| 摘要 |
PROBLEM TO BE SOLVED: To provide a wavelength multiplexer/demultiplexer which is so de signed that transmittance characteristics may be independent of temperature. SOLUTION: The wavelength multiplexer/demultiplexer has a first polarized light separating and synthesizing means, a birefringence crystal plate constituted by lamenting two kinds of birefringence crystal (a) and (b) and a second polarized light separating and synthesizing means arranged on the optical path in this order, and a ratioγof thickness La of the birefringence crystal a to thickness Lb of the birefringence crystal b is given by following formula;γ=La/Lb=|δ|andδ=-[αa(nao -nae )+(naTo -NaTe )]/[αb (nbo -nbe )+(nbTo -- nbTe )] whereαa, nao , nae , naTo , and NaTe are representative of the linear expansion coefficient, the refractive index for ordinary rays, the refractive index for extraordinary rays, the temperature dependence coefficient of the refractive index for ordinary rays, and the temperature dependence coefficient of the refractive index for extraordinary rays in the birefringence crystal a andαb, nbo , nbe , nbTo , and nbTe are representative of those in the birefringence crystal b.
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