| 摘要 |
PURPOSE:To manufacture a low distortion distributed feedback type laser for analog modulation which has an ununiform diffraction grating. CONSTITUTION:Electron beam resist 1 is uniformly spread on an InP substrate 2. Electron beam exposure is so performed that the electron beam dosage in the central part is larger than at both of the end portions. In this case, the resist diffraction grating pattern formed in the electron beam resist by proximity effect is low and narrow in the region where the electron beam dosage is large in the central part, and high and wide in the region where the electron beam dosage is small in both of the end portions. In the central part of the diffraction grating, a lambda/4 phase shift 3 is formed. This resist pattern is subjected to dry etching using Cl2 based gas, and transferred on the InP substrate 2. Thus a diffraction grating having an ununiform shape is obtained. A distributed feedback type laser is manufactured by growing in order an optical guide layer, an active layer and a clad layer on the substrate.
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