Mode Area Photonic Crystal Fiber Research Articles

Numerical investigation of a wideband supercontinuum source based on a large-mode-area photonic crystal fiber pumped at 1.3 μm

A numerical investigation was conducted to obtain a supercontinuum spanning about two octaves using a large mode area photonic crystal fiber (PCF) pumped at 1.3 μm. In our study, a 1.3 μm femtosecond laser and a silica-based large mode area PCF were selected as the pump source and nonlinear medium, respectively. The nonlinear Schrodinger equation was solved with split-step Fourier method to simulate the evolution of pulse and the broadening of spectrum. The effect of several parameters including the length of PCF, the pulse width, and the average pump power on characteristics of the output spectrum was studied. The simulation results revealed that the supercontinuum extended from near 600 nm to over 2450 nm at 20 dB with length of 30 cm, pulse width of 100 fs and average power of 12 W, respectively. This work proved this large mode area PCF a potentially excellent medium for supercontinuum source and provided some theoretical guidance for future experiments.

A large effective mode area photonic crystal fiber supporting 134 OAM modes

A large effective mode area photonic crystal fiber supporting 134 OAM modes

Design of photonic crystal fiber with large mode area for flat-top mode generation

We report a large mode area photonic crystal fiber with a flat-top mode field. The optical fiber has a multi-layer square structure with air holes and doped layer. A flat and top-hat-like mode intensity profile is provided through the reasonable design of the doped layer. The modal characteristics including effective mode area, dispersion, bending loss, confinement loss and field profile are investigated. The proposed fiber with a top-hat mode generation has potential applications in laser drilling, laser cleaning, imaging, spectroscopy, and so on.

Fibre laser system with wavelength tuning in extended telecom range

We report on a laser system on the base of a fibre telecom source, a chirped pulse amplification system, and low-birefringence large mode area photonic crystal fibre (LMA PCF) generating ∼ 100 fs pulses with the energy ∼ 10 nJ in the 1600–1700 nm wavelength range. The characteristics of the output spectrum corresponding to Raman solitons are studied for different polarisations of the pump pulse at the input of the PCF. We have shown that the wavelength of the output spectrum maximum can be tuned in the whole long (L) and ultra-long (U) telecom bands by adjusting the polarisation state of the pump pulse while the output power is constant.

