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(a) Induced phase retardation as a function of various processing conditions such as the azimuth density of the slow-axis rotation (□), pulse energy Ep (, insets), and numerical aperture (left to right: 0.16–1.2 NA). Blue open triangles (▿) show the relative standard deviation of the measured retardation value as a function of azimuth density of the slow-axis rotation. The azimuth density experiments were performed at a fixed pulse energy of 0.8 μJ for 0.16 NA, 0.35 NA, and 0.55 NA, and 0.4 μJ for 1.2 NA, and the pulse energy experiments were performed at a fixed azimuth density of 0.5 rad/μm. The retardance measurement system was operating at 546 nm wavelength. (b) Azimuth of the slow-axis of a laser induced form birefringence dependence on its rotation density. Top image—the azimuth of the slow-axis of the imprinted linear-phase element with the density varying from 0.05π rad/μm to 0.5π rad/μm; bottom graph—the profile (white dashed line in top image) of azimuth of the slow-axis extracted from the birefringence image. Pseudo colours (the inset in the top image) indicate the local orientation of the slow-axis. The birefringence measurement system was operating at 546 nm wavelength.
Source publication
High-precision three-dimensional ultrafast laser direct nanostructuring of silica glass resulting in multi-layered space-variant dielectric metasurfaces embedded in volume is demonstrated. Continuous phase profiles of nearly any optical component are achieved solely by the means of geometric phase. Complex designs of half-wave retarders with 90% tr...
Citations
... Recent emergence of directly written silica glass optical elements enabled a novel and elegant way to suppress output beam distortions and depolarization in end-pumped amplifiers. It was shown, that under high intensity laser irradiation, the structure of glass transforms into self-organized periodical nanostructures consisting of decomposed material planes [28,29]. Such self-structured pattern can then act as a birefringent material and introduce geometrical phase difference to incident laser radiation [29]. ...
... It was shown, that under high intensity laser irradiation, the structure of glass transforms into self-organized periodical nanostructures consisting of decomposed material planes [28,29]. Such self-structured pattern can then act as a birefringent material and introduce geometrical phase difference to incident laser radiation [29]. It is claimed that the nanostructures have a virtually unlimited lifetime and in order to measure any observable birefringence decay the temperature of the structure has to be increased to approximately 900 • C [30]. ...
... It is claimed that the nanostructures have a virtually unlimited lifetime and in order to measure any observable birefringence decay the temperature of the structure has to be increased to approximately 900 • C [30]. Therefore the technology, based on nanostructure inscription, allowed to produce a variety of optical phase-shifting elements that feature high laser induced damage threshold and good thermal stability [29,31]. In the case of optical amplifiers, the phase difference that is introduced to the beam in a thermally stressed active medium can be reproduced in a spatially variable waveplate (SVWP). ...
In this study we demonstrated a compact and cost-effective high energy and average power picosecond laser developed for OPCPA system pumping applications. The system delivered record high pulse energy at 100 W average power level in a hybrid laser architecture based on a fiber seed laser and free-space end-pumped Yb:YAG amplifiers. The output pulses were compressed to 1 ps pulse duration and the output beam featured M² = 1.3, which was further improved to 1.07 by spatial filtering. A silica glass spatially variable wave plate manufactured by direct laser writing was used to reduce depolarization losses from 12% to 5%.
... In this work, we use a type 2 modification of bulk transparent dielectric material to create a geometrical phase element (GPE) [53][54][55]. As a femtosecond laser beam is raster-scanned over the glass, nanogratings are formed with slow axes aligned perpendicular to the polarization of the laser beam. ...
