Index Slab Waveguide Research Articles

Optimization of a Waveguide Grating for Normal TM Mode Coupling

The conditions for maximum longitudinal electric field of a TM mode at the surface of a step index slab waveguide, and the value of this maximum are given in a normalized analytical form. They are applied to a grating coupling structure corresponding to a resonant laser mirror or to optical interconnects involving a normally incident free space wave and a singlemode slab waveguide.

Zero dispersion in step index slab waveguides

Specific features of the dispersion in step index slab waveguides, such as zero waveguide dispersion and zero group delay difference between modes, are shown to be described by normalized expressions involving two normalized structure parameters only. The complete subset of dual-mode waveguide structures exhibiting wavelength independent propagation constant difference is identified, and its importance for sensor applications is emphasized.

Optical Fiber Communication Systems

The Communications Toolbox: Introduction. Probability and Random Variables. Some Important Probability Distributions. Signals and Systems. Random Processes. Spectral Analysis. Narrowband Signals and Systems. Elements of Detection Theory. From Light to Signals. Basic Optical Fiber Communications Components: Introduction. The Refractive Index and the Laws of Reflection and Refraction. Total Internal Refraction. Step Index Fibers and Slab Waveguides. Maxwell's Equations in the Slab Waveguide. Even Propagation Modes. Odd Propagation Modes. Number of Modes and Single-Mode Fibers. Phase Velocity. Group Velocity. Attenuation and Dispersion. Dispersion-Shifted and Dispersion-Flattened Fibers. Polarization-Maintaining and Single-Polarization Fibers. The P-N Junction. Single Heterostructure. Double Heterostructure. LED Physical Structure. The LED Rate Equation. LED Output Spectrum. LED Modulation Response. The Fabry-Perot Resonator. Semiconductor Laser Physical Structure. Laser Output Spectrum--Spectral Width and Linewidth. Bragg Reflections. Distributed Feedback (DFB) and Distributed Bragg Reflection (DBR) Lasers. Rate Equations. The Steady-State Solution to the Rate Equations. Laser Modulation--Step Response. Laser Modulation--Sinusoidal Frequency Response. Relative Intensity Noise (RIN), Phase and Frequency Noise, Chirp. Laser Package. The PIN Photodiode. The Avalanche Photodiode, ADP. Basic Binary Optical Communication System: Introduction. System Description. Performance Evaluation. Coherent Systems: Motivations and Basics. Fundamental Receiver Sensitivity--Homodyne Systems. Heterodyne Systems--Synchronous Detection. Heterodyne Systems--Asynchronous Detection. Heterodyne Systems--Weakly Synchronous Detection. Summary and Comparison of Fundamental Sensitivities. Optical Hybrids. Phase Noise and Linewidth. Synchronous Systems. Asynchronous Systems. Weakly Synchronous Systems. How to Deal with Phase Noise--Summary. Polarization Fluctuations. Appendix A--Statistics of Phase Noise to Amplitude Conversion. Appendix B--Evaluation of Averages by Quadrature Rules. Optical Amplifiers: Introduction. Semiconductor Amplifiers. Erbium-Doped Fiber Amplifier. Comparison of Major SOA and EDFA Characteristics. Other Fiber Amplifiers. Soliton Systems: Intuitive Explanation of Solitons. Advantages of Solitons for Long Distance Transmission. Derivation of Solitons. Amplitude, Duration, Energy, and Power. Higher-Order Solitons. Qualitative Physical Explanation of Solitons. Estimation of Peak Pulse Power Required for Solitons. Fiber Loss and its Compensation. Lumped Amplifiers in Soliton Systems. Polarization Dispersion. Amplified Spontaneous Emission Noise in Soliton Systems. Error Rates in Soliton Systems. Soliton Experiments. Using Recirculating Loops. Wavelength Division Multiplexing with Solitons. Bidirectional Soliton Systems. Sources of Soliton Pulses. Beyond the Gordon-Haus Limit. Multichannel Systems: Introduction. Time-Division Multiplexing (TDM). Wavelength-Division Multiplexing. Subcarrier Multiplexing. Code-Division Multiplexing. Space-Division Multiplexing. Network Issues.

