Review of the technology of a single mode fiber coupling to a laser diode

Mismatch considerations in laser diode to single-mode circular core triangular index fiber excitation via upside down tapered hemispherical microlens on the fiber tip

Allowable aperture considerations for laser diode coupling to cylindrical lensed fiber: Efficiency computation with ABCD matrix

Abstract We employ ABCD matrix formalism in order to investigate the coupling optics involving laser diode to single-mode circular core parabolic index fiber excitation via upside-down tapered hyperbolic microlens on the fiber tip. Analytic expressions for coupling efficiencies both in absence and in presence of transverse and angular mismatches are formulated. The concerned investigations are made for two practical wavelengths namely 1.3 µm and 1.5 µm. The execution of the prescribed formulations involves little computation. It has been found that the wavelength 1.5 µm is more efficient in respect of coupling. It is also seen that the present coupling device at both the wavelengths shows more tolerance with respect to angular mismatch. As regards tolerance with respect to transverse mismatch, the result is poor at both the wavelengths used. Consequently, it is desirable that designers should not to exceed transverse mismatch beyond 1 μm.

Laser Diode to Single-Mode Circular Core Parabolic Index Fiber Coupling via Upside-Down Tapered Hyperbolic Microlens on the Tip of the Fiber: Prediction of Coupling Optics by ABCD Matrix Formalism

Study of coupling optics involving graded index fiber excitation via upside down tapered parabolic microlens on the fiber tip

Laser diode to single-mode circular core dispersion-shifted/dispersion-flattened fiber excitation via hyperbolic microlens on the fiber tip: Prediction of coupling efficiency by ABCD matrix formalism

Abstract The ABCD matrix prescribed for a upside down tapered hemispherical microlens end drawn from a parabolic index circular core fiber is used to formulate analytical expression of coupling efficiency of excitation of this optical device by a laser diode. In our analysis, we assume Gaussian field distribution for both the source and the fiber. For maximum coupling efficiency, the lens transmitted spot size of the source should match with the fiber spot size. In our investigations, we employ two different laser diodes emitting wavelengths 1.3 μm and 1.5 μm respectively. It is found that the wavelength 1.5 μm is more efficient in the context of present coupling optics. Our formalism predicts the concerned coupling optics excellently and the execution of our formalism requires little computations. This simple but accurate technique is expected to benefit the system designers and packagers concerned with optimum launch optics.

Excitation of Single-mode Circular Core Parabolic Index Fiber by Laser Diode via Upside Down Tapered Hemispherical Microlens on the Tip of the Fiber: Estimation of Coupling Efficiency by Application of ABCD Matrix Formalism

Abstract We report the theoretical investigation of the coupling optics involving laser diode to single-mode circular core parabolic index fiber via upside down tapered hemispherical microlens on the tip of the fiber in the presence of possible transverse and angular mismatches. Using the relevant ABCD matrix for such tapered hemispherical microlens, we formulate analytical expressions for the coupling efficiencies in the presence of the said two mismatches. Further, the transmitted spot size of the source via the hemispherical lens and the tapered region should match with the spot size of the fiber for obtaining maximum coupling. The investigations have been made for two practical wavelengths, namely 1.3 and 1.5 μm in order to find the tolerance of this coupling device with respect to the said kinds of mismatches at the concerned wavelengths. Although our simple method predicts the concerned coupling optics excellently, the evaluation of the concerned efficiencies and associated losses involve little computations. Thus this user-friendly technique and also the results found thereof will benefit the designers and packagers who are working in the field of optical technology.

Mismatch Considerations in Excitation of Single-Mode Circular Core Parabolic Index Fiber by Laser Diode via Upside Down Tapered Hemispherical Microlens on the Tip of the Fiber

Abstract Based on the simple series expression of fundamental mode in dispersion-shifted and dispersion-flattened fibers, we formulate analytical expressions for far-field pattern of such fibers and evaluate them. The concerned calculations require much less computations. Taking three typical trapezoidal fibers as example of dispersion-shifted fiber, we show that our results match excellently with the exact numerical results. As example of dispersion-flattened fiber, we choose two parabolic profile W and two step profile W fibers for our study and here also, our estimations agree excellently with the exact numerical results. The present formalism can also be used for predicting different propagation characteristics associated with the far-field. Further, one can also predict the fundamental modal field from the knowledge of far-field pattern. This simple but accurate formalism developed will benefit the system engineers working in the field of optical technology.

Simple Method for Prediction of Far-Field Patterns of Single-mode Dispersion-shifted and Dispersion-flattened Fibers

An optically pumped doped fiber amplifier has emerged as an important device in all optical technology. It provides broad band amplification in case of multi-channel optical signals. Fibers belonging to low V number are important from the point of view of evanescent field coupling. Accordingly, for study of such fibers in all optical technology, one needs to investigate the response of doped fiber amplifier in the low V region. Therefore, knowledge of fundamental modal field in doped single-mode fiber of low V number is essential to extend the study in the field of variation of modal intensity with radial distance from the axis of the fiber. This study is extremely important in the context of processing information. Using the simple but accurate power series expression for fundamental mode of graded index fiber in the low V region, we predict how the modal intensity varies with radial distance in case of both signal and pump. Choosing some typical step and parabolic index fibers of low V number, we show that our estimations agree with the exact results. Our formalism involves prescription of analytical formulation of the concerned parameters and the execution involves little computation. Thus the present method will be extremely user friendly with the system users.

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A Simple Method for Study of Radial Variation of Pump and Signal Intensities in Mono-Mode Erbium-Doped Graded Index Fiber Amplifier in the Low V Region

Bishuddhananda Das

Papers

Laser diode to single-mode circular core dispersion-shifted/dispersion-flattened fiber excitation via hyperbolic microlens on the fiber tip: Prediction of coupling efficiency by ABCD matrix formalism

Excitation of Single-mode Circular Core Parabolic Index Fiber by Laser Diode via Upside Down Tapered Hemispherical Microlens on the Tip of the Fiber: Estimation of Coupling Efficiency by Application of ABCD Matrix Formalism

Mismatch Considerations in Excitation of Single-Mode Circular Core Parabolic Index Fiber by Laser Diode via Upside Down Tapered Hemispherical Microlens on the Tip of the Fiber

Simple Method for Prediction of Far-Field Patterns of Single-mode Dispersion-shifted and Dispersion-flattened Fibers

A Simple Method for Study of Radial Variation of Pump and Signal Intensities in Mono-Mode Erbium-Doped Graded Index Fiber Amplifier in the Low V Region