Spectral characteristics of side face excited microstructured fibers for photonic integrated circuits formations
I. V. Guryev, D. J. Vazquez, I. A. Sukhoivanov, C. H. Luna, J. M. Estudillo-Ayala, J. A. Andrade Lucio, R. M. Chavez, M. Trejo-Durán, E. Alvarado Mendez, R. Rojas-Laguna
We propose a new method for mass production of the photonic crystal devices on the basis of widely-known and well-developed technology such as microstructured optical fibers. In this paper, we investigate the optical properties of side-excited microstructured optical fiber and discuss the conditions for utilization such a structure as a planar photonic crystal device, namely, the high-quality resonance filter.
Graded index microstructured polymer optical fiber incorporating a specially designed air-hole array featuring variable air-hole diameters and inter-hole separation is proposed, fabricated and characterized in view of the fiber potential applications in low-loss, low-dispersion terahertz guidance. The proposed fiber features simultaneously low chromatic and intermodal dispersions, as well as low loss in the terahertz spectral range. We then experimentally demonstrate that proposed fibers exhibit smaller pulse distortion, larger bandwidth and more reliable excitation when compared to the porous…
We report on trapped pulse generation in birefringent microstructured optical fiber. Linearly polarized fs pulses are injected into the microstructured fiber in anomalous dispersion regime. We observed experimentally that soliton pulse polarized along the fast fiber axis partially transfers its energy to the orthogonal polarization. The generated pulse is amplified through the orthogonal Raman gain. The two polarization components are located at group-velocity matched wavelengths. The experimental works are supported with numerical simulations. The obtained results are important for the light …
We introduce a new simple design of hollow-core microstructured fiber targeted to guide mid-infrared light at a wavelength 2.94 $ μ$m. The fiber has a triangular-core supported via silica-glass webs enclosed by a large hollow capillary tube. The fiber specific dimensions are determined based on the guiding technique, which is based on the anti-resonant mechanism. For a triangular-core with side length $100$ $ μ$m, the fiber has a minimum transmission loss $0.08\pm0.005$ dB/m and dispersion 2.3 ps/km/nm at the operational wavelength 2.94 $ μ$m.
In the paper, we propose the new technology for mass production of the photonic crystal devices and all-optical integrated circuits. We carry out the brief analysis of positive and negative sides paying attention to recent advances in silicon fibers fabrication which is crucial moment in the proposed technology.
A simple self-referenced non destructive method is proposed for measuring the cutoff wavelength of microstructured optical fibers (MOFs). It is based on the analysis of the time dependent optical power transmitted through a bow-tie slit rotating in the far-field pattern of the fiber under test. As a first demonstration, the cutoff wavelength of a 2m MOF sample is measured with a precision of 10nm, in good agreement with theoretical predictions.
We report on the design of a highly-nonlinear specialty fiber as a mid-infrared light source at 4.3 μm. A meter length of the designed solid-core chalcogenide based index-guided microstructured optical fiber (MOF) with circular air holes has been exploited to translate wavelength via four wave mixing using a thulium-doped fiber laser as the pump with a relatively low peak power of 5 W. A peak gain value of around 37 dB with full width at half maxima (FWHM) less than 3 nm is achieved.
The thermal drift of the characteristic wavelength of fiber Bragg gratings (FBGs) photowritten in the core of microstructured fibers (MOFs) is significantly reduced by inserting a liquid of suitable refractive index into their holes. For instance, the spectral range of variations is divided by a factor of 4 over a temperature range larger than 20\degree C in a six-hole MOF, and the maximum sensitivity is reduced. Such passive FBG temperature compensation technique is of great interest for applications involving accurate sensing free of thermal effects.
We observe the dynamics of pulse trapping in a microstructured fiber. Few-cycle pulses create a system of two pulses: a Raman shifting soliton traps a pulse in the normal dispersion regime. When the soliton approaches a wavelength of zero group velocity dispersion the Raman shifting abruptly terminates and the trapped pulse is released. In particular, the trap is less than 4ps long and contains a 1ps pulse. After being released, this pulse asymmetrically expands to more than 10ps. Additionally, there is no disturbance of the trapping dynamics at high input pulse energies as the supercontinuum …
The optical properties of solid core microstructured optical fibers (SC MOFs) have been studied for a long time. The process of energy outflow of the core modes has always been associated with the process of constructive interference of the core modes fields under reflection from the photonic crystal cladding. In this paper, we want to offer a new look at the light localization in the core of SC MOFs related to the behavior of spin and orbital parts of the Poynting vector of these core modes and singularities arising in it.
