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We report an experimental study on transmission of orbital angular momentum mode in antiresonant fibers generated with a dedicated all-fiber optical vortex phase mask. The vortex generator can convert Gaussian beam into vortex beams with topological charge l = 1. Generated vortex beam is directly butt-coupled into the antiresonant fiber and propagates over distance of 150 cm. The stability and sensitivity of the transmitted vortex beam on the external perturbations including bending, axial stress, and twisting is investigated. We demonstrate distortion-free vortex propagation for the axial stress force below 0.677 N, a bend radius greater than 10 cm.

The development of gradient index free-form micro-optic components dedicated to the mid-infrared range is challenging due to the lack of appropriate technology. We propose a method for developing gradient index components for broadband infrared range beyond the transmission window of silicate glass based on nanostructurization using a stack-and-draw fiber drawing technique. A proof-of-concept microlens is developed and verified experimentally in the wavelength range 1.5–4.3 µm. The microlenses are composed of a set of nanorods with a diameter of 940 nm made of a pair of SiO2-PbO-Bi2O3-Ga2O3 based glasses ordered into the preliminary calculated binary pattern. The pattern forms effectively continuous parabolic refractive index distribution for infrared range according to Maxwell-Garnett effective medium model. The development of individual microlenses with a diameter of 118 µm and focal length of 278 µm at the wavelength of 3.75 µm are reported. A large array of 737 microlenses with an individual diameter of 125 µm and focal length of 375 µm is also presented and analyzed.

We present an experimental study on generation and transmission of optical vortex in an all-fiber system consisting of an antiresonant fiber butt-coupled with a dedicated fiber-based vortex generator. The influence of external perturbations like fiber bend, axial stress on structural stability of the transmitted vortex in the antiresonant fiber is also reported.

The power scaling of single mode fiber lasers and amplifiers, due to the wide area of applications, has been the subject of great interest for many years. Increasing the mode area seems to be the obvious way to scale up the output power level from the single emitter if you consider well-known limitations like nonlinear effects, material damage threshold or thermal lensing. The nanostructurization of the fiber core is a method to control precisely optical properties of the active fiber. This method allows to design and develop the fiber with the core of any arbitrary defined refractive index distribution, with precision not available with other known fiber technology. The nanostructurization also open up an opportunity to incorporate simultaneously various active and non-active glasses into the fiber core. Those advantages can be used to fabricate the new class of fibers for laser applications. Here we show ytterbium doped phosphate single-mode fiber with nanostructured core, which is the first proof-of-concept of active fiber with entirely nanostructured core area.

Diffractive optical elements (DOE) are widely used in many different types of optical systems. These components played an enabling role e.g. in miniaturization of optical systems used in telecommunication, imaging and lithography, biomedical devices, optical sensors, vision correction and cameras.

Glasses based on SiO2-PbO-CdO-Ga2O3 system have been studied for the first time for fabrication of mid-infrared optical elements. Gallium oxide concentration was gradually increased, replacing silicon dioxide, for different cadmium and lead oxide content. The thermal and optical properties were investigated for different compositions. It was observed that the thermal stability, refractive index, and the transmission in the infrared range increased with increase of gallium and lead concentrations. The most thermally stable glass composition was selected for fabrication of optical elements such as optical fibers. We also successfully fabricated mid-infrared lenses by hot embossing for potential application in compact gas detectors.

We study optical performance of a vortex beam converter comprising a nanostructured gradient index vortex mask, a compact gradient index microlens and an optical fiber. The converter generates high quality focused optical vortex from the input Gaussian beam without support of any additional external optical elements. Integration of a nanostructured lens allows control of the size and the position of focus of vortex beams, while at the same time maintaining their quality. This confirms that nanostructured gradient index micro-optical components can be used sequentially to form complex optical systems and maintain full compatibility with fiber optics. Our experimental results are supported by numerical simulations.