HYPHa project: a low-cost alternative for integrated photonics

In this paper, a brief introduction to the Hybrid sensor platforms of integrated photonic systems based on ceramic and polymer materials (HYPHa) is presented. The project's goal is to establish a collaborative effort of institutes specialized in integrated optics. The newly formed group of professionals will be founded on research groups' experience, collaboration, and devotion. We intend to develop a method for combining competencies and a universal material platform for integrated photonics, based on newly validated hybrid materials as part of the project. Silica compounds with additions including TiO2, SnO2, used as structural matrices, polymer coatings with dopants (active or protective layers), organic dyes, and active two-dimensional materials such as transition metal dichalcogenides, graphene hybrids, and boron nitride will be the foundation for these materials. Full Text: PDF ReferencesK. Rola, A. Zajac, M. Czajkowski, A. Szpecht, M. Zdonczyk, M. Smiglak, J. Cybinska, K. Komorowska, "Ionic liquids for active photonics components fabrication", Opt. Mater. 89, 106-111 (2019). CrossRef D. Kowal, K. Rola, J. Cybinska, M. Skorenski, A. Zajac, A. Szpecht, M. Smiglak, S. Drobczynski, K. Ciesiolkiewicz, K. Komorowska, "Fluorescent ionic liquid micro reservoirs fabricated by dual-step E-beam patterning", Mater. Res. Bull. 142, 111434 (2021). CrossRef T. Martynkien, J. Olszewski, M. Szpulak, G. Golojuch, W. Urbanczyk, T. Nasilowski, F. Berghmans, and H. Thienpont, "Experimental investigations of bending loss oscillations in large mode area photonic crystal fibers", Opt. Express 15, 13547-13556 (2007). CrossRef E. Środa, J. Olszewski, and W. Urbańczyk, "Reducing bend-induced loss and crosstalk in a two-mode ridge waveguide by steplike thickness structuring", Appl. Opt. 61, 1164-1170 (2022). CrossRef P. Karasinski, C. Tyszkiewicz, A. Domanowska, A. Michalewicz, J. Mazur, "Low loss, long time stable sol–gel derived silica–titania waveguide films", Mater. Lett. 143, 5-7 (2015). CrossRef P. Karasinski, C. Tyszkiewicz, A. Maciaga, I.V. Kityk, E. Gondek, "Two-component waveguide SiO2:TiO2 films fabricated by sol–gel technology for optoelectronic applications", J. of Mater. Sci.: Mater. Electron. 26, 2733-2736 (2015). CrossRef M.A. Butt, A. Kazmierczak, C. Tyszkiewicz, P. Karasinski, R. Piramidowicz, "Mode Sensitivity Exploration of Silica–Titania Waveguide for Refractive Index Sensing Applications", Sensors 21, 7452 (2021). CrossRef A. Kazmierczak, M. Slowikowski, K. Pavlov, M. Filipiak, M. Vervaeke, C. Tyszkiewicz, H. Ottevaere, R. Piramidowicz, P. Karasinski, "Efficient, low-cost optical coupling mechanism for TiO2-SiO2 sol-gel derived slab waveguide surface grating coupler sensors", Opt. Appl. 50, 539 (2020). CrossRef M.A. Butt, S.N. Khonina, N.L. Kazanskiy, "A highly sensitive design of subwavelength grating double-slot waveguide microring resonator", Laser Phys. Lett. 17, 076201 (2020). CrossRef N.L. Kazanskiy, M.A. Butt, S.N. Khonina, "Silicon photonic devices realized on refractive index engineered subwavelength grating waveguides-A review", Opt. Laser Technol. 138, 106863 (2021). CrossRef M.A. Butt, S.N. Khonina, N.L. Kazanskiy, "Recent advances in photonic crystal optical devices: A review", Opt. Laser Technol. 142, 107265 (2021). CrossRef L. Xu, Y. Wang, E. El-Fiky, D. Mao, A. Kumar, Z. Xing, Md. G. Saber, M. Jacques, D.V. Plant, "Compact Broadband Polarization Beam Splitter Based on Multimode Interference Coupler With Internal Photonic Crystal for the SOI Platform", J. Light. Technol. 37, 1231 (2019). CrossRef R. Marchetti, C. Lacava, A. Khokhar, X. Chen, I. Cristiani, D.J. Richardson, G. T. Reed, P. Petropoulos, P. Minzioni, "High-efficiency grating-couplers: demonstration of a new design strategy", Sci. Rep. 7, 16670 (2017). CrossRef

Highly fluorine and ytterbium doped polarization maintaining large mode area photonic crystal fiber via the sol-gel process

Highly Yb-doped silica glass with low refractive index for fabrication of Yb-doped large-mode-area photonic crystal fiber (LMA PCF) is in favor of decreasing fiber length and thus increasing the threshold of nonlinear effects in pulse laser amplification. Accordingly, fluorine incorporation in highly Yb-doped silica glass is vitally important to compensate the sharp increase in refractive index caused by ytterbium and aluminum ions. In this work, the fluorine doping concentration in Yb/Al/P/F co-doped silica glass was significantly improved by a modified sol-gel method combined with high temperature sintering. The effects of fluorine doping on glass structure have been investigated in details by Raman spectra, nuclear magnetic resonance (NMR) and advanced pulse electron paramagnetic resonance (EPR) measurements. The incorporation of fluorine yields Si-F bonds and Yb-F bonds formation and leads to the mild change in spectroscopic properties. An optimized silica core glass rod with high Yb (0.77 wt.%) and fluorine (0.8 wt.%) doping concentration, low refractive index and acceptable optical quality was prepared. Based on the highly fluorine and ytterbium doped silica core glass, a polarization maintaining (PM) photonic crystal fiber with 40 µm core was prepared and the pump absorption coefficient at 976 nm was ∼6.5 dB/m. An average amplified power of 103 W was achieved from a 2-m-long PCF with the bend diameter of 23 cm. The slope efficiency (with respect to pump power) was 52% with laser beam quality factor M2 of 1.46.