In this paper we consider an interaction between the air core modes of hollow core waveguide microstructures and core cladding boundary walls in various shapes. The analysis is based on well established models such as the anti-resonant reflecting optical waveguide model and on the models proposed for the first time. In particular, we consider the dynamics of light localization in the polygonalcore cladding boundary wall as dependant on the type of its discrete rotational symmetry. Based on our findings we analyze the mechanisms of light localization in the core cladding boundary walls of negat…
This paper presents a theoretical design of chalcogenide glass based tapered microstructured optical fiber (MOF) to generate high power parabolic pulses (PPs) at the mid-IR wavelength (~ 2 μm). We optimize fiber cross-section by the multipole method and studied pulse evolution by well known Symmetrized Split-Step Fourier Method. Our numerical investigation reveals the possibility of highly efficient PP generation within a very short length (~ 18 cm) of this MOF for a Gaussian input pulse of 60 W peak power and FWHM of 3.5 ps. We examined quality of the generated PP by calculating the misfit pa…
We report a numerical study on generation and stability of parabolic pulses during their propagation through highly nonlinear specialty optical fibers. Here, we have generated a parabolic pulse at 2.1 $μ$m wavelength from a Gaussian input pulse with 1.9 ps FWHM and 75 W peak power after travelling through only 20 cm length of a chalcogenide glass based microstructured optical fiber (MOF). Dependence on input pulse shapes towards most efficient conversion into self similar states is reported. The stability in terms of any deviation from dissipative self-similar nature of such pulses has been an…
An all solid large modearea (LMA) chalcogenide based microstructured core optical fiber (MCOF) is designed and proposed for high power handling in the mid IR spectral regime, covering the entire second transparency window of the atmosphere (3 to 5 microns). The core of the proposed specialty fiber is composed of a few rings of high index rods arranged in a pattern of hexagon. Dependence of effective mode area on the pitch and radius of high index rods are studied. Ultra high effective mode area up to 75000 micron square can be achieved over this specific wavelength range while retaining its si…
We report two novel fabrication techniques, as well as spectral transmission and propagation loss measurements of the subwavelength plastic wires with highly porous (up to 86%) and non-porous transverse geometries. The two fabrication techniques we describe are based on the microstructured molding approach. In one technique the mold is made completely from silica by stacking and fusing silica capillaries to the bottom of a silica ampoule. The melted material is then poured into the silica mold to cast the microstructured preform. Another approach uses microstructured mold made of plastic which…
In this work, a novel infinity 3D printing technique is explored to fabricate continuous multi-meter-long low-loss near-zero dispersion suspended-core polypropylene fibers for application in terahertz (THz) communications. Particular attention is paid to process parameter optimization for 3D printing with low-loss polypropylene plastic. Three microstructured THz fibers were 3D printed using the standard and infinity 3D printers, and an in-depth theoretical and experimental comparison between the fibers were carried out. Transmission losses (by power) of 4.79 dB/m, 17.34 dB/m and 11.13 dB/m are…
The dispersion of index-guiding microstructured polymer optical fibers is calculated for second-harmonic generation. The quadratic nonlinearity is assumed to come from poling of the polymer, which in this study is chosen to be the cyclic olefin copolymer Topas. We found a very large phase mismatch between the pump and the second-harmonic waves. Therefore the potential for cascaded quadratic second-harmonic generation is investigated in particular for soliton compression of fs pulses. We found that excitation of temporal solitons from cascaded quadratic nonlinearities requires an effective quad…
As photon mixing is not inherently limited to any specific spectral region, parametric processes represent a compelling solution for all-optical signal processing in spectral windows not easily accessible by other technologies. Particularly, the continuous-wave pumping scheme is essential for any application requiring modulated signals or precise spectroscopic characterization. Highly nonlinear fibers enabled record performances for wavelength conversion and amplification in the telecommunication band, however no waveguiding platforms have yet solved the trade-off between high-nonlinearity, lo…
We derive a sufficient condition for the existence of index-guided modes in a very general class of dielectric waveguides, including photonic-crystal fibers (arbitrary periodic claddings, such as ``holey fibers''), anisotropic materials, and waveguides with periodicity along the propagation direction. This condition provides a rigorous guarantee of cutoff-free index-guided modes in any such structure where the core is formed by increasing the index of refraction (e.g. removing a hole). It also provides a weaker guarantee of guidance in cases where the refractive index is increased ``on average…
In this paper we present a theoretical and numerical analysis of light localization in hollow core microstructured fibers (HCMFs) with a complicated shape of the core cladding boundary. The analysis is based on well established models (for example, the ARROW model) and also on the models proposed for the first time. In particular, we consider local and nonlocal mechanisms of light localization in the waveguide structures with a determined type of discrete rotational symmetry of the core cladding boundary. We interpret and analyze mechanisms of light localization in negative curvature hollow co…
Optical fibers are widely used in bioimaging systems as flexible endoscopes capable of low-invasive penetration inside hollow tissue cavities. Here, we report on the technique which allows magnetic resonance imaging (MRI) of hollow-core microstructured fibers (HC-MFs), paving the way for combing MRI and optical bioimaging. Our approach is based on Layer-by-Layer assembly of oppositely charged polyelectrolytes and magnetite nanoparticles on the inner core surface of HC-MFs. Incorporation of magnetite nanoparticles into polyelectrolyte layers renders HC-MFs visible for MRI and induces the red-sh…
We report design of an efficient ~ 50 cm long all-fiber compact microstructured optical fiber-based 3-4.25 um mid-IR light source with power conversion efficiency > 28% by exploiting FWM with Er3+-doped ZBLAN fiber as the pump.
