New high-resolution positive and negative photoresist method for ?/4-shifted DFB lasers |
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| Authors: | Okai M Tusji S Hirao M Matsumura H |
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| Affiliation: | Hitachi Ltd., Central Research Laboratory, Kokubunji, Japan; |
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| Abstract: | High-resolution positive and negative photoresists were used to fabricate ?/4-phase-shifted corrugations by holographic exposure. To avoid mixing these photoresists, cyclised polyisoprene was used as a midlayer. The shape and depth of the corrugations on the positive and negative photoresist regions were almost the same. Single-mode operation at the Bragg wavelength was confirmed in lasers with the corrugation. |
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