Nanostructured GRIN components are optical elements which can have an arbitrary refractive index profile while retaining flat-parallel entry and exit facets. A method of their fabrication requires assembly of large quantities of glass rods in order to satisfy subwavelength requirement of the effective medium theory. In this paper, we present a development of gradient index microlenses using a combination of methods: nanostructurization of the preform and controlled diffusion process during lens drawing on a fiber drawing tower. Adding a diffusion process allows us to overcome limits of the effective medium theory related to maximum size of nanorods in the lens structure. We show that nanorods are dissolved during the fiber drawing process in high temperature and glass components are locally quasi-uniformly distributed. To demonstrate feasibility of the proposed approach, we have developed and experimentally verified the performance of a nGRIN microlens with a diameter of 115 µm composed of 115 rods on the diagonal, and length of 200 µm devoted to work for the wavelength over 658 nm.

In this paper we present a light field camera system where a flat-surface hexagonal array of nanostructured gradient index lenses was used as a lens matrix. In our approach we use an array of 469 gradient index microlenses with a diameter of 20 µm and 100% fill factor. To develop the single lens and the lenslet array we used a modified stack-and-draw technology. In this technique, variation of refractive index is achieved by using quantized gradient index profiles and rods from different types of glasses. We show experimental results of using this type of lenses for imaging in a system of two kinds of light field cameras. In the first one, the microlens array is located in the focal plane of the main lens. The image is reconstructed, in this case using a Fourier slice photography algorithm. This allowed a partial reconstruction of a 3D scene with spatial and depth resolution of 20 µm and field of view of 500×500×500 µm. In the second configuration, the microlens array is located between a sample and a microscopic objective, thus allowing for superresolution 3D reconstruction of a microscopic image. The scale-invariant feature transform method was used for image reconstruction and obtained a partial 3D reconstruction with a field of view of 150×115×80 µm and a spatial resolution of 2 µm and depth resolution of 10 µm.

The series of SiO2-Bi2O3-PbO-ZnO-BaO and SiO2-TiO2-Bi2O3-PbO-Na2O glasses were synthetized to obtain non-crystallizing materials, dedicated to fabrication of photonic crystal fibers. During composition development, the thermal properties were investigated according to the change of chemical composition. The glasses contain high concentrations of heavy metal oxides for high refractive index, large nonlinear refractive index and spectrally broad transmission window from 0.5 to 4.5 μm. Their thermal properties are optimized to enable drawing of all-solid glass photonic crystal fibers in tandem with previously designed highly nonlinear glass PBG81 based on SiO2-Ga2O3-Bi2O3-PbO-CdO system. This creates novel dual glass combinations for PCF fibers. We have also investigated influence of melting conditions on the final thermal and optical properties, including absorption from water contamination at around 2.8 μm.

We present composition development of borosilicate glasses for fabrication of high refractive index contrast, all-solid photonic crystal fibers. An oxide system composed of SiO 2 B 2 O 3 Al 2 O 3 Li 2 O Na 2 O K 2 O was adjusted to match thermal properties of selected highly nonlinear, lead bismuth gallium silicate glass. A high difference of refractive index of 0.376 is achieved at a wavelength of 1550 nm. We proved experimentally that the developed pair of glasses enables to draw optical fibers, and we propose a design of a photonic crystal fiber structure for broadband supercontinuum generation.

Publisher’s Note: This conference presentation, originally published on 23 May 2018, was withdrawn on 18 July 2019 per author request

Nanostructured gradient index (nGRIN) elements are a new class of planar-surface micro-optical elements. An effective gradient index profile with any arbitrary refractive index distribution can be developed with internal discrete nanostructure composed of two types of glasses. A low-cost modified stack-and-draw technology commonly used for photonic crystal fibres development is used for development of nGRIN components and fibers. The effective medium Maxwell-Garnett theory is applied to describe performance of the components. We report on recent progress in development of nanostructured core fibres and a wide range of nGRIN micro-optical components as microlenses, axicons, vortices and diffractive optical elements.