In recent decades, significant progress has been made in the field of laser beam shaping, driven by the growing demands in both scientific research and industrial applications. Notably, a class of beams known as nondiffracting beams, which exhibit such characteristics as self-healing and resistance to diffraction, has found practical utility in communication, imaging, and laser microprocessing. Although Bessel beams have become commonplace for various optical applications, further advances in beam engineering remain a need. One of the key requirements is the ability to control the elongation of the transverse profile of an optical needle, which is highly sought after for specific applications. In this study, we propose to achieve this control by utilizing nondiffracting Airy beams. The elongation of the optical needle's transverse profile is achieved through the implementation of a binary phase mask. We evaluate the performance of this method through both numerical simulations and experimental assessments, employing various metrics, such as the major-to-minor axis ratio, the length of the optical needle, and its stability. We present a specific case where a flat optical element is created using geometrical phase induced by nanogratings inscribed within the element's volume by means of a femtosecond laser. We validate the performance of this geometrical phase element through laser microprocessing of transparent glasses and report the results obtained from these experiments.
... An adequate combination of (fs) laser parameters and glass composition enable the development of "on demand" glass-based photonic devices in both bulk and optical fiber forms. They include, for example, waveguides, couplers / splitters, optical data storage devices [1], micro-optics phase elements [2], optomechanics / optofluidics and integrated lab-on-chip photonic devices [3], or temperature / pressure / deformation sensors [4]. Several types of laser-induced modifications in silica / silicate glasses have been identified, including isotropic index change (Type I), birefringent self-organized nanogratings (NGs, Type II) [5,6,7,8], voids (Type III) [9], crystallization [10,11,12,13], and more recently elongated nanopores (Type X) [14]. ...
... Moreover, our research has provided insights into the formation of bulk nanogratings, revealing a self-adaptive near-field anisotropic nanostructuring process. These insights could inspire strategies to boost the formation of laser-induced structures across various fields, including optical data storage, [8] optical fiber sensors, [43] microfluidic, [44] micromechanics, [45] geometric phase elements, [46] photonic crystals, [47] and quantum mechanics. [48] ...
In the digital era, the need for high‐density data storage techniques has become increasingly imperative. To address this, the study has demonstrated a multi‐dimensional shingled optical recording technique, utilizing femtosecond laser‐induced nanostructures in silica glass. The evolution of the bulk nanostructures is investigated on a pulse‐by‐pulse basis using multiple microscopic analysis techniques. The formation of the nanostructures is attributed to a self‐adaptive near‐field anisotropic nanostructuring process. Furthermore, it is shown that writing in a 3D shingled configuration significantly reduces the volume per data voxel to a size of 500 nm × 500 nm × 1.0 µm, surpassing the diffraction limit. This reduction is achieved even when employing an infrared laser and a relatively low numerical aperture objective lens. As a result, the approach increases the data storage capacity by at least two orders of magnitude compared to conventional techniques. The work paves the way for advanced shingled optical recording techniques offering ultra‐dense capacity, ultra‐long lifetime, and low energy consumption.
... In this work, we use a type 2 modification of bulk transparent dielectric material to create a geometrical phase element (GPE) [53][54][55]. As a femtosecond laser beam is raster-scanned over the glass, nanogratings are formed with slow axes aligned perpendicular to the polarization of the laser beam. ...
... Self-assembled nanogratings (NGs), fabricated inside transparent materials such as glasses, have found interest in many fields of optics, including optical data storage, harsh environment temperature and pressure sensing, structural health monitoring, 3D space variant birefringent devices, optofluidics, optomechanics, and integrated optics [1][2][3][4][5]. These NGs, also labeled Type II regime in the literature, are typically made of pseudo-periodic porous nanolayers containing nanopores or nanocavities. ...
The thermal stability of self-assembled porous nanogratings inscribed by an infrared femtosecond (fs) laser in five commercial glasses (BK7, soda lime, 7059, AF32, and Eagle XG) is monitored using step isochronal annealing experiments. Their erasure, ascertained by retardance measurements and attributed to the collapse of nanopores, is well predicted from the Rayleigh–Plesset (R–P) equation. This finding is thus employed to theoretically predict the erasure of nanogratings in the context of any time–temperature process (e.g., thermal annealing, laser irradiation process). For example, in silica glass (Suprasil CG) and using a simplified form of the R–P equation, nanogratings composed of 50 nm will erase within ${\sim}{30}\;{\rm min}$ ∼ 30 m i n , ${\sim}{1}\;{\unicode{x00B5}}{\rm s}$ ∼ 1 µ s , and ${\sim}{30}\;{\rm ns}$ ∼ 30 n s at temperatures of ${\sim}{1250}^\circ{\rm C}$ ∼ 1250 ∘ C , 2675°C, and 3100°C, respectively. Such conclusions are expected to provide guidelines to imprint nanogratings in oxide glasses (for instance, in the choice of laser parameters) or to design appropriate thermal annealing protocols for temperature sensing.
