| 摘要 |
PURPOSE: To reduce crystal deformation in a part where the core layer of a laser beam diameter conversion waveguide passage gradually becomes thin so as to improve the reliability. CONSTITUTION: This device is provided integrally with a laser beam generating area 51 and laser beam diameter conversion waveguide passage 52. The passage 52 is provided with a thickness gradually-decreasing part 43a constituting part of a core layer 54, upper and lower clad layers 56 and 55, a propagation constant decreasing emphasis layer 57 between the layer 54 and lower clad layer 55, and a propagation constant decreasing emphasis layer 58 between the layer 54 and upper clad layer 55. The layers 57 and 58 have a lower refraction index h12 than those n11 of the layers 55 and 56. The layers 57 and 58 act so as to decrease the propagation constant. Thus, the relative thickness t11 /t10 of the part 54a is 0.7, which is larger compared with the conventional one. |
