| 摘要 |
PROBLEM TO BE SOLVED: To decrease a beam diameter. SOLUTION: A tapered waveguide 22 has a waveguide width which is gradually narrower from an incident port to an emitting port. A waveguide 24 having the same waveguide width as that of an emitting port 22b is connected to the emitting port 22b of the tapered waveguide 22. A mode waveguide 26 having a constant waveguide width narrower than that of the waveguide 24 is connected to the other end of the waveguide 24. The waveguide 22 has multimode at the incident port 22a, but has only zeroth mode, primary mode, and secondary mode at the emitting port 22b. The waveguide 24 has only zeroth mode, primary mode, and secondary mode. The waveguide 26 has only zeroth mode. The waveguide width discontinuously changes at the connected portion of the waveguide 24 and the waveguide 26. COPYRIGHT: (C)2003,JPO |
