Birefringent Fiber Research Articles

Suppression of polarization instability in ultrashort Fabry–Pérot fiber laser

Due to the weak birefringence from the intracavity fiber, vector solitons are easily generated in GHz-fundamental-repetition-rate mode-locked fiber lasers, which can exhibit diverse time-varying polarization dynamics. These soliton dynamics can lead to polarization instability of the pulse train, which prevents industrial and scientific applications that require stable and uniform pulse trains. However, it is hard to suppress the polarization instability due to insufficient space for inserting traditional polarizers and difficulties in enhancing the fiber birefringence in the ultrashort fiber laser cavity. To this end, here we propose an alternative method that can effectively transform the vector solitons into scalar solitons by exploring gold nanorod (GNR) film as a polarizer in the laser cavity. First, the theoretical studies of polarization dynamics in ultrashort Fabry–Pérot (FP) fiber lasers with and without intracavity GNR film are conducted. The results indicate that the use of GNR film can significantly suppress the polarization instability and generate scalar solitons. Then, the large-scale preparation of GNRs with longitudinal surface plasmon resonance absorption peak of >1380 nm is realized by a two-step seed-mediated method, and the GNR film with an operation wavelength range covering the C + L band is fabricated by electrospinning. Finally, we apply the GNR film to a 2-cm-long FP fiber laser, and convert polarization rotation vector solitons to linearly polarized solitons (LPSs) at 1.5 μm. The polarization extinction ratio of the improved LPS pulse train is up to 33 dB.

A highly birefringent photonic crystal fiber based on a central trielliptic structure: FEM analysis

In this study, a highly birefringent photonic crystal fiber (PCF) with a simple center trielliptic is presented. The finite element method is applied in this study to analyze PCF. By adjusting the ellipticity and other parameters, the fiber performances can be optimized. As the parameters of the PCF are finalized, i.e., the number of cladding N = 4, lattice constant Λ = 1.6 μm, and ellipticity η = 2, a high birefringence of 3.56 × 10−2 can be obtained at the wavelength λ = 1.55 μm . Moreover, the dispersions of the X- and Y-polarized modes are relatively flat in the range of 1 μm to 1.55 μm along with a confinement loss as low as 9.63 × 10−6 dB m−1. Besides, this structure has demonstrated remarkable robustness, maintaining its superior performance even when subjected to significant displacements or rotations. Due to the characteristics of the high birefringence and low confinement loss, this PCF can be used for long distance optical fiber communication, fiber sensing, dispersion compensation, and supercontinuum generation.

Highly Birefringent Anti-Resonant Hollow-Core Fiber With a Low Loss

Highly Birefringent Anti-Resonant Hollow-Core Fiber With a Low Loss

Highly dispersive optical solitons in birefringent fibers with Lakshmanan–Porsezian–Daniel model having multiplicative white noise

Highly dispersive optical solitons in birefringent fibers with Lakshmanan–Porsezian–Daniel model having multiplicative white noise

Dual‐Mode Polarization Control with Quasi‐Bound States in the Continuum

AbstractFull control of light polarization is one of the most sought‐after functionalities in nanophotonics since it allows the replacement of bulky optical components like wave retarders. Here, the study reports the theoretical and experimental demonstration of an ultra‐compact dual‐mode frequency selective polarization controller that leverages the topological features of symmetry protected quasi‐bound states in the continuum (q‐BICs) supported by a silicon‐based nanostructure. Thanks to q‐BIC resonances, arbitrarily polarized incoming light can be converted into linearly polarized light without resorting to the local phase tuning mechanisms that characterize optical metasurfaces. Moreover, the dual‐mode operating regime allows to select the transmitted polarization without modifying the device orientation, therefore overtaking the concept of the wire grid polarizer. The experimental findings show that the proposed meta‐polarizer possesses an extinction ratio of ≈40 dB for two linear cross‐polarization excitations. These results pave the way for a novel class of ultra‐compact devices that can be used to compensate unwanted birefringence in optical fibers or to control polarization in complex media environments.

Single-short-cavity dual-comb fiber laser with over 120 kHz repetition rate difference based on polarization multiplexing.

An all-fiber single-short-cavity dual-comb laser with a high repetition rate of up to 500 MHz and a high repetition rate difference of over 120 kHz was demonstrated. The laser setup exploits high birefringence of a polarization-maintaining gain fiber to generate asynchronous combs based on the polarization-multiplexing method. By adopting short-linear-cavity and all-birefringent configuration, a repetition rate difference several orders of magnitude larger than that of a previous work was achieved. The soliton dual-comb showed good mutual coherence and stability, which reveals the potential to enhance the acquisition rate and accuracy of dual-comb measurement systems.

