Showing papers on "Birefringence published in 2022"
70 citations
TL;DR: In this paper , the authors review the developments of emergent candidates with the experimentally measured birefringence ≥ 0.1 in the field of optical materials and discuss the relationship between the crystal structures and bireringence.
63 citations
TL;DR: In this article , a two coupled nonlinear Schrödinger equation (CNLSE) which is applicable to high birefringence fibers is investigated and a variety of bright and dark optical envelope soliton solutions are derived.
46 citations
TL;DR: In this paper , a new fluoroborophosphate (NH4)3B11PO19F3 (ABPF) was reported, which exhibits a KBBF-like structure while eliminating the limitations of KBBF crystal.
Abstract: Abstract Deep-ultraviolet (DUV) nonlinear optical (NLO) crystals that can extend the output range of coherent light below 200 nm are pivotal materials for solid-state lasers. To date, KBe2BO3F2 (KBBF) is the only usable crystal that can generate DUV coherent light by direct second harmonic generation (SHG), but the layered growth habit and toxic ingredients limit its application. Herein, we report a new fluoroborophosphate, (NH4)3B11PO19F3 (ABPF), containing four different functional units: [BO3], [BO4], [BO3F] and [PO4]. ABPF exhibits a KBBF-like structure while eliminating the limitations of KBBF crystal. The unique [B5PO10F]∞ layers enhance ABPF’s performance; for example, it has a large SHG response (1.2 × KDP) and a sufficient birefringence (0.088 at 1064 nm) that enables the shortest phase-matching wavelength to reach the DUV region. Meanwhile, the introduction of strong B-O-P covalent bonds decreases the layered growth habit. These findings will enrich the structural chemistry of fluoroborophosphate and contribute to the discovery of more excellent DUV NLO crystals.
42 citations
04 Jan 2022
TL;DR: Detailed theoretical calculations confirm that the employment of highly polarizable Hg2+ is an effective strategy to design superior optical materials with large birefringence and strong SHG response.
Abstract: Discovering novel sulfate optical materials with strong second-harmonic generation (SHG) and large birefringence is confronted with a great challenge attributed to the intrinsically weak polarizability and optical anisotropy of tetrahedral SO4 groups. Herein, two superior-performing sulfate optical materials, namely, noncentrosymmetric Hg3O2SO4 and centrosymmetric CsHgClSO4·H2O, have been successfully synthesized through the introduction of a highly polarizable d10 metal cation, Hg2+. The unique component layers in the reported compounds, [Hg3O2SO4]∞ layers in Hg3O2SO4 and [HgClSO4(H2O)] [[EQUATION]] layers in CsHgClSO4·H2O, induce enlarged birefringence in each sulfate. Remarkably, Hg3O2SO4 exhibits a very large SHG response of 14.0 times that of KH2PO4, which is the strongest efficiency among all the reported nonlinear optical sulfates. Detailed theoretical calculations confirm that the employment of highly polarizable Hg2+ is an effective strategy to design superior optical materials with large birefringence and strong SHG response.
41 citations
TL;DR: LiBO2 as discussed by the authors is a birefringent crystal based on [BO2]∞ infinite chains in the Li-B-O system, which simultaneously achieves the shortest UV cutoff edge (164 nm).
Abstract: Birefringent materials play indispensable roles in modulating the polarization of light and are vital in the laser science and technology. Currently, the design of birefringent materials operating in the deep-ultraviolet region (DUV, λ ≤200 nm) is still a great challenge. In this work, we developed a new DUV birefringent crystal LiBO2 based on [BO2]∞ infinite chains in the Li-B-O system, which simultaneously achieves the shortest UV cutoff edge (164 nm) and the largest birefringence (≥0.168 at 266 nm) among all the reported borate-based DUV birefringent materials. Single crystals of LiBO2 with dimensions up to Ø55 × 34 mm3 were grown by the Czochralski method, providing access to large-sized single crystal with low cost. Moreover, it has a high laser damage threshold and stable physicochemical properties. These outstanding characters unambiguously support that LiBO2 can be an excellent birefringent material for DUV application.
40 citations
TL;DR: In this paper , the authors proposed a method for increasing the birefringence of borophosphates and pushing phase-matching into the short-wavelength region.
