| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a wavelength sensing element capable of actualizing a noncritical phase matching in a wavelength range in which a noncritical phase matching can not be actualized by a wavelength sensing element using a GdYCOB single crystal. SOLUTION: This wavelength sensing element is provided with an oxyborate single crystal containing a first element being a rare earth element. The ion radius of the first element is smaller than those of gadolinium and yttrium when compared in the same coordination number. The first element preferably contains two or more kinds of elements. A wavelength on which a noncritical phase matching is actualized is sometime controlled by the composition ratio of the two or more kinds of the elements.</p> |