Optical soliton solutions of the coupled Radhakrishnan-Kundu-Lakshmanan equation by using the extended direct algebraic approach

The analytical soliton solutions place a lot of value on birefringent fibres. The major goal of this study is to generate novel forms of soliton solutions for the Radhakrishnan-Kundu-Lakshmanan equation, which depicts unstable optical solitons that arise from optical propagations using birefringent fibres. The (presumably new) extended direct algebraic (EDA) technique is used here to extract a large number of solutions for RKLE. It gives soliton solutions up to thirty-seven, which essentially correspond to all soliton families. This method's ability to determine many sorts of solutions through a single process is one of its key advantages. Additionally, it is simple to infer that the technique employed in this study is really straightforward yet one of the quite effective approaches to solving nonlinear partial differential equations so, this novel extended direct algebraic (EDA) technique may be regarded as a comprehensive procedure. The resulting solutions are found to be hyperbolic, periodic, trigonometric, bright and dark, combined bright-dark, and W-shaped soliton, and these solutions are visually represented by means of 2D, 3D, and density plots. The present study can be extended to investigate several other nonlinear systems to understand the physical insights of the optical propagations through birefringent fibre.

Influence of hematoxylin and eosin staining on linear birefringence measurement of fibrous tissue structures in polarization microscopy.

For microscopic polarization imaging of tissue slices, two types of samples are often prepared: one unstained tissue section for polarization imaging to avoid possible influence from staining dyes quantitatively and one hematoxylin-eosin (H&E) stained adjacent tissue section for histological diagnosis and structural feature identification. However, this sample preparation strategy requires high-quality adjacent tissue sections, and labeling the structural features on unstained tissue sections is impossible. With the fast development of data driven-based polarimetric analysis, which requires a large amount of pixel labeled images, a possible method is to directly use H&E stained slices, which are standard samples archived in clinical hospitals for polarization measurement. We aim to study the influence of hematoxylin and eosin staining on the linear birefringence measurement of fibrous tissue structures. We examine the linear birefringence properties of four pieces of adjacent bone tissue slices with abundant collagen fibers that are unstained, H&E stained, hematoxylin (H) stained, and eosin (E) stained. After obtaining the spatial maps of linear retardance values for the four tissue samples, we carry out a comparative study using a frequency distribution histogram and similarity analysis based on the Bhattacharyya coefficient to investigate how H&E staining affects the linear birefringence measurement of bone tissues. Linear retardance increased after H&E, H, or E staining (41.7%, 40.8%, and 72.5% increase, respectively). However, there is no significant change in the imaging contrast of linear retardance in bone tissues. The linear retardance values induced by birefringent collagen fibers can be enhanced after H&E, H, or E staining. However, the structural imaging contrasts based on linear retardance did not change significantly or the staining did not generate linear birefringence on the sample area without collagen. Therefore, it can be acceptable to prepare H&E stained slices for clinical applications of polarimetry based on such a mapping relationship.

Distributed and polarimetric pressure sensitivity in spun highly birefringent optical fibers.

We examine experimentally the influence of the fiber inelastic twist on polarimetric sensitivity to hydrostatic pressure and pressure sensitivity in a Rayleigh-scattering-based optical frequency-domain reflectometer (OFDR) for highly birefringent side-hole fibers. The fibers were drawn from the same preform with different spin pitches varying from 5 mm to 200 mm. We also demonstrate that the sensitivities of spun fiber can be estimated analytically based on its spin pitch, measured birefringence, and the sensitivity of the corresponding non-twisted fiber, showing good agreement with the experimental results. We proved that polarimetric sensitivity to pressure decreases with the shorter spin pitches, while distributed pressure sensitivity decreases for the one polarization eigenmode and increases for the second polarization eigenmode. Therefore, the spun-fibers can operate well as the polarimetric sensors of other physical parameters inducing circular birefringence even under varying pressure. Moreover, they can be used to obtain the desired difference between sensitivities for both polarization eigenmodes.