The photonic crystal fibers (PCF) or air-silica microstructured fibers consist of a periodic array of dielectric transverse. By introducing a defect in this structure, it is possible to guide the light by a photonic bandgap effect, whose properties are different fundamentally from the guide by total internal reflection that takes place in conventional fibers. PCF with two cores have significant potential, and this is one of the main motivations witches led us to approach this theme in this article. Analysis of the inter-core coupling was also necessary to study the problem of crosstalk. Their …
We present a formal analogy between the eigenvalue problem for guided scalar modes in a low-contrast photonic bandgap fiber and quasi-stationary TM modes of a two-dimensional (2D) photonic structure. Using this analogy, we numerically study the confinement losses of disordered microstructured fibers through the leakage rate of an open 2D system with high refractive index inclusions. Our results show that for large values of the disorder, the confinement losses increase. However, they also suggest that losses might be improved in strongly disordered fibers by exploring ranges of physical parame…
The waveguiding properties of two silica-based airguiding photonic bandgap fiber designs are investigated with special emphasis on material effects. The nonlinear coefficients are found to be 1-2 orders of magnitude smaller than those obtained in index-guiding microstructured fibers with large mode areas. The material dispersion of silica makes a significant contribution to the total chromatic dispersion although less than 10% of the field energy is located in the silica regions of the fibers. These findings suggest that dispersion engineering through the choice of base material may be a possi…
We introduce a small-core air-guiding photonic crystal fiber whose cladding is made of improved air-silica photonic crystal with non-circular air holes placed in triangular lattice. The fiber achieves un-disturbed bandgap guidance over 350nm wavelength range.
Soliton-soliton collisions have a crucial role in enhancing the spectrum of dispersive waves in optical fibers and collisions among in-phase solitons lead to a dramatic enhancement of the dispersive wave power, as well as to its significant spectral reshaping. We obtained a simple analytical model to estimate the spectral position, width and amplitude of the dispersive waves induced by a collision of two in-phase solitons. We tested our theory in the case of a dual concentric core microstructured fiber.
Optical waveguide segments based on geometrically unbound photonic crystal fibers (PCF) designs could be exploited as building blocks to realize miniaturized complex devices which implement advanced photonic operations. Here, we show how to fabricate optical waveguide segments with PCF designs by direct high-resolution 3D printing and how the combination of these segments can realise complex photonic devices. We demonstrate the unprecedented precision and flexibility of our method by fabricating the first-ever fiber polarising beam splitter based on PCFs. The device was directly printed in one…
The field energy distributions and effective mode areas of silica-based photonic bandgap fibers with a honeycomb airhole structure in the cladding and an extra airhole defining the core are investigated. We present a generalization of the common effective area definition, suitable for the problem at hand, and compare the results for the photonic bandgap fibers with those of index-guiding microstructured fibers. While the majority of the field energy in the honeycomb photonic bandgap fibers is found to reside in the silica, a substantial fraction (up to ~30%) can be located in the airholes. Thi…
The efficiency of evanescent coupling between a silica optical fiber taper and a silicon photonic crystal waveguide is studied. A high reflectivity mirror on the end of the photonic crystal waveguide is used to recollect, in the backwards propagating fiber mode, the optical power that is initially coupled into the photonic crystal waveguide. An outcoupled power in the backward propagating fiber mode of 88% of the input power is measured, corresponding to a lower bound on the coupler efficiency of 94%.