The development of single mode fibre lasers and amplifiers, due to the wide area of applications, is the topic of great interest. We present nanostructurization, the new method applied within the fibre core to control precisely optical properties of the active fibre. The nanostructured core is composed of two or more kind of glasses with the size of a fraction of the light wavelength. The glass areas are made with glass rods creating the structure, repetitive along the fibre. The refractive index of that kind material can be treated as a compound of refractive indices of each glass area averaged over a certain neighbourhood inside the material. It results in continuous-like refractive index profile according to the design, which can be described with effective medium theory. The nanostructurization opens new opportunities for development of fibres with a core composed of glasses doped with active or photosensitive ions. It allows to control precisely not only the refractive index distribution, but also the active dopants distribution or photosensitivity distribution in the fibre core, providing perspectives for novel optical fibre designs for laser applications. We introduce recent developments of nanostructured core fibres made of ytterbium doped phosphate and silica glass. Active fibres with additional germanium dopants are also reviewed.

Higher order modes (HOM) in optical fibres exhibit many interesting properties. Among others they have non-Gaussian electric field distributions, complex polarization patterns, unique waveguide dispersion profiles and distinctive propagation characteristics. Therefore, HOMs are used in various types of photonic devices. Here we report on modelling, development and optical characterization of photonic crystal fibers (PCFs) designed especially for the purpose of coupling, guiding and controlling HOMs. In our analysis we concentrate on Mexican sombrero” (HE 12 ) and “doughnut” (HE 21 , HE 11 TM 01 , TE 01 ) modes. We show how to selectively tune their propagation properties and tailor the losses to fit specific applications.

We report on efficient inscription of fiber Bragg gratings (FBGs) in a new type of single mode fiber with nanostructured core and with an effective parabolic graded index profile, using the standard phase mask method and a 248 nm pulsed laser. A nanostructured core allows to obtain high concentration of GeO2 in subwavelength glass rods and simultaneously to maintain low average germanium dopant level of silica similarly to standard single mode fibers. We showed that in a nanostructured core fiber, a factor of 3 better efficiency in gratings inscription was achieved, although the fiber has 20% lower average concentration of GeO2 with respect to SMF-28. In the nanostructured fiber we obtained a significant improvement in temperature sensitivity, while the strain sensitivity of FBG in nGRIN optical fiber is the same as in case of standard single-mode fiber (SMF-28). We have measured the strain sensitivity of 0.72 × 10−6 1/μe (1.11 pm/μe@1.53μm), and the temperature sensitivity is about 30% higher than for FBG in SMF-28 and equals to 10.2 × 10−6 1/K (15.6 pm/K@1.53μm).

Nanostructured GRIN components are optical elements which can have arbitrary refractive index profile while retaining flat-parallel entry and exit facets. They are composed of more than 9000 individually placed glass subwavelength rods made of two types of glass with different refractive indices. They are developed using a standard stack-and-draw method used for fibre drawing. The refractive index profile of the nanostructured GRIN element can be described by the effective refractive index theory when the diameter of the individual rods are sufficiently smaller than the wavelength. In this paper we show that use of glasses designed for high diffusion and high temperatures during drawing process allows to develop parabolic nanostructured GRIN microlenses with rod diameter larger than wavelength. In particular, we have developed a GRIN microlens with diameter of 115 μm composed of 115 rods on diagonal. Our GRIN microlens has a length of 200 μm and a working distance equal to 1.05 mm, with focal spot of 8.5 μm measured for the 658 nm wavelength. We experimentally verified its imaging properties. Image resolution higher than 3.25 μm was measured.

In this work, the technique of hot embossing has been applied for the bonding of alumina-phosphate (PAL) glass with cobalt-doped magnesium aluminate (MALO) crystals. The application of the hot embossing technique for bonding of PAL/MALO is a competitive method, as compared to the existing thermobonding techniques. The obtained PAL/MALO interfaces show high quality, similar to what is currently achievable with other, more expensive traditional methods. The interfaces of the bonded samples have been successfully tested for strength and damage thresholds. The damage threshold is estimated to be around 4.5 − 7.9 k W / c m 2 . Therefore, microlasers can be developed based on the obtained components.

Novel fiber microprobe comprising a nanostructured gradient index optical vortex phase mask and single-mode fiber was investigated numerically and experimentally. The mask which, consists of spatially distributed sub-wavelength nanorods, was fabricated via the modified stack-and-draw fiber drawing technique. The mask has flat input and output surfaces and transverse dimensions of a standard single-mode fiber. The microprobe allows efficient generation of high-quality optical vortex beams in different environments such as air and water.