Design and analysis for large-mode-area photonic crystal fiber with negative-curvature air ring

A large mode area photonic crystal fiber (LMA-PCF) under standard fiber size is proposed in this paper. In order to realize large mode field and low bending loss, multilayer negative curvature air ring structure is designed. The finite element method with perfectly matched layer boundaries is used to analyze the performance of PCF. The influence of various parameters of fiber structure on fiber performance is analyzed. Numerical results show that the structure can achieve large mode area with lower bending loss and smaller bending radius in the wavelength range of 1–1.8 µm. Under the condition of a five-layer six-lobed air ring with negative curvature, the mode field area reaches 1358.9 μm2. At the same time, the high-to-fundamental mode loss ratio reaches 331.5. When the bending radius is 15 cm, the bending loss of the fundamental mode is 0.21 dB/m. Within the 360° bending direction, LMA can be realized in all directions and has effective single-mode operation.

Large Mode Area Photonic Crystal Fiber with Low Dispersion and Confinement Loss for Terahertz Wave Guiding

A photonic crystal fiber (PCF) made of the cyclic-olefin copolymer (COC) with low dispersion and confinement loss, large-mode-area, and single-mode transmission for terahertz wave guiding is described. The characteristics of the PCF in the terahertz range are simulated and analyzed by the full-vector finite element method (FEM). The effects of the structural parameters on the performance of the terahertz PCF are also investigated. The effective mode field area of the PCF is as large as 1.22084 × 107 μm2 at a wavelength of 1,000 μm and a flat dispersion of 0.07669 ± 0.33258 ps/nm/km is obtained. A much lower confinement loss of 6.0253 × 10-16 dB/m is achieved. The single mode transmission over the entire terahertz wave band is described.

兆瓦峰值功率输出的超低纤芯数值孔径大模场光子晶体光纤

兆瓦峰值功率输出的超低纤芯数值孔径大模场光子晶体光纤

Optimal Design of Large Mode Area Photonic Crystal Fibers Using a Multiobjective Gray Wolf Optimization Technique

A new multiobjective optimization framework is presented for designing large mode area photonic crystal fibers (LMA-PCFs) with effective single-mode operation in the bent state. For optimizing the structure, we utilize the multiobjective gray wolf optimizer (MOGWO) to maximize the effective mode area (EMA) and the bending loss of higher order modes (HOMs), while minimizing the fundamental mode (FM) loss. The simulation results demonstrate that this framework enables us to improve the EMA by a factor of 1.26 and increase (decrease) the bending loss of the HOMs (the FM) by a factor of 7 (17), compared to the nonoptimal design. In addition, we investigate the dependence of the optical characteristics of the optimized LMA-PCFs on the wavelength and the bending radius. We found that some optimal structures are highly wavelength dependent and are not suitable for wideband applications. Furthermore, we found that the HOM loss is very sensitive to the bending radius. The proposed framework is comprehensive and can be employed to find a broad range of optimal designs for a wide range of applications.

Picosecond supercontinuum generation in large mode area photonic crystal fibers for coherent anti-Stokes Raman scattering microspectroscopy

We perform a detailed theoretical and experimental investigation of supercontinuum generation in large-mode-area photonic crystal fibers pumped by a high-energy, high-repetition rate picosecond Nd:YVO4 laser, with the goal of using it as the Stokes beam in coherent anti-Stokes Raman scattering setup. We analyze the influence of fiber structure and length on the supercontinuum power, spectral shape, and group delay dispersion. We identify the experimental conditions for stable supercontinuum generation, with microjoule-level pulse energy and the spectrum extending beyond 1600 nm, which allows excitation of Raman frequencies up to 3000 cm−1 and beyond. We demonstrate reliable and efficient operation of a coherent anti-Stokes Raman spectroscopy and microscopy setup using this supercontinuum source.