Abstract: Borophosphates are very known for the short ultraviolet (UV) cutoff edge and have become the promising UV and deep-UV functional crystals candidates; however, tetrahedral [PO4] and [BO4] groups own weak anisotropy of polarizability and are not conducive to large birefringence, which hinders their application in the short-wavelength region. Improving their birefringence without compromising the band gap is the main research objective. By introducing the excellent birefringent functional groups, such as [B2O5], [BO2]∞ chain, [B2Ox(OH)5-x], and so forth into borophosphates, seven borophosphates with improved birefringence were successfully synthesized (Δn > 0.05@532 nm). Remarkably, among them, the centimeter-sized crystal of Rb3B8PO16 with a short deep-UV cutoff edge (175 nm) and large birefringence (Δn(exp.) ∼ 0.072@589.3 nm) exhibits the shortest phase-matching wavelength (222 nm), which makes Rb3B8PO16 a promising UV NLO crystal, while KB6PO10(OH)4 with deep-UV cutoff edge features the largest birefringence (Δn(exp.) ∼ 0.103@546 nm) in the reported borophosphate system, making KB6PO10(OH)4 a promising deep-UV birefringent crystal. This study not only provides feasible strategies for increasing the birefringence of borophosphates but also pushes phase-matching into the short-wavelength region.
39 citations
TL;DR: LiBO2 as discussed by the authors is a birefringent crystal based on [BO2]∞ infinite chains in the Li-B-O system, which simultaneously achieves the shortest UV cutoff edge (164 nm).
Abstract: Birefringent materials play indispensable roles in modulating the polarization of light and are vital in the laser science and technology. Currently, the design of birefringent materials operating in the deep-ultraviolet region (DUV, λ ≤200 nm) is still a great challenge. In this work, we developed a new DUV birefringent crystal LiBO2 based on [BO2]∞ infinite chains in the Li-B-O system, which simultaneously achieves the shortest UV cutoff edge (164 nm) and the largest birefringence (≥0.168 at 266 nm) among all the reported borate-based DUV birefringent materials. Single crystals of LiBO2 with dimensions up to Ø55 × 34 mm3 were grown by the Czochralski method, providing access to large-sized single crystal with low cost. Moreover, it has a high laser damage threshold and stable physicochemical properties. These outstanding characters unambiguously support that LiBO2 can be an excellent birefringent material for DUV application.
38 citations
TL;DR: In this paper , the authors search for the signature of parity-violating physics in the cosmic microwave background, called cosmic birefringence, using the Planck data release 4.
Abstract: We search for the signature of parity-violating physics in the cosmic microwave background, called cosmic birefringence, using the Planck data release 4. We initially find a birefringence angle of $\beta=0.30\pm0.11$ (68% C.L.) for nearly full-sky data. The values of $\beta$ decrease as we enlarge the Galactic mask, which can be interpreted as the effect of polarized foreground emission. Two independent ways to model this effect are used to mitigate the systematic impact on $\beta$ for different sky fractions. We choose not to assign cosmological significance to the measured value of $\beta$ until we improve our knowledge of the foreground polarization.
35 citations
10 May 2022
TL;DR: In this paper , a double-modification strategy driven by F and OH anions that makes double effects towards the critical property enhancement of deep-UV birefringent crystals is proposed.
Abstract: Polarization modulation of deep-UV light is of great significance to the current technologies, and to this end, birefringent crystal has emerged as an invaluable material as it allows for the effective light modulation. Herein, double-modification strategy driven by F and OH anions that makes double effects towards the critical property enhancement of deep-UV birefringent crystals is proposed. This leads to the discovery of a new hydroxyborate (NH 4 ) 4 [B 12 O 16 F 4 (OH) 4 ] with unprecedented giant cluster as a deep-UV birefringent crystal with large birefringence (Δ n exp. = 0.12@546 nm). Such a birefringence sets a record among inorganic hydroxyborates with experimentally measured birefringence. The [B 12 O 16 F 4 (OH) 4 ] cluster in near-plane arrangement is enabled by the hydrogen-bonding interactions; and it is theoretically confirmed to be optical-active for large birefringence and band gap, in which the π-conjugated modules, [BO 3 ] and [BO 2 (OH)], are the main sources of large optical anisotropy.
35 citations
TL;DR: In this paper , the propagation of ultrashort light pulses in a birefringent optical fiber exhibiting spatiotemporal dispersion, cross-and self-phase modulation, self-steepening and group-velocity dispersion effects is addressed.