A new type of ultrathin fiber microprobe for selective electroporation is reported. The microprobe is 10 cm long and has a diameter of 350 µm. This microprobe is a low cost tool, which allows electroporation of an arbitrary selected single cell or groups of cells among population with use of a standard microscope and cell culture plates. The microprobe in its basic form contains two metal microelectrodes made of a silver-copper alloy, running along the fiber, each with a diameter of 23 µm. The probe was tested in vitro on a population of normal and cancer cells. Successful targeted electroporation was observed by means of accumulation of trypan blue (TB) dye marker in the cell. The electroporation phenomenon was also verified with propidium iodide and Annexin V in fluorescent microscopy.

Development of high numerical aperture fiber bundles (FBs) requires use of thermally matched pair of glasses with a high difference of refractive indices. We have developed a pair of glasses with high refractive index contrast ΔnD>0.2, suitable for fabrication of optical fiber bundles with numerical aperture NA > 0.85. Core glass was synthetized in the lanthanum oxide system Nb2O5-Ta2O5-SiO2-ZrO2-B2O3-Al2O3-La2O3-BaO-SrO. Borosilicate glass synthetized in oxide system SiO2-Al2O3-B2O3-MgO-CaO-Na2O-K2O, thermally matched to the core glass, is used for the fiber cladding. The glasses also have high transmission from 350 to over 600 nm, which makes them ideal for fluorescence imaging applications. These thermally stable, crystallization-free lanthanum and borosilicate glasses have been successfully applied to development of proof-of-concept large diameter optical fiber.

The optical performance of nanostructured gradient index vortex phase masks (VPMs) in various external media was investigated. We utilized a modified stack-and-draw technique to fabricate the microscopic-size masks. Its structure contains spatially distributed sub-wavelength rods made of two thermally matched glasses with high and low refractive indices. Measured optical characteristics of the generated vortices with azimuthal phase distribution are presented. The numerical and experimental study shows that such VPMs with the same designed structure but varied thickness can convert fundamental light beam into optical vortices with different charges. Furthermore, we found that the mask performance is unaffected by the refractive index of the surrounding media making it an excellent candidate for microfluidic applications.

We report a development of microscopic size gradient index vortex masks using modified stack-and-draw technique. Vortex mask has a form of tens of microns thick, flat-surface all-glass plate. Its functionality is determined by internal nanostructure composed of two types of soft glass nanorods. Their spatial arrangement ensures that the average refractive index mimics continuous refractive index distribution imposing azimuthal phase modulation of optical beam. The mask of thickness of 40 microns is used to demonstrate generation of optical vortices with charges 1 and 2, in the femtosecond and cw regimes, respectively.

We present a novel method for the development of a micro lenslets hexagonal array. We use gradient index (GRIN) micro lenses where the variation of the refraction index is achieved with a structure of nanorods made of 2 types of glasses. To develop the GRIN micro lens array, we used a modified stack-and-draw technology which was originally applied for the fabrication of photonic crystal fibers. This approach results in a completely flat element that is easy to integrate with other optical components and can be effectively used in high refractive index medium as liquids. As a proof-of-concept of the method we present a hexagonal array of 469 GRIN micro lenses with a diameter of 20 µm each and 100% fill factor. The GRIN lens array is further used to build a Shack-Hartmann detector for measuring wavefront distortion. A 50 lens/mm sampling density is achieved.

We report the development of microscopic size gradient index vortex masks using the modified stack-and-draw technique. The vortex mask has a form of flat surface all-glass plate. Its functionality is determined by an internal nanostructure composed of two types of soft glass nanorods. The generation of optical vortices with charges 1 and 2 is demonstrated.

We study supercontinuum generation enhancement in an all-normal dispersion, all-glass photonic crystal fiber made of lead-silicate glasses. Dispersion characteristics were optimized through adjustment of regular hexagonal lattice of photonic crystal fiber in case of three different, thermally matched pairs of glasses. Supercontinuum generation was simulated with split-step Fourier method using the model that takes into account frequency-dependent effective mode area and losses, Raman response of the medium and temporal shape of the input pulse. An octave-spanning coherent supercontinuum has been obtained for all-glass fiber with lattice constant Λ = 1.73 μm and filling factor d/Λ = 0.8, made of silicate SF6/F2, spanning 850–2200 nm wavelengths in 10 dB dynamic range and pumped with pulses with energy as low as 3 nJ at 1550 nm.

