Spectral index method for rib waveguide analysis

Application of the spectral index method to laser diode design

“…where for symmetric modes The boundary condition that minimizes the gradient discontinuity across the base of the rib is derived by P. C. Kendall et al [7] and is repeated here:…”

“…Use of the Fourier identity and insertion of (6) and (15) gives Equation (26), derived by Kendall et al [7], is the eigenvalue equation fot' the SIM that gives the modes for the rib waveguide and must be solved numerically.…”

Analysis of coupled rib and buried waveguides for efficient mode-spot converters

“…The concept of effective width [5] which is one of the main assumptions of the SI method is used to model the penetration of the optical field into the air region. Thus, the original air-semiconductor boundaries are displaced to new ones on which the field is set to zero.…”

“…Although there are several versatile numerical methods, such as Finite Differences (FD) and Finite Elements (FE), which are slraightforward to apply and can provide high accuracy, their relatively long run-times make them quite inefficient, either within an iterative design process or when the structure to be analysed has large dimensions as in the present case. In these situations accurate semi-analytical approaches such as the Spectral Index (SI) [5,6,7] or Free Space Radiation Mode methods [8,9,10] are often more suitable for design, rapidly yielding excellent results. The novel spectral method developed here for the analysis of the mode spot tapers described above, successfully combines the Spectral Index (SI) method [5], previously restricted to the analysis of single and coupled rib waveguides, and the Free Space Radiation Mode method (FSRM) [8], previously used for the analysis of low contrast buried waveguides.…”

“…In these situations accurate semi-analytical approaches such as the Spectral Index (SI) [5,6,7] or Free Space Radiation Mode methods [8,9,10] are often more suitable for design, rapidly yielding excellent results. The novel spectral method developed here for the analysis of the mode spot tapers described above, successfully combines the Spectral Index (SI) method [5], previously restricted to the analysis of single and coupled rib waveguides, and the Free Space Radiation Mode method (FSRM) [8], previously used for the analysis of low contrast buried waveguides. The new method presented is simple and fast, giving the propagation constants and field profiles of the coupled waveguides in a matter of seconds.…”