... In recent decades, femtosecond laser micromachining has attracted extensive research interest due to its ability to fabricate various 3D structures with varied functions in transparent materials with a wide range of applications [1][2][3][4][5][6]. Compared with the surface micro-nano structure, the micro-nano structure inside the transparent materials shows abrasion resistance, heat resistance, erasability, polarizationdependent, and physicochemical anisotropy [7][8][9][10]. Micro-nano gratings have been utilized in integrated optics for their advantageous features, such as metasurfaces [9], phase elements [7,8,11], light attenuators [4,12], and data storage [13][14][15]. ...
... Compared with the surface micro-nano structure, the micro-nano structure inside the transparent materials shows abrasion resistance, heat resistance, erasability, polarizationdependent, and physicochemical anisotropy [7][8][9][10]. Micro-nano gratings have been utilized in integrated optics for their advantageous features, such as metasurfaces [9], phase elements [7,8,11], light attenuators [4,12], and data storage [13][14][15]. The majority of the publications, however, reported that the morphology of micro-nano gratings is polarized-dependent, that the period of the micro-nano gratings can only be changed in a limited range, and even that several reports have demonstrated controlling the micro-nano gratings using femtosecond laser shaping [16,17]. ...
... They can be fabricated with liquid-crystal materials 10 or with metamaterials. 11 Geometric phase polarization diffraction gratings (PDG) are commercially available nowadays. ...
... This approach offers flexibility in producing VV beams but the method is highly sensitive to external vibrations. Other techniques include the use of q-plates, and S-wave-plates [20][21][22] www.nature.com/scientificreports/ be fabricated with liquid-crystal technology or as metasurfaces. ...
A liquid crystal Spatial Light Modulator (SLM) can be used in various ways to produce vector-vortices. Superposition of scalar vortices with orthogonal polarization is a common approach, while a more recent technique is to use dual-phase modulation. These approaches require modulation of at least two phase patterns with a SLM or multiple SLMs. In this paper, we propose a novel technique to produce vector-vortices by modulating orthogonal light components through a single phase pattern with a SLM. It does not require interferometric setups, and simplifies the generation of light beams with V-point polarization singularities. Because of compact and robustness of our experimental setup, it can be easily integrated to any device for applications of vector-vortices.
... С помощью контроля ориентации записываемых структур [14], направление которых перпендикулярно поляризации используемого при записи лазерного излучения, возможно создание разнообразных оптических элементов [1,6,15,16]. Как материал плавленый кварц представляет интерес для различных прикладных задач из-за широкого диапазона пропускания, высокого порога оптического пробоя и умеренной дисперсии показателя преломления. ...
... Однако создаваемые структуры не всегда обладают высоким пропусканием, необходимым для прикладных задач. Это может быть связано с флуктуацией периодичности записываемых структур и может быть исправлено увеличением числа импульсов в точку в процессе записи структур при более низкой скорости сканирования или перемещения образца, что приведет к образованию более однородных структур [16]. Также потери пропускания можно уменьшить с помощью уменьшения размера элементов записываемых структур. ...
The writing process of birefringent structures in the volume of fused silica by focused ultrashort laser pulses with wavelength in visible range and various values of pulse energy, pulse duration, repetition rate, numerical aperture and moving substrate velocity has been studied. The retardance value of fabricated structures has been measured and influence of the subsequent annealing of these structures has been studied. It was shown, that combination of writing layered structures with subsequent annealing provides structures with high homogeneity, required retardance value and high transmittance.
