The bidirectional eigenmode propagation (BEP) combines the advantages of the transfer-matrix method for propagation and the mode-matching method (satisfying Maxwell's boundary conditions) at longitudinal large discontinuities for forward and backward travelling eigenvalues including discretized radiation modes. The calculated examples include a grating-assisted codirectional coupler for which 20% radiation losses have been found, and a cleaved waveguide facet with 39% reflected intensity and recapture of radiation modes due to a taperlike structure. The BEP is applicable to various types of optical passive (directional coupler, butt-coupling, taper) and active (DBR-, DFB-, and VCSE-laser, detector) devices with large refractive index differences
Abstruct-Heating effects on the light power vs. current characteristic of planar top-emitting vertical-cavity laser diodes are analyzed by thermal, optical and electrical modeling. The twodimensional finite element thermal-electrical simulation considers the spatial current funneling in the top p-doped distributed Bra@ reflector and a current density dependent resistivity of the hetero-barrier. Layered regions are described by anisotropic material parameters. Non-uniform refractive index temperature coefficients of the semiconductor materials are applied in the vertical optical modeling. The strongly inhomogeneous temperature distribution causes thermal increases of emission wavelength and reflectivity as well as decreases of threshold gain and external quantum efficiency with rising current. Finally, the calculated maximum light power is found to be decisively affected by the temperature coefficients of the refractive indices.
The coupling efficiency of square meander-type or grating-assisted codirectional couplers has been calculated so far by common coupled mode theory. The theory presented calculates coupling efficiency, period length, dispersion behavior, etc. on the basis of the propagation of both eigenmodes of the asymmetrical coupler, using mode matching at the boundaries, which can be described as a rotation between the two eigenmodes of the undisturbed waveguide. This method is very fast, simple, accurate and gives a good insight into the physical behavior. Some examples verified by BPM calculations show the significance of this new theory
For the first time we present the integration of a tunable buried four-section DBR-laser butt coupled to a directional coupler based on semi-insulating strip loaded (InGaAsP/InP):Fe waveguides by using selective area epitaxy with large mask areas. Good planarity after the epitaxial regrowth of the waveguide layers has been achieved applying a special preparation of the laser mesa. Average coupling efficiencies of 52% and best values of 63% have been realized. The optical power of the guided light at each output port of the coupler exceeds 1 mW
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.