Haibo Liang

An Optical Mode-Matching Method With Improved Accuracy and Efficiency

Two fundamental principles of the mode-matching method-mode orthogonality and tangential field continuity conditions have been revisited in depth. With a finite number of modes employed in the conventional method, the tangential field continuity condition at the waveguide-discontinuity interface fails leading to a field mismatch error. We propose an alternate, superior mode-matching method implemented by reconstruction of the auxiliary coefficient matrix, rather than by applying the above-mentioned continuity and orthogonality. Detailed transfer-matrix equations have been derived for the finite-mode-number case. We showed that the improved mode-matching method yields a smaller field mismatch error under equal computational effort. Examples of bent and faceted waveguide structure have been investigated and the numerical simulation results demonstrated that the newly proposed method has the merits of simple implementation, high accuracy, and high computational efficiency for application in high-index-contrast photonic integrated circuits.

Insights into complex Berenger modes: a view from the weighted optical path distance perspective

We present a simple and efficient approach for higher-order Berenger mode computation. We establish the physical mapping between radiation modes and complex Berenger modes, and theoretically prove that the higher-order substrate Berenger modes and cladding Berenger modes can converge to a cluster of complex modes with the same phase angle. This model can be explained by weighted optical path distance in both cladding and substrate, and can be implemented by adjusting parameters of perfectly matched layers. A germanium (Ge) photodetector is utilized to evaluate the merits of this method in terms of robustness, efficiency, and accuracy.

Vector Mode Analysis of Optical Waveguides by Quadratic Spline Collocation Method

We present an accurate, e-cient numerical analysis for vector modes of dielectric optical waveguide structures with an arbitrary refractive index proflle using a quadratic spline collocation method (QSCM). The unknown weights of the polynomials are determined by forcing the errors at the collocation points to be zero. Consequently, the original second order difierential equation is converted to a set of algebraic equations which can be solved by matrix techniques. The proposed QSCM method demonstrates better performance than the standard flnite-difierence method of the same convergence rate in terms of grid size with the same degree of computational complexity.

Improved Complex Mode Matching Method for Optical Waveguides Analysis

We present an improved eigen-mode matching method without using mode orthogonality and normalization. Coupling between SOI waveguides and an anti-guided structure are utilized to show the efficiency and accuracy of the proposed method.

A novel silicon nitride slot waveguide

We propose and study a box-shaped waveguide based on Si3N4 which confines the light in a sub-wavelength region. The mode characteristics of the proposed structure have been investigated thoroughly.

Roles of high order bending modes in optical wave coupling

Radiation coupling plays a key role in the bending waveguide structure with very small bending radius. Insights of radiation coupling and energy transfer by way of high order bending modes have been discussed. Modes in bending waveguide structures with small bending radii are investigated.

An Investigation into the Phase Angles of High-Order Berenger Modes

We theoretically investigate the phase angles of high order Berenger modes and propose a weighted optical path distance method to converge the phase angles.

Circuit Model Analysis of Radiation Coupling

We apply a circuit model to investigate radiation coupling in tapered resonant cavity chains. This circuit model shows computation efficiency and accuracy through the comparison with FDTD.