Practical considerations for fabrication of active AlxGa1-xAs zero-gap directional couplers

James G. Grote; Mohammad A. Karim

doi:10.1117/12.206305

5 April 1995 Practical considerations for fabrication of active Al_xGa_1-xAs zero-gap directional couplers

James G. Grote, Mohammad A. Karim

Proceedings Volume 2400, Optoelectronic Interconnects III; (1995) https://doi.org/10.1117/12.206305
Event: Photonics West '95, 1995, San Jose, CA, United States

Abstract

Al_xGa_1-xAs electro-optic (EO) zero-gap directional couplers (ZGDCs) offer orders of magnitude shorter device lengths than Al_xGa_1-xAs conventional directional couplers (CDCs). Due to the small EO activity of Al_xGa_1-xAs, however, the length of the Al_xGa_1-xAs ZGDC becomes voltage limit dependent. To operate at TTL levels, the interaction channel length of the active Al_xGa_1-xAs ZGDC needs to increase by 25 times over the optimum coupling length of the passive device. For the passive device, the coupling percentage can be easily controlled to within +/- 10% using standard lithographic and growth techniques demonstrating a fabrication tolerant device. The coupling percentage between channels in the longer active devices, however, is much more sensitive to the accuracy of the interaction length which, in turn, is controlled by the accuracy of processing and growth. If one could control the interaction length even to within 1 micrometers , holding the voltage independent phase change to within 1%, the coupling percentage could vary by as much as 45%. Because precise accuracy could not be achieved, the active Al_xGa_{1- x}As ZGDC fabricated for this experiment required a 30% higher switching voltage than optimum. Control of both material growth and fabrication processing is needed unless one is willing to continuously apply a voltage.

Citation Download Citation

James G. Grote and Mohammad A. Karim "Practical considerations for fabrication of active Al_xGa_1-xAs zero-gap directional couplers", Proc. SPIE 2400, Optoelectronic Interconnects III, (5 April 1995); https://doi.org/10.1117/12.206305

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