Dispersive optical soliton solutions in birefringent fibers with stochastic Kaup–Newell equation having multiplicative white noise

In this article, we study for the first time the stochastic Kaup–Newell equation in birefringent fibers. Three integration algorithms are applied, namely, the unified Riccati equation expansion method, the addendum to Kudryashov's method, and the addendum to modified sub‐ODE method. Many types of optical soliton solutions such as Jacobi‐elliptic function solutions, Weierstrass elliptic function solutions, bright solitons, dark solitons, singular solitons, and periodic function solutions are obtained. Numerical schemes give a visual perspective to the solutions derived analytically.

Vector pure-quartic soliton molecule fiber laser

Pure-quartic solitons (PQSs) balanced by the fourth-order dispersion (FOD) and nonlinearity in weakly birefringent optical fibers exhibit unique characteristics that differ from those of traditional solitons. Owing to the long oscillating tail of the PQS, soliton trapping can be easily promoted either between the sub pulses inside the molecule or along the two polarization axes of the birefringent fiber. Thus, observing the interaction and motion dynamics of vector PQS molecules promotes great opportunities for unveiling new mechanisms of soliton molecular complexity. In this work, we numerically explore the transient dynamics of vector PQS molecules by solving the coupled Ginzburg-Landau equations which are contributed by the FOD. Diverse real-time dynamics of vector PQS molecules are demonstrated for the first time, including stationary and pulsating, which originate from the multi-scale energy exchange inside the molecule and between the orthogonal axes depending on the nonlinear effect. In addition, we reveal that the buildup process of vector PQS molecules includes splitting, pulsating, and synchronization. The related dynamics of the pulse separation and phase difference that constitute the relevant internal degrees of freedom of the molecule are also mapped. These efforts may shed new insights into understanding the internal dynamics of soliton molecular complexes and decomposing the dynamics of complex nonlinear systems.

Waist diameter dependent temperature and strain sensitivities of tapered high birefringence fiber in Sagnac interferometer

The relation of the temperature and strain sensitivities to the waist diameter of the tapered high birefringence fiber (THBF) in Sagnac interferometer is theoretically analyzed and experimentally demonstrated. With a large waist diameter, the occurred Sagnac interference shows sensitive to both temperature and strain. The temperature and strain sensitivities decline as the waist diameter decreases. By contrast, when the waist diameter of the THBF is sufficiently small, both Sagnac and modal interferences are simultaneously generated. The former is only sensitive to temperature, whereas the latter is sensitive to both temperature and strain. As the waist diameter of the THBF decreases, the temperature sensitivities of both the Sagnac and modal interferences diminish, but the strain sensitivity of the modal interference improves. Therefore, the proposed THBF Sagnac interferometer enables simultaneous measurement of temperature and strain variations. Importantly, the strain-insensitive characteristic of Sagnac interference facilitates the discrimination between temperature and strain variations.

New wave behaviors of the Fokas-Lenells model using three integration techniques.

In this investigation, we apply the improved Kudryashov, the novel Kudryashov, and the unified methods to demonstrate new wave behaviors of the Fokas-Lenells nonlinear waveform arising in birefringent fibers. Through the application of these techniques, we obtain numerous previously unreported novel dynamic optical soliton solutions in mixed hyperbolic, trigonometric, and rational forms of the governing model. These solutions encompass periodic waves with W-shaped profiles, gradually increasing amplitudes, rapidly increasing amplitudes, double-periodic waves, and breather waves with symmetrical or asymmetrical amplitudes. Singular solitons with single and multiple breather waves are also derived. Based on these findings, we can say that our implemented methods are more reliable and useful when retrieving optical soliton results for complicated nonlinear systems. Various potential features of the derived solutions are presented graphically.

Stress birefringence in the three-core optical fiber and its effects on the transmission property

This paper investigates the stress field distribution characteristics in the three-core optical fiber. Utilizing Fourier transform analysis of the stress tensor components, it is shown that the constant part in the stress tensor, or the overall elevated value of the oscillation curve, is directly related to the stress induced birefringence. So, an effective method to extract information about stress induced birefringence is acquired. The polarization mode dispersion (PMD) and the relationship between stress induced birefringence and the structural parameter of the optical fiber are investigated by numerical simulation. It is found that the PMD usually decreases with the increase of the distance from the core to the fiber center. And it even reaches zero at a certain distance; while increases again thereafter. Some three-core optical fibers with ultra-low PMD and high transmission rates are designed based on these results.

