Kajal Mondal

Characteristics of transverse-stress-induced phase change through a distinct dual-mode fiber in a Sagnac loop

We report here the experimental realization of a fiber-optic transverse-stress sensor devised by a dual-mode optical-fiber segment in a standard Sagnac interferometer loop. The intermodal interference of the LP01 and LP02 modes of the dual-mode fiber (DMF) configuration is analyzed theoretically in the platform of polarization transmittance of the Sagnac loop in implementing the theoretical model. Several experimental measurements for various conditions of applied birefringence are studied at length and the results are compared with those estimated theoretically toward configuring a stress-measuring device. The study provides an understanding of the underlying physics of the working of DMF interference in a Sagnac configuration.

Designing Ultra-High-Birefringent Photonic Crystal Fibers with Circular Air Holes in the Cladding

Abstract This article reports a new air-silica photonic crystal fiber structure of high birefringence (~10−2). The birefringence is due to large axial anisotropy introduced in the fiber geometry by a preferred arrangement of circular air holes of different sizes in the cladding structure along orthogonal directions. A series study of birefringence and cut-off properties of the fiber that leads to optimization of geometrical parameters toward maximized birefringence achievable in the single-mode regime through this micro-structure is provided. Also, other inherently related modal properties of the fiber and the stack design toward preform realization are investigated. The findings should be useful in realizing high-performance high-birefringence fiber.

Investigation of structural dependence of host erbium-doped triangular-lattice PCF on lasing properties and design of high performance laser

A detailed study is presented on the lasing properties of an erbium-doped photonic crystal fiber (PCF) laser. The effects of the host PCF’s structure and laser parameters on continuous-wave laser emission are analyzed by considering the confinement and overlap of pump and signal fields in the gain medium for varying values of pitch, hole diameter, and doping radius. For analysis, we used a finite-difference mode-calculation algorithm devised with standard population and propagation rate-equation solver. Our analysis, applied to an experimentally realized PCF laser, reproduces the observed/reported data, thereby showing the efficacy of our analysis. Finally, a fiber geometry to realize a laser with threshold as low as 6 mW using a short fiber length of 0.52 m is prescribed. The aim of the design is to greatly reduce splice loss with standard single-mode SM28/G.652 fiber while maintaining the optimum performance. These results are new in PCF laser research and should be useful in realizing high performance PCF-based laser devices.

Binary Multi-clad Microstructured Fiber with All-normal Dispersion for Two-octave Spanning flat-top Coherent Supercontinuum Generation

We demonstrate the possibility of realizing two-octave spanning (990-2546 nm) flat-top coherent Supercontinuum Generation in a host lead-silicate binary multi-clad microstructured fiber by appropriate combination of designed fiber geometry and input pulse-parameter(s).

Switchable Hermite Gaussian Beam Generation in Dual-mode Fiber by Controlling Incident Polarization

We analyze theoretically and experimentally demonstrate the selective excitation in dual-mode-fiber with Gaussian beam generating switchable/asymmetric hybrid polarized Hermite-Gaussian beam with strong dependence of the output beam characteristics on the input beam polarization and fiber-length.

Performances of ring-shaped cladding structured PCF laser and triangular-lattice PCF laser

We perform a detailed study on erbium-doped ring-shaped cladding structured photonic crystal fiber (PCF) laser towards achieving high performance fiber laser. We achieve a better lasing performance as compared to triangular-lattice PCF.

Exact mode field solutions and dispersion characteristics of N-layered high-index-core Bragg fiber

We report here the outcomes of our detailed studies on the propagation and dispersion characteristics of N-layered high-index-core Bragg fiber by the analytical evaluations of the mode effective indices and hence the mode-field distribution.

Er +3 -doped fiber amplifier in triangular PCF host revisited: higher gain, low splice loss

With a view to enhancing the performance of all-fiber amplifier using Er+3-doped triangular-lattice photonic crystal fiber (PCF), we performed a detailed study of the amplifying characteristics of the PCF host by varying all associated parameters towards achieving high gain and lower optimum doped fiber length (minimum length required to get the maximum level of gain). A finite difference (FD) mode- convergence analysis is used to determine the modal propagation characteristics in the structure, which is then used to solve a standard propagation and population rate equation. Our results show that a spectral gain of the amplifier as high as 51 dB and that too over a short length ~2.4 m of the active fiber is achievable by optimizing the gain dependent parameters and the transverse geometry of the fiber. Aimed at field-deployment of the amplifier as inline component, we optimize splicing/coupling loss (considering the mismatch of fundamental modes only) of this all-fiber device. Notably, the splice loss with standard telecom-grade SMF-28 fiber is minimized through an improved mode-matching of the design. These results are new in fiber amplifier research and would make useful contribution to realize high-performance PCF-based amplifiers and devices.