunities for POF sensing at NIR wavelengths, such as compatibility with existing optical networks, the potential for POF sensor multiplexing and suitability for biosensing. We demonstrate compatibility with a commercial Bragg grating demodulator.
TL;DR: The use of the multimode graded-index fibers in the taper can significantly relax the adiabaticity requirement in comparison with using single-mode fibers.
Abstract: We demonstrate the first all-fiber mode-group-selective photonic lantern using multimode graded-index fibers. Mode selectivity for mode groups LP01, LP11 and LP21+LP02 is 20-dB, 10-dB and 7-dB respectively. The insertion loss when butt coupled to multimode graded-index fiber is below 0.6-dB. The use of the multimode graded-index fibers in the taper can significantly reduce the adiabaticity requirement.
TL;DR: A tunable and switchable dual-wavelength ultra-fast Tm-doped fiber laser based on nonlinear polarization evolution (NPE) technique in a passively mode-locked laser cavity to effectively alleviate mode competition and enables the multiwavelength mode locking.
Abstract: We propose and demonstrate a tunable and switchable dual-wavelength ultra-fast Tm-doped fiber laser. The tunability is based on nonlinear polarization evolution (NPE) technique in a passively mode-locked laser cavity. The NPE effect induces wavelength-dependent loss in the cavity to effectively alleviate mode competition and enables the multiwavelength mode locking. The laser exhibits tunable dual-wavelength mode locking over a wide range from 1852 to 1886 nm. The system has compact structure and both the wavelength tuning and switching capabilities can be realized by controlling the polarization in the fiber ring cavity.
TL;DR: Low-loss all-fiber photonic lantern (PL) mode multiplexers capable of selectively exciting the first six fiber modes of a multimode fiber and the use of graded index fibers in a PL eases the length requirements of the adiabatic tapered transition and could enable scaling to large numbers are demonstrated.
Abstract: Low-loss all-fiber photonic lantern (PL) mode multiplexers (MUXs) capable of selectively exciting the first six fiber modes of a multimode fiber (LP01, LP11a, LP11b, LP21a, LP21b, and LP02) are demonstrated. Fabrication of the spatial mode multiplexers was successfully achieved employing a combination of either six step or six graded index fibers of four different core sizes. Insertion losses of 0.2-0.3 dB and mode purities above 9 dB are achieved. Moreover, it is demonstrated that the use of graded index fibers in a PL eases the length requirements of the adiabatic tapered transition and could enable scaling to large numbers.
TL;DR: It is shown that the proposed PCF structures exhibit high relative sensitivity, high birefringence and low confinement losses simultaneously for various analytes.
Abstract: In this paper, we report a design of high sensitivity Photonic Crystal Fiber (PCF) sensor with high birefringence and low confinement losses for liquid analyte sensing applications. The proposed PCF structures are designed with supplementary elliptical air holes in the core region vertically-shaped V-PCF and horizontally-shaped H-PCF. The full vectorial Finite Element Method (FEM) simulations performed to examine the sensitivity, the confinement losses, the effective refractive index and the modal birefringence features of the proposed elliptical air hole PCF structures. We show that the proposed PCF structures exhibit high relative sensitivity, high birefringence and low confinement losses simultaneously for various analytes.
TL;DR: In this article, the topological insulator (TI) nanosheets solution filled in photonic crystal fiber can operate as an effective saturable absorber (SA) with the merits of low insertion loss (sim 0.42$ dB), long interaction length (>10 cm), and high power tolerance.
Abstract: We first reported that the topological insulator (TI) nanosheets solution filled in photonic crystal fiber can operate as an effective saturable absorber (SA) with the merits of low-insertion loss ( $\sim 0.42$ dB), long interaction length (>10 cm), and high-power tolerance. This SA device exhibited a saturable intensity of 14.9 MW/ $\mathrm{cm}^{2}$ , modulation depth of 19.1%, and nonsaturable loss of 25% at 1060 nm. Upo employing, this device rendered us to establish an ytterbium-doped all-fiber laser oscillator, where stable evanescent wave mode-locking operation has been achieved. This letter provided a new way of utilizing the unique nonlinear optical property of TI.
TL;DR: A particular photonic crystal fiber designed with all circle air holes is proposed that can realize high birefringence, high nonlinearity, and low confinement loss.