We present a new type of gradient index fused silica fibre with nanostructured core. A gradient index core is obtained by means of arbitrary distribution of two types of subwavelength glass rods. The proposed method allows to obtain arbitrary gradient distribution not limited to a circular symmetry as in standard gradient index fibers. We have developed a proof of concept fibre and show a very good match between design and the measured properties of the fibre.

The phenomenon of laser light scattering provides the technology for visualization and testing the inner structure and homogeneity of materials. Some of them excited by the laser light in the tomographic process can emit light the wavelength of which is different than that of excitation laser. Such photoluminescence can be a source of additional information of the material’s structure. Combining the Laser Scattering Tomography (LST) and Spectrometry techniques has enabled us to develop a new type of an LST technique. The system is useful for investigations of various materials like semiconductors (Si, GaAs) ceramics, crystals for passive absorbers for high power pulse lasers, and laser crystals.

We report on our latest research in the field of nanostructured optical components fabricated using stack and draw technique. The concept of nanostructuring is based on the idea that the macroscopic optical properties of the system can be controlled by introduction of subwavelength elements. In some geometries even a single nanoinclusion can significantly change the performance of the device, in others incorporation of large amount of subwavelength elements justifies the usage of effective medium theory. Here, we demonstrate that nanostructurization through stack-and-draw method leads to development of fibres with carefully design birefringence and allows fabrication of elements of arbitrary effective index profiles. On the basis of Energy-dispersive X-ray spectroscopy measurements we also discuss the impact of selective diffusion process on optical properties of considered systems and show that this mechanism can be treated either as an opportunity to extend the dispersion engineering flexibility in optical elements or as a limitation which introduces the uncertainty of the final dispersion profile of the nanostructured components.

Development of photonic crystal fibers made of two or more types of glasses can be of considerable advantage in designing of specific properties of photonic crystal fibers. Replacing air holes with a medium with different refractive index provides an additional degree of freedom in fiber dispersion designing. Multi-component oxide glasses can be easily modified by changing the concentration of its ingredients, which in turn changes thermo-mechanical and optical properties of glass. In this paper, we discuss feasibility of joint thermal processing of two types of glasses for photonic crystal fiber drawing. Specifically, we optimize composition of our in-house synthesized high-alkaline borosilicate glass. A series of six- and seven-component glasses synthesized in $$\hbox {SiO}_{2}\hbox {--B}_{2}\hbox {O}_{3}\hbox {--Al}_{2}\hbox {O}_{3} \hbox {--(BaO)--Li}_{2}\hbox {O--Na}_{2}\hbox {O--K}_{2}\hbox {O}$$ oxide system was examined in experiments of combining with commercial lead-silicate glasses F2 and SF6. Joint thermal processing was validated by demonstration of successfully drawn structures of all-solid glass photonic crystal fibers. Critical glass parameters for thermal process of preform fabrication and subsequent fiber drawing, such as thermal expansion coefficient, characteristic viscosity temperatures and crystallization susceptibility were measured, and matched to F2 and SF6 glasses by optimizing composition of borosilicate glasses.

