| 摘要 |
PROBLEM TO BE SOLVED: To obtain a good signal and also to miniaturize the optical pickup in reducing its weight without increasing the number of parts by making an amplitude of light coupled with a waveguide symmetrical to an optical axis of a beam incident upon a waveguide element. SOLUTION: An amplitude distribution function of an outgoing beam of a prism coupler 106 is approximately symmetrical in the optical pickup by making a radiation damping coefft. α variable. In this case, the outgoing beam amplitude distribution function G (z) is approximately symmetrically formed as shown in the figure. Thus, since the amplitude of the light coupled with the waveguide is made symmetrically to the optical axis by the structure of the prism coupler 106 as a light coupling means, the rise and the fall of a read signal waveform are also symmetrically formed, and hence the good signal can be obtained. |