Abstract: A particular photonic crystal fiber (PCF) designed with all circle air holes is proposed. Its characteristics are studied by full-vector finite element method (FEM) with anisotropic perfectly matched layer (PML). The simulation results indicated that the proposed PCF can realize high birefringence (up to 10(-2)), high nonlinearity (50W(-1)·km(-1) and 68W(-1)·km(-1) in X and Y polarizations respectively) and low confinement loss (less than 10(-3)dB/km at 1.55um wavelength).
TL;DR: Loss spectra, dispersion and detection capability of the proposed biosensor for the two fundamental modes (HE(11)(x) and HE(y)) have been elucidated using a Finite Element Method (FEM) and Perfectly Matching Layers (PML).
Abstract: This paper presents a theoretical investigation of a novel holey fiber (Photonic Crystal Fiber (PCF)) multi-channel biosensor based on surface plasmon resonance (SPR). The large gold coated micro fluidic channels and elliptical air hole design of our proposed biosensor aided by a high refractive index over layer in two channels enables operation in two modes; multi analyte sensing and self-referencing mode. Loss spectra, dispersion and detection capability of our proposed biosensor for the two fundamental modes (HE11x and HE11y) have been elucidated using a Finite Element Method (FEM) and Perfectly Matching Layers (PML).
TL;DR: In this paper, two kinds of novel plasmonic high sensitivity of refractive index (RI) sensors based on analyte-filled photonic crystal fiber (AF-PCF) are proposed.
Abstract: Two kinds of novel plasmonic high sensitivity of refractive index (RI) sensors based on analyte-filled photonic crystal fiber (AF-PCF) are proposed in this paper. The metallic gold and silver is used as the surface plasmon resonance activity metal. A full-vector finite-element method is applied to analyze and investigate the sensing and coupling characteristics of this designed AF-PCF with the gold or silver layer. Phase matching between the second surface plasmon polariton and fundamental modes can be met at different wavelengths as the analyte of the RI is increased from 1.40 to 1.42. The phase-matching wavelength of the designed AF-PCF with the gold layer is shifted to the longer wavelength direction compared with that with the silver layer, and the resonance strength is much stronger. The average sensitivities of 7040 and 7017 nm/RIU in the sensing are arranged from 1.40 to 1.42 with high linearity are achieved for the designed sensors with the gold and silver layers, respectively, which are almost the same. However, the figure of merit with the silver layer is much better than that with the gold layer.
TL;DR: In this paper, the authors make a comprehensive study on a highly efficient half-open cavity design for high power random fiber laser (RFL) and optimize the fiber length for getting higher output power within the scheme, i.e., shorter fiber length is preferred for efficiently harvesting the first order random lasing at the open end of the cavity.
Abstract: In this paper, we make a comprehensive study on a highly efficient half-open cavity design for high power random fiber laser (RFL). With the theoretical analysis, we optimize the cavity's fiber length for getting higher output power within the scheme, i.e., shorter fiber length is preferred for efficiently harvesting the first order random lasing at the open end of the cavity. As the verification of the theory, we experimentally demonstrate a high output power (7 W), highly efficient (70% optical conversion efficiency) RFL working at 1140 nm, using 10 W 1090 nm laser as the pump source and only 1 km standard single-mode fiber as the distributed cavity.
TL;DR: WDM transmission was successfully demonstrated over 1.15 km of low-loss hollow core photonic bandgap fiber (HC-PBGF) and over 1 km of solid core fiber (SCF), and it is concluded that the OSNR penalty associated with the SCF is minimal.
Abstract: We show for the first time 100 Gbit/s total capacity at 2 µm waveband, using 4 × 9.3 Gbit/s 4-ASK Fast-OFDM direct modulation and 4 × 15.7 Gbit/s NRZ-OOK external modulation, spanning a 36.3 nm wide wavelength range. WDM transmission was successfully demonstrated over 1.15 km of low-loss hollow core photonic bandgap fiber (HC-PBGF) and over 1 km of solid core fiber (SCF). We conclude that the OSNR penalty associated with the SCF is minimal, while a ~1-2 dB penalty was observed after the HC-PBGF probably due to mode coupling to higher-order modes.
TL;DR: A Mach-Zehnder interferometer based on a twin-core fiber that exhibited a high gas pressure sensitivity and a low temperature cross-sensitivity makes it very suitable for highly-sensitive gas pressure sensing in harsh environments.
Abstract: A Mach-Zehnder interferometer based on a twin-core fiber was proposed and experimentally demonstrated for gas pressure measurements. The in-line Mach-Zehnder interferometer was fabricated by splicing a short section of twin-core fiber between two single mode fibers. A micro-channel was created to form an interferometer arm by use of a femtosecond laser to drill through one core of the twin-core fiber. The other core of the fiber was remained as the reference arm. Such a Mach-Zehnder interferometer exhibited a high gas pressure sensitivity of −9.6 nm/MPa and a low temperature cross-sensitivity of 4.4 KPa/°C. Moreover, ultra-compact device size and all-fiber configuration make it very suitable for highly-sensitive gas pressure sensing in harsh environments.
