TE- and TM-coupling coefficients in multiquantum well distributed feedback lasers

Transverse-electric (TE)- and transverse-magnetic (TM)-coupling coefficients for typical 1.55- mu m InGaAs/InP buried-heterostructure (BH) multiquantum-well (MQW) distributed-feedback (DFB) lasers are calculated as a function of waveguide and grating parameters using coupled-mode theory. It is shown that the TE- and TM-coupling coefficients become maximum at a certain number of wells; that number is smaller for TE modes than for TM modes, and increases as the BH stripe width decreases. The difference between the TE- and TM-coupling coefficients decreases as the number of wells increases. There exists a value of the thickness of the grating layer which maximizes the coupling coefficient.<
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