In this work we present the results of our research on luminescent properties in the visible spectral rangeof two different composite materials – based on polymer (PMMA) and glass (B 2 O 3 –BaO–K 2 O) hosts dopedwith Er 3+ +Yb 3+ :Y 2 O 3 nanocrystallites. The luminescent properties of these two composites were carefullystudied on the basis of excitation and emission characteristics complemented by fluorescence dynamicsprofiles. The specific attention was given to the main deactivation mechanisms and up-conversionphenomena as well as analysis of the influence of host’s type on the optical properties of erbium ions. 2014 Elsevier B.V. All rights reserved. 1. IntroductionComposite materials, which are a combination of two phaseswith different optical and mechanical properties – for example, aglass or polymer matrix with embedded active nanocrystallites –may potentially enable designing and development the entirelynew class of light sources, combining advantages of small size,low cost and improved optical and mechanical properties. Thespecific nature of composite media allows obtaining the resultantfeatures non-observable in classical materials, like e.g. efficientemission (and lasing) in the short-wavelength spectral range inhigh-phonon oxide glasses or polymers. This, in turn, significantlyextends the area of possible applications in integrated optoelec-tronics, imaging systems, sensor networks, etc.The idea of the optical composite material is not new – the firstvitroceramic composites (based on glasses doped with crystallinephase) were developed in the late sixties by G.H. Beall and D.A.Duke in the Corning Glass Research & Development Laboratories[1]. The first reports about two-phase optically active materialsfor laser applications are dated back to the beginning of the 70s[2,3], and the first publications on the short-wavelength emissionin vitroceramic materials appeared in 1975 [4]. It should be noted,however, that despite many years of research, light sources basedon vitroceramic materials never have been applied commercially,which partly results from a complex and expensive technology oftheir manufacturing.Polymer materials are manufactured in a much simpler andlow-cost processes, therefore they have been tested with respectof luminescent and lasing properties from the very beginning ofthe development of laser technology. The first reports of researchon active nanocrystallites doped with rare earth ions dispersed inliquid polymer matrix can be found in R.S. Meltzer works of 2001[5,6]. The work of J. W. Stouwdam team results in constructionof the planar amplifier based on PMMA doped with Nd

Introduction of subwavelength inclusions in the core opens up an additional degree of freedom in shaping of dispersion characteristic in photonic crystal fibers (PCFs). We have developed a PCF with a nanostructured inclusion in the core to verify this concept. To suppress higher order modes, the photonic cladding structure of the developed fiber is composed of a first ring with linear filling factor of 0.95 and the remaining 5 rings with a lower linear filling factor of 0.4 with a lattice constant of \(2.6\,\upmu \hbox {m}\). Diameter of the nano-inclusion in the core is 410 nm. For the fiber development, we used a pair of thermally matched soft glasses: Schott SF6 lead glass and an in-house synthesized NC21 borosilicate glass. In this paper, we report on dispersion measurements using a spectral interferomeric technique. A dispersion unbalanced Mach–Zehnder interferometer, combined with a supercontinuum source is used. Dispersion characteristics in wide range of wavelengths extending from 0.65 to \(1.6\,\upmu \hbox {m}\), are measured and verified against calculated results.

In this paper we report a two octave spanning supercontinuum generation in a bandwidth of 700–3000 nm in a single-mode photonic crystal fiber made of lead-bismuth-gallate glass. To our knowledge this is the broadest supercontinuum reported in heavy metal oxide glass based fibers. The fiber was fabricated using an in-house synthesized glass with optimized nonlinear, rheological and transmission properties in the range of 500–4800 nm. The photonic cladding consists of 8 rings of air holes. The fiber has a zero dispersion wavelength (ZDW) at 1460 nm. Its dispersion is determined mainly by the first ring of holes in the cladding with a relative hole size of 0.73. Relative hole size of the remaining seven rings is 0.54, which allows single mode performance of the fiber in the infrared range and reduces attenuation of the fundamental mode. The fiber is pumped into anomalous dispersion with 150 fs pulses at 1540 nm. Observed spectrum of 700–3000 nm was generated in 2 cm of fiber with pulse energy below 4 nJ. A flatness of 5 dB was observed in 950–2500 nm range.

Hot embossing is an attractive alternative to other micro-replication methods, since its cost effectiveness makes it suitable for mass-fabrication of wide range of elements. In this work, hot embossing is presented in context of fabrication of micro-optical elements made of soft glasses for near and mid infrared spectral region. Particular attention is given to the selection of suitable materials from which the mold is prepared, in order to minimize sticking and degradation of the embossing stamps. Refractive lens and diffractive gratings are successfully developed with the proposed approach.

On the basis of thermally bonded Er,Yb:glass/Co:MALO microchip a laser head pumped by fiber coupled laser diode was designed. The performance of the laser head were investigated and the main output parameters were determined. The energy over 40 μJ in 3.8 ns pulse with repetition rate of 0.735 kHz was achieved. The laser head characterized by such parameters can successfully be used in tele-detection applications.

