Browse Prior Art Database

Zero Mode Diode Laser

IP.com Disclosure Number: IPCOM000080894D
Original Publication Date: 1974-Feb-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Zory, PS: AUTHOR

Abstract

One of the main difficulties in utilizing semiconductor laser diodes in systems applications, is due to the fact that "Wing" type modes (high-order TE modes), as shown in Fig. 1, predominate. TE-o or TM-o as shown in Fig. 2 would be preferred. The reason that "Wing" modes predominate is due primarily to the fact that they have more feedback because, effectively, they are incident on the end faces at larger angles of incidence than zero modes, and the Fresnel reflection coefficient for TE waves increases with angle of incidence.

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Zero Mode Diode Laser

One of the main difficulties in utilizing semiconductor laser diodes in systems applications, is due to the fact that "Wing" type modes (high-order TE modes), as shown in Fig. 1, predominate. TE-o or TM-o as shown in Fig. 2 would be preferred. The reason that "Wing" modes predominate is due primarily to the fact that they have more feedback because, effectively, they are incident on the end faces at larger angles of incidence than zero modes, and the Fresnel reflection coefficient for TE waves increases with angle of incidence.

A solution to the problem could be achieved using the structure shown in Fig.
3. Mirror feedback from the end faces is not used, but distributed feedback from the side of the waveguide is employed. The structure of Fig. 3 can be used to obtain transverse mode selectivity.

For a given thickness modulation, the dominant mode will be TM-o provided the length of the modulated region is long enough. Or, alternatively, for a given length device, it should be possible to design a thickness modulation such that TE-o or TM-o is the lowest threshold laser mode. Detailed calculations for a given structure are difficult. However, it has been demonstrated that the effect exists by using lasing dyes in thickness modulated waveguides.

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