TL;DR: In this article, a very low attenuation of 175dB/km at 480nm was achieved by hollow core optical fibers with an extended transmission bandwidth in the near infrared and with very low optical attenuation in the visible wavelength regime.
Abstract: Hollow core antiresonant fibers offer new possibilities in the near infrared and visible spectral range. I show here that the great flexibility of this technology can allow the design and fabrication of hollow core optical fibers with an extended transmission bandwidth in the near infrared and with very low optical attenuation in the visible wavelength regime. A very low attenuation of 175 dB/km at 480 nm is reported. A modification of the design of the studied fibers is proposed in order to achieve fast-responding gas detection.
TL;DR: In this paper, photonic wire bonding is demonstrated to enable highly efficient coupling between multicore fibers and planar silicon photonic circuits, which relies on in-situ fabrication of three-dimensional interconnect waveguides between the fiber facet and tapered silicon-on-insulator waveguiders.
Abstract: Photonic wire bonding is demonstrated to enable highly efficient coupling between multicore fibers and planar silicon photonic circuits. The technique relies on in-situ fabrication of three-dimensional interconnect waveguides between the fiber facet and tapered silicon-on-insulator waveguides. Photonic wire bonding can easily compensate inaccuracies of core placement in the fiber cross-section, does not require active alignment, and is well suited for automated fabrication. We report on the design, on fabrication, and on characterization of photonic wire bonds. In a proof-of-principle experiment, a four-core fiber is coupled to a silicon photonic chip, leading to measured coupling losses as small as 1.7 dB.
TL;DR: 3D printing of optical preforms signals a new milestone in optical fiber manufacture, and 3D printers capable of processing soft glasses, silica, and other materials are likely to come on line in the not-so-distant future.
Abstract: A structured optical fiber is drawn from a 3D-printed structured preform. Preforms containing a single ring of holes around the core are fabricated using filament made from a modified butadiene polymer. More broadly, 3D printers capable of processing soft glasses, silica, and other materials are likely to come on line in the not-so-distant future. 3D printing of optical preforms signals a new milestone in optical fiber manufacture.
TL;DR: A new family of mechanochromic photonic-crystal fibers exhibits tunable structural colors under stretching and experiences reversible and rapid multicolor changes during the stretch and release processes, for example, between red, green, and blue.
Abstract: A new family of mechanochromic photonic-crystal fibers exhibits tunable structural colors under stretching. This novel mechanochromic fiber is prepared by depositing polymer microspheres onto a continuous aligned-carbon-nanotube sheet that has been wound on an elastic poly(dimethylsiloxane) fiber, followed by further embedding in poly(dimethylsiloxane). The color of the fiber can be tuned by varying the size and the center-to-center distance of the polymer spheres. It further experiences reversible and rapid multicolor changes during the stretch and release processes, for example, between red, green, and blue. Both the high sensitivity and stability were maintained after 1000 deformation cycles. These elastic photonic-crystal fibers were woven into patterns and smart fabrics for various display and sensing applications.
TL;DR: The first direct carrier-envelope-offset (CEO) frequency detection of a modelocked laser based on supercontinuum generation (SCG) in a CMOS-compatible silicon nitride (Si(3)N(4)) waveguide is presented.
Abstract: We present the first direct carrier-envelope-offset (CEO) frequency detection of a modelocked laser based on supercontinuum generation (SCG) in a CMOS-compatible silicon nitride (Si(3)N(4)) waveguide. With a coherent supercontinuum spanning more than 1.5 octaves from visible to beyond telecommunication wavelengths, we achieve self-referencing of SESAM modelocked diode-pumped Yb:CALGO lasers using standard f-to-2f interferometry. We directly obtain without amplification strong CEO beat signals for both a 100-MHz and 1-GHz pulse repetition rate laser. High signal-to-noise ratios (SNR) of > 25 dB and even > 30 dB have been generated with only 30 pJ and 36 pJ of coupled pulse energy from the megahertz and gigahertz laser respectively. We compare these results to self-referencing using a commercial photonic crystal fiber and find that the required peak power for CEO beat detection with a comparable SNR is lowered by more than an order of magnitude when using a Si(3)N(4) waveguide.