Photonic crystal fibers represent one of the most active research fields in modern fiber optics. The recent advancements of topological photonics have inspired new fiber concepts and designs. Here, we demonstrate a new type of topological photonic crystal fibers based on second order photonic corner modes from the Su-Schrieffer-Heeger model. Different from previous works where the in-plane properties at $k_z=0$ have been mainly studied, we find that in the fiber configuration of $k_z>0$, a topological bandgap only exists when the propagation constant $k_z$ along the fiber axis is larger than a…
A single-mode all-silica photonic crystal fiber with an effective area of 600 square-micron and low bending loss is demonstrated. The fiber is characterized in terms of attenuation, chromatic dispersion and modal properties.
We experimentally compare the optical bandwidth of a conventional single-mode fiber (SMF) with 3 different photonic crystal fibers (PCF) all optimized for visible applications. The spectral attenuation, single-turn bend loss, and mode-field diameters (MFD) are measured and the PCF is found to have a significantly larger bandwidth than the SMF for an identical MFD. It is shown how this advantage can be utilized for realizing a larger MFD for the PCF while maintaining a bending resistant fiber.
We report on a polarization maintaining large mode area photonic crystal fiber. Unlike, previous work on polarization maintaining photonic crystal fibers, birefringence is introduced using stress applying parts. This has allowed us to realize fibers, which are both single mode at any wavelength and have a practically constant birefringence for any wavelength. The fibers presented in this work have mode field diameters from about 4 to 6.5 micron, and exhibit a typical birefringence of 1.5e-4.
We report generation of broadband low divergent supercontinuum over the entire wavelength window of 1.5 to 3.5 μm from a 2.25 meter long effective single moded photonic bandgap fiber with mode area of 1100 μm2.
Typically, photonic waveguides designed for nonlinear frequency conversion rely on intuitive and established principles, including index guiding and band gap engineering, and are based on simple shapes with high degrees of symmetry. We show that recently developed inverse-design techniques can be applied to discover new kinds of microstructured fibers and metasurfaces designed to achieve large nonlinear frequency conversion efficiencies. As a proof of principle, we demonstrate complex, wavelengthscale chalcogenide glass fibers and gallium phosphide metasurfaces exhibiting some of the largest n…
We demonstrate a simple and rapid epoxy-based method for transferring photonic crystal cavities to the facets of optical fibers. Passive Si cavities were measured via fiber taper coupling as well as direct transmission from the fiber facet. Active quantum dot containing GaAs cavities showed photoluminescence that was collected both in free space and back through the original fiber. Cavities maintain a high quality factor (2000-4000) in both material systems. This new design architecture provides a practical mechanically stable platform for the integration of photonic crystal cavities with macr…
We analyze the guiding problem in a realistic photonic crystal fiber using a novel full-vector modal technique, a biorthogonal modal method based on the nonselfadjoint character of the electromagnetic propagation in a fiber. Dispersion curves of guided modes for different fiber structural parameters are calculated along with the 2D transverse intensity distribution of the fundamental mode. Our results match those achieved in recent experiments, where the feasibility of this type of fiber was shown.
We study the class of endlessly single-mode all-silica photonic crystal fibers with a triangular air-hole cladding. We consider the sensibility to longitudinal nonuniformities and the consequences and limitations for realizing low-loss large-mode area photonic crystal fibers. We also discuss the dominating scattering mechanism and experimentally we confirm that both macro and micro-bending can be the limiting factor.
We consider chromatic dispersion of capillary tubes and photonic crystal fibers infiltrated with liquid crystals. A perturbative scheme for inclusion of material dispersion of both liquid crystal and the surrounding waveguide material is derived. The method is used to calculate the chromatic dispersion at different temperatures.
Results from the calculation of the basic characteristics of the photonic crystal fiber with two rings of holes are presented by the approach which takes into account the exact distribution of the refractive index over the cross section of the photonic crystal fiber. Formulae are theoretically derived for the calculation of holes with arbitrary shapes by dividing the material within them into rotated at different angles rectangles. Keywords: photonic crystal fibre, Galerkin method, a set of sine functions, local coordinate systems.
Quasi error-free 10 Gbit/s data transmission is demonstrated over a novel type of 50 micron core diameter photonic crystal fiber with as much as 100 m length. Combined with 850$ nm VCSEL sources, this fiber is an attractive alternative to graded-index multi-mode fibers for datacom applications. A comparison to numerical simulations suggests that the high bit-rate may be partly explained by inter-modal diffusion.