We report on the design, fabrication, and experimental characterization of highly nonlinear tellurite glass photonic crystal fibers with engineered normal dispersion characteristics for coherent supercontinuum generation. Effectively single-mode air-hole lattice fibers with measured all-normal dispersion profiles as flat as −10 to −50 ps/mn/km over 1500–2400 nm wavelengths are developed and investigated. Supercontinuum spectra are measured for these fibers, with a spectral width covering 1100–2600 nm wavelengths under pumping with a robust fixed-wavelength erbium-fiber-based femtosecond laser, delivering 90 fs pulses, centered at 1560 nm with peak power below 40 kW. To the best of our knowledge, this is the first engineered microstructured fiber, which due to its high nonlinearity, enables a self-phase modulation and optical-wave-breaking-based supercontinuum pumped with a turn-key, 40 kW femtosecond laser at spectral widths obtainable with previous all-normal dispersion fiber designs only under pumping with systems delivering peak power in the megawatt range.

In this paper we report on the development of small-diameter lenses in soft glass with transmission in infrared till 5 μm using hot embossing method. A fused silica stamps and in-house synthesized tungsten–tellurium–niobate and lead–bismuth–galate glasses are used for replication. Optimization process of hot embossing is presented. Optical properties of replicated lenses were characterized. Resolution of 50 lp/mm is obtained.

Three component PbO–Bi2O3–Ga2O3 glasses are characterized by high midIR transmittance, with a large susceptibility to crystallization. In this paper we investigate the increase in the thermal stability of these glasses by the addition of oxides such as GeO2, SiO2, Tl2O, CdO, Nb2O5. The resulting multicomponent glasses are well suited for the fabrication of microstructured fibers and micro-optical elements. The increased thermal stability of the modified multi-component glasses resulted in the IR absorption cut-off shifting to shorter wavelengths.

We have developed a new type of an optical fiber probe which integrates the standard single mode fiber with a gradient index (GRIN) microlens. The system is perfectly suited for optofluidic sensor applications since the diameter of the lens module is exactly the same as the diameter of the optical fiber. Moreover, the performance of the GRIN lens is not degraded by low contrast of the refractive index between of the lens and the fluidic environment. The GRIN lens is made with novel technology of nanostructured optics. Full Text: PDF References M. Woerdemann, C. Alpmann, M. Esseling, C. Denz, "Advanced optical trapping by complex beam shaping", Laser Photonics Rev. 7, 839 (2013). CrossRef E. Weber, F. Keplinger, and M. J. Vellekoop, "On-Chip Light Modulation Applying Optofluidic Principles", IEEE Sensors Journal 13 4773 (2013). CrossRef F. Hudelist, J. M. Nowosielski, R. Buczynski, A. J. Waddie, M. R. Taghizadeh, "Nanostructured elliptical gradient-index microlenses", Optics Letters 35, 130 (2010) CrossRef J. M. Nowosielski, R. Buczynski, F. Hudelist, A. J. Waddie, M. R. Taghizadeh, "Nanostructured GRIN microlenses for Gaussian beam focusing", Opt. Comm. 283 1938 (2010). CrossRef A.Sihvola, Electromagnetic Mixing Formulas and Applications (London: The Institution of Electrical Engineers 1999). J. Nowosielski, R. Buczynski, A. J. Waddie, A. Filipkowski, D. Pysz, A. McCarthy, R. Stepien, M. R. Taghizadeh, "Large diameter nanostructured gradient index lens", Opt. Ex. 20 11767 (2012). CrossRef R. Stepien, J. Cimek, D. Pysz, I. Kujawa, M. Klimczak, R. Buczynski, "Soft glasses for photonic crystal fibers and microstructured optical components", Opt. Eng. 53, 071815 (2014). CrossRef A. Filipkowski, B. Piechal, D. Pysz, R. Stepien, A. Waddie, M. R. Taghizadeh, R. Buczynski, "Nanostructured gradient index microaxicons made by a modified stack and draw method", Opt. Lett. 40, 5200-5203 (2015). CrossRef

We present a dual mode, large core highly birefringent photonic crystal fiber with a photonic cladding composed of elliptical holes ordered in a rectangular lattice. The fiber is made of borosilicate glass and has a regular set of elliptical holes with an aspect ratio of 1.27 and a filling factor near 0.5. The group birefringence (G) and effective mode area were measured at 1550 nm for the fundamental mode and were found to equal 2 × 10−4 and 20 μm2 respectively. We discuss the influence of structural parameters including the ellipticity of the air holes and the aspect ratio of the rectangular lattice on the birefringence and on the fundamental and second modes of the fiber.