Manipulating refractive index, homogeneity and spectroscopy of Yb3+-doped silica-core glass towards high-power large mode area photonic crystal fiber lasers.

Output power scaling of single mode large mode area (LMA) photonic crystal fiber (PCF) amplifiers urgently requires the low refractive index of Yb3+-doped silica glasses whilst maintaining high optical homogeneity. In this paper, we report on a promising alternative Yb3+/Al3+/F-/P5+-co-doped silica core-glass (YAFP), which is prepared by modified sol-gel method developed by our group and highly suitable for fabricating high power LMA PCF amplifiers. By controlling the doping combinations of Al3+/F-/P5+ in Yb3+-doped silica glass,it not only ensures low refractive index (RI) but also maintains the excellent optical homogeneity and spectroscopic properties of Yb3+. The spectroscopic properties of Yb3+ ions have not deteriorated by the co-doping of F- and P5+ in YAFP glass compared with that of Yb3+/Al3+ co-doped silica glass. A large-size (⌀5 mm × 90 mm) YAFP silica-core glass rod with low average RI difference of 2.6 × 10-4 (with respect to pure silica glass), and low radial and axial RI fluctuations of ~2 × 10-4, was prepared. A LMA PCF with 50 µm core diameter was obtained by stack-capillary-draw techniques using YAFP core glass. Its core NA is 0.027. An average amplified power of 97 W peaking at 1030 nm and light-light efficiency of 54% are achieved from a 6.5 m long PCF in the pulse amplification laser experiment. Meanwhile, quasi-single-mode transmission is obtained with laser beam quality factor M2 of 1.4.

Fiber-based 1150-nm femtosecond laser source for the minimally invasive harmonic generation microscopy.

Harmonic generation microscopy (HGM) has become one unique tool of optical virtual biopsy for the diagnosis of cancer and the in vivo cytometry of leukocytes. Without labeling, HGM can reveal the submicron features of tissues and cells in vivo. For deep imaging depth and minimal invasiveness, people commonly adopt 1100- to 1300-nm femtosecond laser sources. However, those lasers are typically based on bulky oscillators whose performances are sensitive to environmental conditions. We demonstrate a fiber-based 1150-nm femtosecond laser source, with 6.5-nJ pulse energy, 86-fs pulse width, and 11.25-MHz pulse repetition rate. It was obtained by a bismuth borate or magnesium-doped periodically poled lithium niobate (MgO:PPLN) mediated frequency doubling of the 2300-nm solitons, generated from an excitation of 1550-nm femtosecond pulses on a large mode area photonic crystal fiber. Combined with a home-built laser scanned microscope and a tailor-made frame grabber, we achieve a pulse-per-pixel HGM imaging in vivo at a 30-Hz frame rate. This integrated solution has the potential to be developed as a stable HGM system for routine clinical use.

Analysis on the optical properties for the ytterbium doped silica glasses prepared by laser sintering technology

The paper demonstrates the optical properties of the ytterbium doped silica glasses that were fabricated by laser sintering technology combined with liquid phase doping method, and analyzed the influence of the fabricated process on the formation of Yb2+. The spectral parameters and laser performance parameters were also calculated and analyzed. The results indicate that the formation of Yb2+ can be effectively restrained through the optimized preparation process. The prepared ytterbium doped silica glass presents typical absorption and emission cross sections of Yb3+, and possesses attractive laser performance parameters. The material would have potential applications for the gain medium of large mode area photonic crystal fiber lasers.