For the first time, we demonstrated that a hyper-broadband from 2μm to 10μm can be generated with a high spectral flatness by using a ~4 um pump and an As2Se3 photonic crystal fiber. The broad and flat dispersion profile and the low guiding loss of the endlessly single-mode As2Se3 photonic crystal fibers combining with the high nonlinearity and wide mid-infrared transparent window of As2Se3 chalcogenide glass are essential for this high performance mid-infrared laser source.
We build ring resonators to assess the potentialities of Kagome Hollow-Core Photonic Crystal Fibers for future applications to resonant rotation sensing. The large mode diameter of Kagome fibers permits to reduce the free space fiber-to-fiber coupling losses, leading to cavities with finesses of about 30 for a diameter equal to 15 cm. Resonance linewidths of 3.2~MHz with contrasts as large as 89\% are obtained. Comparison with 7-cell photonic band gap (PBG) fiber leads to better finesse and contrast with Kagome fiber. Resonators based on such fibers are compatible with the angular random walk …
Structured light have made deep impacts on modern biotechnology and clinical practice, with numerous optical systems and lasers currently being used in medicine to treat disease. We demonstrate a new concept of fiber-based optical hook scalpel. The subwavelength photonic hook is obtained in the vicinity of a shaped fiber tip with asymmetric radiation. A 1550 nm continuous-wave source, commonly used for medical imaging, has been required. Photonic hook with a lateral feature size less than the half-wavelength is achieved using a hemispherical shaped fiber tip with metallic mask. This breakthrou…
Optical fiber tapers are used to collect photoluminescence emission at ~1.5 um from photonic crystal cavities fabricated in erbium doped silicon nitride on silicon. Photoluminescence collection via fiber taper is enhanced 2.5 times relative to free space, with a total taper collection efficiency of 53%. By varying the fiber taper offset from the cavity, a broad tuning range of coupling strength is obtained. This material system combined with fiber taper collection is promising for building on-chip optical amplifiers.
We demonstrate experimentally that the spectral broadening of CW supercontinuum can be controlled by using photonic crystal fibers with two zero-dispersion wavelengths pumped by an Yb fiber laser at 1064 nm. The spectrum is bounded by two dispersive waves whose spectral location depends on the two zero-dispersion wavelengths of the fiber. The bandwidth of the generated spectrum and the spectral power density may thus be tailored for particular applications, such as high-resolution optical coherence tomography or optical spectroscopy.
Transient fully reconfigurable photonic circuits can be introduced at the optical fiber surface with subangstrom precision. A building block of these circuits, a 0.7 angstrom-precise nano-bottle resonator, is experimentally created by local heating, translated, and annihilated.
We present highly sensitive refractometers based on a long-period grating in a large mode area PCF. The maximum sensitivity is 1500 nm/RIU at a refractive index of 1.33, the highest reported for any fiber grating. The minimal detectable index change is $2\times 10^{-5}$. The high sensitivity is obtained by infiltrating the sample into the holes of the photonic crystal fiber to give a strong interaction between the sample and the probing field.
The possibility of soliton self-compression of ultrashort laser pulses down to the few-cycle regime in photonic crystal fibers is numerically investigated. We show that efficient sub-two-cycle temporal compression of nanojoule-level 800 nm pulses can be achieved by employing short (typically 5-mm-long) commercially available photonic crystal fibers and pulse durations of around 100 fs, regardless of initial linear chirp, and without the need of additional dispersion compensation techniques. We envisage applications in a new generation of compact and efficient sub-two cycle laser pulse sources.
In this paper we propose a new hypothesis of out of plane band gap formation in all solid photonic band gap (PBG) fibers. At first, one considers the process of the core modes formation as a result of excitation of continuous mode spectrum of single dielectric rod of the cladding. It is shown that the core modes can be considered as transverse resonance of a set of the radiation modes decoupled from the continuum provided that the phase matching condition for the propagation constants are fulfilled. An analogy between the core mode formation in all solid PBG fibers and formation of bound state…
In a recent paper, Subbaraman et al report a theoretical and numerical study of highly dispersive pure silica photonic crystal fiber supporting group-velocity dispersion exceeding -2*10^4 ps/nm/km. This comment argues that the authors only consider one out of the two sides of the same coin, by not taking the corresponding beating length into account.
Based on a recent formulation of the V-parameter of a photonic crystal fiber we provide numerically based empirical expressions for this quantity only dependent on the two structural parameters - the air hole diameter and the hole-to-hole center spacing. Based on the unique relation between the V-parameter and the equivalent mode field radius we identify how the parameter space for these fibers is restricted in order for the fibers to remain single mode while still having a guided mode confined to the core region.