Abstract: The propagation of ultrashort light pulses in a birefringent optical fiber exhibiting spatiotemporal dispersion, cross- and self-phase modulation, self-steepening, and group-velocity dispersion effects is addressed. The evolution of light pulses in such system is described by the coupled Fokas-Lenells equations which offer an accurate description of pulse dynamics in the femtosecond range when certain terms of the next asymptotic order beyond those necessary for the nonlinear Schrödinger equation are sustained. We report the first analytical demonstration of the propagation of chirped solitons in a birefringent fiber medium governed by the coupled Fokas-Lenells equations. The formation of those nonlinearly chirped solitons in the optical material may be attributed to the presence of self-steepening process. The results show that the frequency chirp associated with each of the two field components is directly proportional to the total intensity of the pulse. The chirped solitons for the system including the dark-dark and bright-bright soliton pairs in the presence of all fiber parameters are retrieved. The chirps accompanying the soliton pairs are also determined. The existence constraints of these chirped solitons are presented. In addition, the stability of the chirped solutions with respect to the finite perturbations is studied numerically.
TL;DR: In this paper , a thorough review on the recent achievements of metal oxyhalides for NLO materials are divided into the fast-growing NLO metal oxy-halides with single type halogen anions and the newly identified NLO metamaterials with mixed halogenanions.
Abstract: Second-order nonlinear optical (NLO) materials have drawn enormous academic and technological attention attributable to their indispensable role in laser frequency conversion and other greatly facilitated applications. The exploration of new NLO materials with high performances thus has long been an intriguing research field for chemists and material scientists. However, an ideal NLO material should simultaneously satisfy quite a few fundamental yet rigorous criteria including a noncentrosymmetric structure, large NLO coefficients, desired transparent range, large birefringence, high laser damage threshold, and availability of a large-size single crystal. Therefore, the identification of promising compound systems, targeted design, and experience-based syntheses are crucial to discover novel NLO materials working in the spectral region of interest. As an important family of mixed-anion compounds, versatile metal oxyhalides containing metal-centered oxyhalide functional units ([MOmXn] (X = F, Cl, Br, and I)) are becoming a marvelous branch for interesting NLO materials. Especially, when the central metals are d0/d10 transition metals or heavy post-transition metals, a number of novel NLO materials with superior functionalities are expected. Our thorough review on the recent achievements of metal oxyhalides for NLO materials are divided into the fast-growing NLO metal oxyhalides with single type halogen anions and the newly identified NLO metal oxyhalides with mixed halogen anions. Here we mainly focus on the design strategy, structural chemistry, NLO-related properties, and structure–property correlation of the metal oxyhalides with relatively large NLO responses. We hope this review can provide an insight on the rational design and future development of emerging metal oxyhalides for NLO and other applications.
20 Jan 2022
TL;DR: In this paper , a fluorinated tetrahedral boron-centred chromophore strategy was proposed to optimize the chromatic dispersion for phase-matching (PM).
Abstract: Exploring significant ultraviolet/deep-ultraviolet nonlinear optical (NLO) materials is hindered by rigorous and contradictory requirements, especially, possessing a moderate optical birefringence to meet phase-matching (PM). Except for suitable birefringence, small chromatic dispersion is also crucial to blue-shift the PM wavelength. Here, the introduction of a fluorinated tetrahedral boron-centred chromophore strategy was proposed to optimize the chromatic dispersion. Herein, the [BF4 ]- unit with a large HOMO-LUMO band gap was introduced to the Na-B-O-F system and Na4 B8 O9 F10 was designed and synthesized successfully for the first time. Na4 B8 O9 F10 with an optimized chromatic dispersion can achieve a short second harmonic generation PM wavelength of 240 nm with a relatively small birefringence (0.036@1064 nm). Notably, Na4 B8 O9 F10 is the first acentric crystal with [BF4 ]- units among the reported metal-fluorooxoborate systems, involving isolated [BF4 ]- and novel [B7 O10 F6 ]5- fundamental building blocks.
TL;DR: In this paper , the frequency dependence of the cosmic birefringence angle from the Planck Data Release 4 polariza- tion maps has been studied and a power law formula has been proposed for the BER.