Qualitative analysis and optical solitons of the coupled Biswas–Arshed equation in single mode polarization-preserving birefringence fibers

In this article, the topological phase portrait and dynamical behavior of the coupled Biswas–Arshed equation in single mode polarization-preserving birefringence fibers are discussed via qualitative analysis of planar dynamic system. When assigning values to the parameters of the system with perturbation terms, the system exhibits chaotic behavior. By the polynomial complete discrimination method, the optical solitons are obtained such as dark solitons, bright solitons, dark-bright solitons, and bright-dark solitons. Moreover, the physical properties of optical solitons are studied through two-dimensional and three-dimensional diagrams, density maps and contour maps of optical solitons. Finally, the modulation instability of the system is analyzed via standard linear stability.

A study of polarization compensation for quantum networks

The information-theoretic unconditional security offered by quantum key distribution has spurred the development of larger quantum communication networks. However, as these networks grow so does the strong need to reduce complexity and overheads. Polarization-based entanglement distribution networks are a promising approach due to their scalability and no need for trusted nodes. Nevertheless, they are only viable if the birefringence of all-optical distribution fibres in the network is compensated to preserve the polarization-based quantum state. The brute force approach would require a few hundred fibre polarization controllers for even a moderately sized network. Instead, we propose and investigate four different realizations of polarization compensation schemes that can be used in quantum networks. We compare them based on the type of reference signals, complexity, effort, level of disruption to network operations and performance on a four-user quantum network.

Highly sensitive torsion sensor based on a coupled optoelectronic oscillator incorporating nonlinear polarization rotation.

We propose and demonstrate a new, to the best of our knowledge, technique to implement a high-speed and highly sensitive torsion sensor based on a coupled optoelectronic oscillator (COEO) incorporating nonlinear polarization rotation (NPR). The COEO consists of a mode-locked laser loop and an OEO loop. In the laser loop, the NPR effect effectively induces intensity- and wavelength-dependent loss, which acts as a Lyot birefringent fiber filter. When twisting the polarization-maintaining fiber (PMF), the transmission of the filter varies as well as the laser output wavelength. In the OEO loop, the optical source is provided by the output signal of the mode-locked laser. The variation in the optical carrier wavelength changes the time delay and the oscillation frequency of the OEO loop. The oscillation frequency shift is a linear function of the twist angle. Sensitivities of -60.006 Hz/deg over 360° for a 48 cm PMF and -180.996 Hz/deg over 92° for a 22 cm PMF are achieved.

Stability of kink, anti kink and dark soliton solution of nonlocal Kundu–Eckhaus equation

We study the modulational instability and soliton solution for nonlocal Kundu–Eckhaus (KE) equation which is distinctly different from KE equation. KE equation can describe the dynamical behavior of optical pulse envelopes in birefringent fiber. Although, the present equation has novel space, which induce new physical effects and inspire novel physical applications. Therefore, through the Jacobi elliptic function method, the elliptic function solution is derived for the nonlocal KE. Deng et al. (2022) found the N-soliton solution for nonlocal KE equation by the use of Hirota bilinear method. Though, the present problem of the solution is new which is Jacobi elliptic function solution. It is found that the solution exhibits a variety of forms of soliton as dark, kink and antikink soliton due to distinct choices of values of focusing and defocusing parameters. Importantly, with the use of the Jacobi elliptic solution, the role of focusing and defocusing parameters of cubic, quintic nonlinearity and self frequency shift on optical soliton in birefringent fiber for nonlocal KE equation is discussed. The linear stability analysis is used to construct the gain of nonlocal Kundu–Eckhaus equation and using it to analysis the stability/instability of various forms of soliton.

A highly birefringent and compact nonlinear photonic crystal fiber for next-generation optical fiber applications: design and investigation

A highly birefringent and compact nonlinear photonic crystal fiber for next-generation optical fiber applications: design and investigation

Dynamical analysis and new solitary wave patterns of coupled nonlinear Schrödinger model arising in birefringent fibers

Coupled nonlinear Schrödinger type equation is used to represent the transmission of optical signals in birefringent fibers. These types of equations are significant models for a vast range of disciplines, including fluids, nonlinear optics, the theory of deep ocean waves etc. In this manuscript, coupled nonlinear Schrödinger type equation is investigated by using two techniques namely, the G′/(bG′+G+a)-expansion method and the modified Jacobi elliptic expansion schemes. Furthermore, modulation instability analysis is performed on our model. The extracted solutions show dark, Kink and singular solitons behaviors, which are depicted graphically by using surface and line plots. The obtained solutions are unique and novel. The employed integration techniques are widely used to examine exact solutions of various partial differential equations.