Highly birefringent large mode area photonic crystal fiber-based sensor for interferometry applications

In this work, highly birefringent large mode area (LMA) photonic crystal fiber (PCF) structure for interferometric sensor applications is proposed. The effective mode area, birefringence and the sensitivity coefficient of the proposed PCF structure by employing the full vectorial finite element method (FV-FEM) have been thoroughly investigated. The numerical results have shown that proposed structure simultaneously offers high birefringence of order 10[Formula: see text], adequately LMA and high sensitivity for various liquid analytes by employing the elliptical liquid core holes.

High numerical aperture large-core photonic crystal fiber for a broadband infrared transmission

In this paper we present a large mode area photonic crystal fiber made of the heavy metal oxide glass CS-740, dedicated for a broadband light guidance in the visible, near- and mid-infrared regions of wavelengths from 0.4 to 4.7μm. The fiber is effectively multi-mode in the considered wavelength range. It is composed of a ring of air-holes surrounding the core, with a high linear filling factor of 0.97. The fiber was made using a standard stack-and-draw technique. Each hole has a size of approx. 2.5×3.0μm and diameter of core is 80μm. Fiber attenuation is below 3dB/m in the 0.9–1.7μm wavelength range, while at 4.4μm (mid-IR) it is approx. 5dB/cm. Bending loss at the 1.55μm wavelength is 0.45dB per loop of 8mm radius. Fiber numerical aperture is 0.53 at 1.55μm. The effective mode area of the fundamental mode is approx. 2400μm2 in the wavelength range of 0.8–1.7μm. We present a proof-of-concept demonstration that our large core photonic crystal fiber is able to efficiently collect light directly from a mid-IR quantum cascade laser without use of additional optics and can be used for pigtailing mid-IR sources and detectors.

Yb-doped silica glass and photonic crystal fiber based on laser sintering technology

We demonstrate the fabricating method for Yb3+-doped silica glass and double-cladding large mode area photonic crystal fiber (LMA PCF) based on laser sintering technology combined with a liquid phase doping method. The doped material prepared shows the amorphous property and the hydroxyl content is approximately 40 ppm. The attenuation of the fabricated LMA PCF is 14.2 dB m−1 at 976 nm, and the lowest value is 0.25 dB m−1 at 1200 nm. The laser slope efficiency is up to 70.2%.

Investigation of Temperature Sensitivity Under the Influence of Coupling Strength Between a Silica Core and a Satellite Waveguide in a Photonic Crystal Fiber with Selective Infiltration of Glycerin

In this report, we carry out simulation and experimental investigations of directional coupler structures with different separations between the glycerin selectively infiltrated channel and silica core of a large mode area Photonic Crystal Fiber (PCF). We assess their coupling characteristics and the corresponding temperature sensing capabilities. The temperature sensitivities of the glycerin selectively infiltrated channel adjacent to the silica core and two periods away from the silica core are −3.115nm/°C and −2.332nm/°C respectively. The glycerin selectively infiltrated channel three periods away from the silica core displays −107.8 pm/°C, an order of magnitude less temperature sensitive. The simulation results agree with the experimental results that there is a strong correlation between the coupling strength of the glycerin selectively infiltrated channel and the silica core, affecting its temperature response.

大模场面积光子晶体光纤全正色散自相似锁模激光器

大模场面积光子晶体光纤全正色散自相似锁模激光器

Fabrication and laser performance of Yb3+/Al3+ co-doped photonic crystal fiber synthesized by plasma nonchemical vapor deposition method

In this paper, the bulk Yb3+/Al3+ co-doped silica glass with 1.3 Yb2O3–2.5Al2O3–96.2SiO2(wt%) are synthesized by plasma nonchemical vapor deposition method combining solution doping technology, where the inductively coupled plasma is used as the heat source. The influence of different O2/N2 ratios on the fluorescence properties of Yb3+/Al3+ co-doped silica glass are investigated. The large mode area photonic crystal fiber (PCF) is fabricated by using the bulk Yb3+/Al3+ co-doped silica glass as fiber core. The laser performance of Yb3+/Al3+ co-doped photonic crystal fiber is studied.