Abstract: We present new constraints on the frequency dependence of the cosmic birefringence angle from the Planck Data Release 4 polariza- tion maps. An axion field coupled to electromagnetism predicts a nearly frequency-independent birefringence angle, β ν = β , while Faraday rotation from local magnetic fields and Lorentz violating theories predict a cosmic birefringence angle that is proportional to the frequency, ν , to the power of some integer n , β ν ∝ ν n . In this work, we first sampled β ν individually for each polarized HFI frequency band in addition to the 70GHz channel from the LFI. We also constrained a power law formula for the birefringence angle, β ν = β 0 ( ν/ν 0 ) n , with ν 0 = 150GHz. For a nearly full-sky measurement, f sky = 0 . 93, we find β 0 = 0 . 26 ◦ ± 0 . 11 ◦ (68% C.L.) and n = − 0 . 45 + 0 . 61 − 0 . 82 when we ignore the intrinsic EB correlations of the polarized foreground emission, and β 0 = 0 . 33 ◦ ± 0 . 12 ◦ and n = − 0 . 37 + 0 . 49 − 0 . 64 when we use a filamentary dust model for the foreground EB . Next, we used all the polarized Planck maps, including the 30 and 44GHz frequency bands. These bands have a negligible foreground contribution from polarized dust emission and we thus treated them separately. Without any modeling of the intrinsic EB of the foreground, we generally find that the inclusion of the 30 and 44GHz frequency bands raises the measured values of β ν and tightens n . At nearly full-sky, we measure β 0 = 0 . 29 ◦ + 0 . 10 ◦ − 0 . 11 ◦ and n = − 0 . 35 + 0 . 48 − 0 . 47 . Assuming no frequency dependence, we measure β = 0 . 33 ◦ ± 0 . 10 ◦ . If our measurements have e ff ectively mitigated the EB of the foreground, our constraints are consistent with a mostly frequency-independent signal of cosmic birefringence.
TL;DR: In this paper , the authors demonstrate near-chirp-free solitons with distinct spectral sidebands in normal-dispersion hybrid-structure fiber lasers containing a few meters of polarization-maintaining fiber.
Abstract: Abstract Direct generation of chirp-free solitons without external compression in normal-dispersion fiber lasers is a long-term challenge in ultrafast optics. We demonstrate near-chirp-free solitons with distinct spectral sidebands in normal-dispersion hybrid-structure fiber lasers containing a few meters of polarization-maintaining fiber. The bandwidth and duration of the typical mode-locked pulse are 0.74 nm and 1.95 ps, respectively, giving the time-bandwidth product of 0.41 and confirming the near-chirp-free property. Numerical results and theoretical analyses fully reproduce and interpret the experimental observations, and show that the fiber birefringence, normal-dispersion, and nonlinear effect follow a phase-matching principle, enabling the formation of the near-chirp-free soliton. Specifically, the phase-matching effect confines the spectrum broadened by self-phase modulation and the saturable absorption effect slims the pulse stretched by normal dispersion. Such pulse is termed as birefringence-managed soliton because its two orthogonal-polarized components propagate in an unsymmetrical “X” manner inside the polarization-maintaining fiber, partially compensating the group delay difference induced by the chromatic dispersion and resulting in the self-consistent evolution. The property and formation mechanism of birefringence-managed soliton fundamentally differ from other types of pulses in mode-locked fiber lasers, which will open new research branches in laser physics, soliton mathematics, and their related applications.
TL;DR: In this paper , a surface plasmon resonance (SPR) sensor based on a D-shaped germanium-doped photonic crystal fiber (PCF) is proposed.
Abstract: In this work, a surface plasmon resonance (SPR) sensor based on a D-shaped germanium-doped photonic crystal fiber (PCF) is proposed. The finite element method (FEM) is introduced to analyze the structure parameters, such as germanium-doped concentration, lattice pitch, and air hole size. In addition, the coupling properties and birefringence properties of PCF are also studied. The computer simulation results indicate that two different surface plasmon polariton (SPP) coupling modes are produced on the polished surface, covered with metal film, when the analyte refractive index (RI) is 1.34. Then, with the increase of the RI, the incompleteness of one of the coupling modes will be transformed into the complete coupling. The effect of germanium concentration on the birefringence is also analyzed. It has an optimal wavelength sensitivity of 5600 nm/RIU when the RI is 1.37. This sensor exhibits a maximum birefringence of 1.06 × 10−2 and a resolution of 1.78 × 10−5 RIU with high linearity.