A comparison between different propagative schemes for the simulation of tapered step index slab waveguides

The performance and accuracy of a number of propagative algorithms are compared for the simulation of tapered high contrast step index slab waveguides. The considered methods include paraxial as well as nonparaxial formulations of optical field propagation. In particular attention is paid to the validity of the paraxial approximation. To test the internal consistency of the various methods the property of reciprocity is verified and it is shown that for the paraxial algorithms the reciprocity can only be fulfilled if the paraxial approximation of the power flux expression using the Poynting vector is considered. Finally, modeling results are compared with measured fiber coupling losses for an experimentally realized taper structure.

Sensitivity optimization of a grating coupled evanescent wave immunosensor

The sensitivity of a grating coupled evanescent wave step index slab waveguide sensor for ultra-thin films is given by a single normalized expression.

Finite‐difference beam propagation method using the oblique coordinate system

AbstractUntil now, the rectangular coordinate system has been used mainly for the analysis of optical beam propagation. Hence, when a tilted waveguide is analyzed, the core shape is expressed by a stepped approximation which causes the quantization error so that the error accumulates as the field propagates.In this paper, with a view to overcome this problem, the finite‐difference beam‐propagation method is proposed in which the oblique coordinate system is employed. To confirm the effectiveness of the method, the propagation error of the fundamental mode is evaluated by the model mismatch loss in a tilted step index slab waveguide. It is found that the mode mismatch loss is kept low as the quantization error in the rectangular coordinate system is now eliminated. Further, as an example of application of this method, an optical waveguide bend is analyzed and the effects of coherent coupling are investigated. It is pointed out that the computational region can be made narrower in this method compared with that required in the rectangular coordinate system.

Field Intensity and Power Confinement of Four-layer Slab Waveguides with Various Refractive Index Profiles in the Guiding Region

Relative field intensity distributions in three different types of structures, i.e. Step index Slab Waveguide (SSW), Semi-parabolic index Slab Waveguide (SPSW) and Parabolic index Slab Waveguide (PSW) have been analytically derived and computed. It is found that the field in the guiding region is maximum in case of the PSW structure. Analytical expressions for the relative power confinement factors have also been obtained. The applicability of these results in the estimation of coupling coefficient of some of the Distributed Feed Back (DFB) lasers have also been briefly shown

Computer—aided estimation of refractive—index profile of optical waveguides from propagation—mode near field pattern

AbstractSeveral methods have been proposed for estimating the structural parameters of a waveguide from transmission characteristics of the guided mode. In this paper, a simple and effective method is proposed for estimating the index profile in the cross section of the optical waveguide. In this method the measured field distribution of the guided mode and that calculated from the assumed index profile are compared directly and the index profile is sought for which the two field distributions coincide. To confirm the validity of the method, numerical simulations have been carried out for several graded index slab waveguides. Even if the simplest step index profile is assumed as the initial guess of the profile, the index profile of the waveguide can be estimated with practically sufficient accuracy. In this method, no differential process is needed for the measured values nor a high‐degree smoothing operation. Hence, the method is expected to be superior to others in terms of noise tolerance.

Slab waveguides characterized by moments of the index profile

The fundamental mode of a symmetric slab waveguide is described to a high degree of accuracy using only two moments of the refractive index profile rather than its exact form. The two moments can be used to define an equivalent step index slab waveguide, and the fundamental mode propagation constant of an arbitrary profile guide is given by the step index value multiplied by a simple correction factor. The limit to single-mode operation, the second-mode cutoff point, is also given by a simple formula requiring only profile moments. Numerical confirmation of the method is given.

Exact solutions for TM modes in graded index slab waveguides

Three continuous profiles for the dielectric constant are derived, which allow exact solutions of the vector wave equation, including all terms in the gradient of the profile, for both TE and TM modes on slab waveguides. The dielectric constant has been assumed to be a scalar quantity; i.e., the medium is isotropic.