We report on modeling, development, and optical characterization of fused silica photonic crystal fiber with germanium doped microinclusion placed in the middle of the core. The fiber is designed to efficiently couple and guide LP02 mode. It offers high optical density in the center region, large mode separation, low losses, and small dispersion with relatively flat profile for both LP01 and LP02 modes in 1-1.6 µm wavelength range. We demonstrate that by changing geometrical and material parameters of the inclusion partially independent tuning of propagation constants of individual modes is possible, what might be found is a variety of potential applications, e.g., in nonlinear optics. We also show that diffraction-limited propagation of LP02 mode in free space can be exploited in microscopy or lab-on-a-chip systems, where the proposed fiber can be used for light delivery.

In this paper we report on ultra flat supercontinuum generation in dual core photonic crystal fiber pumped in the normal dispersion regime. The fiber cladding is fabricated from custom NC21 borosilicate glass while the fiber cores is made of commercially available F2 high index lead-silicate glass from Schott Corp. We investigated the supercontinuum characteristics for single and double core excitation by a Ti:Sapphire oscillator delivering 100 fs pulses centered at 800 nm with an energy of 4.2 nJ. Dual core pumping resulted in appreciable flattening of the supercontinuum spectra in the range 875 – 950 nm.

Most of the research work related to photonic crystal fibres has to date been focused on silica based fibres. Only in the recent years has there been a fraction of research devoted to fibres based on soft glasses, since some of them offer interesting properties as significantly higher nonlinearity than silica glass and wide transparency in the infrared range. On the other hand, attenuation in those glasses is usually one or more orders of magnitude higher that in silica glass, which limits their application area due to limited length of the fibres, which can be practically used. We report on the development of single-mode photonic crystal fibres made of highly nonlinear lead-bismuth-gallate glass with a zero dispersion wavelength at 1460 nm and flat anomalous dispersion. A two-octave spanning supercontinuum in the range 700–3000 nm was generated in 2 cm of the fibre. In contrast to the silica glass, various oxide based soft glasses with large refractive index difference can jointly undergo multiple thermal processing steps without degradation. The use of two soft glasses gives additional degrees of freedom in the design of photonic crystal fibres. As a result, highly nonlinear fibres with unique dispersion characteristics can be obtained. Soft glass allow also development of fibres with complex subwavelength refractive index distribution inside core of the fibre. A highly birefringent fibre with anisotropic core composed of subwavelength glass layers ordered in a rectangular structure was developed and is demonstrated

Nanostructured core photonic crystal fibers comprising a solid cladding and sub-wavelength layout of solid rods in the core are presented as a concept for radically new method for dispersion engineering in nonlinear fiber optics.

The nonlinear refractive index for 10 types of recently developed new soft glasses was measured under the same conditions using a pulsed Nd:YAG laser operating at 1064 nm with a 35 ps pulse duration. The study included various types of oxide-based soft glasses commonly used for nonlinear fiber optics, such as lead silicate, borosilicate, phosphatate, tellurite and heavy metal oxide glasses. All studied glasses have good rheological properties, and are suitable for further multi-step thermal processing, including fabrication of nonlinear photonic crystal fibers. As reference samples, standard fused silica glass and commercially available lead silicate glasses were used. The standard Z-scan setup was employed, with both “open-” and “closed-aperture” types of measurement. We show that nonlinearities of some benchmarked thermally stable heavy metal oxide glasses are comparable to more expensive and very fragile chalcogenide glasses.

We respond to the comment submitted by Xian Feng on our recent Letter, Opt. Lett.38, 4679 (2013). The comment addressed the attenuation of our oxide tellurite glass labeled TWPN/I/6. We provide the originally measured absorbance spectrum of the glass and correct values of its mid-infrared attenuation.