TL;DR: In this article , a series of melilite-type oxide-derived non-centrosymmetric (NCS) oxychalcogenides, Sr2MGe2OS6 (M = Mn, Zn, and Cd), were successfully designed and synthesized through a facile partial isovalent chemical substitution strategy.
Abstract: Simultaneous regulation and control of non-linear second-harmonic-generation (SHG) coefficients (deff) and linear birefringence (Δn) of non-centrosymmetric (NCS) crystals is a crucial aspect of improving the non-linear optical (NLO) performance, yet it remains a huge challenge in modern laser techniques and science. Herein, a series of melilite-type oxide-derived NCS oxychalcogenides, Sr2MGe2OS6 (M = Mn, Zn, and Cd), are successfully designed and synthesized through a facile partial isovalent chemical substitution strategy. These isostructural compounds crystallize in the tetragonal NCS space group P4̅21m (no. 113) and feature unique two-dimensional Cairo pentagonal tiling layers composed of heteroligand [GeOS3] and tetrahedral [MS4] asymmetric building units (ABUs). Compared to the parent melilite-type oxides, the derived title compounds not only successfully realize the phase matchability transformation [i.e., from non-phase-matching (NPM) to phase-matching (PM)] but also greatly improve the IR-NLO performance (especially, simultaneously boosting deff and Δn). Sr2CdGe2OS6 exhibits the best comprehensive performance among oxychalcogenides, including a wide PM cutoff edge (>525 nm), a strong deff (0.8 × AgGaS2), a giant laser-induced damage threshold (19.2 × AgGaS2), a large band gap (3.62 eV), as well as a broad transmission cutoff region (0.28–12.0 μm). Furthermore, highly distorted [GeOS3] ABU in this melilite-type structure is proved to be the profitable bifunctional NLO-active unit, which can contribute to the search and design of novel IR-NLO crystals with a large Δn and a strong deff based on the experimental results and theoretical calculations. This work demonstrates the first examples of PM melilite-type oxychalcogenides and offers new perspectives on the phase matchability transformation through the partial isovalent chemical substitution approach, which will play a constructive role in the future design of high-performance IR-NLO heteroanionic materials.
TL;DR: In this article , the authors proposed hydroxylated π-conjugated [B(OH)3] and [B3O3(OH)-3] units for designing DUV birefringent materials.
Abstract: Birefringent materials play a significant role to modulate polarized light in optical communication and the laser industry. However, the discovery of deep ultraviolet (DUV, λ < 200 nm) birefringent materials still faces a serious challenge. Herein, we propose hydroxylated π-conjugated [B(OH)3] and [B3O3(OH)3] units for designing DUV birefringent materials. Innovatively, four new hydroxyborates have been synthesized under mild synthesis conditions. They present four novel pseudo layers that benefit from a large degree of freedom assembly modes of [B(OH)3] and [B3O3(OH)3] genes and large birefringence (0.057-0.123@532 nm). Moreover, The Cs3[B(OH)3]2Cl3 crystal features a short DUV cutoff edge (180 nm), which further indicates that reported compounds are potential DUV birefringent crystals. Free and flexible assembly modes of π-conjugated [B(OH)3] and [B3O3(OH)3] groups endow them a particular advantage as significant genes for exploring promising DUV birefringent materials.
TL;DR: In this article, the latest development of fiber-optic structures based on refractive index (RI) modification under fs-laser irradiation and their applications are reviewed. And then, the performances of RI-modified structures and their application are presented and compared.
Abstract: Femtosecond (fs) laser pulses direct writing technology has been extensively employed to achieve microfabrication in various optical fibers for a broad range of applications. In this paper, the latest development of fiber-optic structures based on refractive index (RI) modification under fs-laser irradiation and their applications are reviewed. Firstly, the processing mechanism of fs-laser direct writing for optical fiber RI modification is described. And then, the fiber-optic structures including various fiber gratings and interferometers based on RI modification are summarized. It shows that the fs-laser direct writing technology has great advantages in the fabrication of various fiber structures with excellent properties. Furthermore, the applications of these RI-modified fiber-optic structures in sensors, lasers, birefringence adjustable elements, and couplers are also discussed. To conclude, the performances of RI-modified structures and their applications are presented and compared.
TL;DR: In this paper , a bi-thickness semi-tube ARF structure with fourfold rotational symmetry was designed, and the first ARF with a level of birefringence close to 10−4 was fabricated.
Abstract: The optical performance characteristics of anti‐resonant hollow‐core fibers (known as AR‐HCFs or ARFs) are improving rapidly, but the polarization maintaining issue with these fibers remains unresolved. Although a regular nonbirefringent ARF can maintain high polarization purity under static conditions, it cannot resist mechanical disturbances. In this work, by designing a bi‐thickness semi‐tube ARF structure with fourfold rotational symmetry, the first ARF with a level of birefringence close to 10−4 is fabricated. The proposed ARF features a combination of phase birefringence of 9.1 × 10−5, a minimum loss of 185 dB km−1, a bandwidth of 133 nm, and single‐mode operation. Furthermore, the ARF shows high resistance to fiber bending and wide‐range temperature variations, thus confirming that this carefully designed ARF can serve as a practical workhorse in polarization‐related optical fiber applications.
01 Aug 2022
TL;DR: In this article , the authors focused on the dynamical behavior and dispersive optical solitons in birefringent fibers with coupled Schrödinger-Hirota equation.
Abstract: The main attention of this paper focuses on the dynamical behavior and dispersive optical solitons in birefringent fibers with coupled Schrödinger-Hirota equation. Under the traveling wave transformations, the coupled Schrödinger-Hirota equation is reduced to plane dynamical system. With the help of the theory of planar dynamical system, we obtain a range of solutions which contain bell-shaped wave solutions, periodic wave solutions and kink-shaped wave solutions. Then by using the complete discriminant system method and symbolic computation, we give all the classification of single traveling wave solutions for the coupled nonlinear Schrödinger-Hirota equation. It is notable that the obtained results substantially improve or complement the corresponding conditions in the references [19, 20]. As a consequence, this paper gives a new idea to construct dispersive optical solitions for the coupled Schrödinger-Hirota equation.
TL;DR: In this paper , reflective MEMS-OMS dynamic wave plates (DWPs) with high polarization conversion efficiencies (∼75%), broadband operation, and full-range birefringence control that enables completely enclosing the Poincaré sphere along trajectories determined by the incident light polarization and DWP orientation.
Abstract: Dynamic polarization control is crucial for emerging highly integrated photonic systems with diverse metasurfaces being explored for its realization, but efficient, fast, and broadband operation remains a cumbersome challenge. While efficient optical metasurfaces (OMSs) involving liquid crystals suffer from inherently slow responses, other OMS realizations are limited either in the operating wavelength range (due to resonances involved) or in the range of birefringence tuning. Capitalizing on our development of piezoelectric micro-electro-mechanical system (MEMS) based dynamic OMSs, we demonstrate reflective MEMS-OMS dynamic wave plates (DWPs) with high polarization conversion efficiencies (∼75%), broadband operation (∼100 nm near the operating wavelength of 800 nm), fast responses (<0.4 milliseconds) and full-range birefringence control that enables completely encircling the Poincaré sphere along trajectories determined by the incident light polarization and DWP orientation. Demonstrated complete electrical control over light polarization opens new avenues in further integration and miniaturization of optical networks and systems.
TL;DR: In this paper , the authors demonstrate near-chirp-free solitons with distinct spectral sidebands in normal-dispersion hybrid-structure fiber lasers containing a few meters of polarization-maintaining fiber.
Abstract: Abstract Direct generation of chirp-free solitons without external compression in normal-dispersion fiber lasers is a long-term challenge in ultrafast optics. We demonstrate near-chirp-free solitons with distinct spectral sidebands in normal-dispersion hybrid-structure fiber lasers containing a few meters of polarization-maintaining fiber. The bandwidth and duration of the typical mode-locked pulse are 0.74 nm and 1.95 ps, respectively, giving the time-bandwidth product of 0.41 and confirming the near-chirp-free property. Numerical results and theoretical analyses fully reproduce and interpret the experimental observations, and show that the fiber birefringence, normal-dispersion, and nonlinear effect follow a phase-matching principle, enabling the formation of the near-chirp-free soliton. Specifically, the phase-matching effect confines the spectrum broadened by self-phase modulation and the saturable absorption effect slims the pulse stretched by normal dispersion. Such pulse is termed as birefringence-managed soliton because its two orthogonal-polarized components propagate in an unsymmetrical “X” manner inside the polarization-maintaining fiber, partially compensating the group delay difference induced by the chromatic dispersion and resulting in the self-consistent evolution. The property and formation mechanism of birefringence-managed soliton fundamentally differ from other types of pulses in mode-locked fiber lasers, which will open new research branches in laser physics, soliton mathematics, and their related applications.
TL;DR: In this article , femtosecondlaser-induced anisotropic nanopore structures (type X modification) in silica glass are used for optical data storage with high capacity and ultralong lifetime.
Abstract: The demand for energy efficient data storage technologies with high capacity and long life span is increasingly growing due to the explosion of digital information in modern society. Here, a 5D optical data storage with high capacity and ultralong lifetime is realized by femtosecond‐laser‐induced anisotropic nanopore structures (type X modification) in silica glass. The ultrahigh transmission of this birefringent modification, >99% in the visible range, allows recording and retrieving thousands of layers of multibit digital data practically. Type X formation is associated with moderate free carrier density produced close to the energy threshold of avalanche ionization. Higher retardance with increased repetition rate at low pulse energy is attributed to accumulation of defects (nonbridging oxygen hole centers), enabling rapid imprinting of voxels by megahertz‐rate pulses. Data recording of 7 bits per voxel, i.e., 25 azimuth angles and 22 retardance levels is experimentally demonstrated with readout error as small as 0.6%. Furthermore, “The Hitchhiker's Guide to the Galaxy” by Douglas Adams is optically recorded with a data writing speed of 8 kB s−1 in 100 layers of voxels and the proven data readout accuracy of 100%.
TL;DR: In this paper , the polar covalent tetrahedron [SO 2 (NH 2 ) 2 ] was revealed as a new deep-ultraviolet (DUV) nonlinear optical (NLO)-active unit according to the theoretical calculations.
Abstract: For the first time, the polar covalent tetrahedron [SO 2 (NH 2 ) 2 ] was revealed as a new deep-ultraviolet (DUV) nonlinear optical (NLO)-active unit according to the theoretical calculations. Furthermore, sulfamide consisting of the polar [SO 2 (NH 2 ) 2 ] units was confirmed as an excellent DUV NLO material. Since sulfamide realizes the optimal balance in the relationships among composition, structure, and properties, in addition to very short absorption of 160 nm, it achieves multiple optical performance records among the non-π-conjugated DUV NLO materials, including the strongest SHG efficiency (about 4 times that of KDP), the largest birefringence (obv.: 0.07@589.3 nm) and the shortest SHG wavelength predicted as 188 nm. Therefore, sulfamide should be a milestone for non-π-conjugated DUV NLO materials.
TL;DR: In this article , the authors review the recent progress in metasurface-enabled optical waveplates, which cover both basic principles and emerging applications, and provide an overview of conventional half and quarter waveplates as well as their use in wavefront shaping applications, followed by a discussion of advanced waveplates including multifunctional waveplates and all-polarization generators.
Abstract: Abstract The polarization of light is crucial for numerous optical applications ranging from quantum information processing to biomedical sensing due to the fundamental role of polarization as another intrinsic characteristic of optical waves, which is uncorrelated with the amplitude, phase, and frequency. However, conventional optical waveplates that enable polarization control are based on the accumulated retardation between two orthogonally polarized electric fields when light propagates a distance much larger than its wavelength in birefringent materials, resulting in bulky configurations and limited functionalities. Optical metasurfaces, ultrathin arrays of engineered meta-atoms, have attracted increasing attention owing to their unprecedented capabilities of manipulating light with surface-confined configurations and subwavelength spatial resolutions, thereby opening up new possibilities for revolutionizing bulky optical waveplates with ultrathin planar elements that feature compactness, integration compatibility, broadband operation bandwidths, and multiple functionalities. Herein, we review the recent progress in metasurface-enabled optical waveplates, which covers both basic principles and emerging applications. We provide an overview of metasurface-based conventional half- and quarter-waveplates as well as their use in wavefront shaping applications, followed by a discussion of advanced waveplates, including multifunctional waveplates and all-polarization generators. We also discuss dynamic waveplates based on active metasurfaces. Finally, we conclude by providing our outlook in this emerging and fast-growing research field.