| 摘要 |
PURPOSE: To make possible to realize difference frequency generation(DFG) or sum frequency generation(SFG) with good conversion efficiency by optimizing an element length. CONSTITUTION: A first layer 12 and a second layer 14 consisting of nonlinear crystals varying in refractive index or second order nonlinear constant satisfy equation I:Δk1 l1 =Δk2 l2 =(2m+1)π(in equation 1,Δk1 ,Δk2 respectively denote the phase mismatching quantity of the first layer 12 and the second layer 14; l1 , l2 denote the lengths of the first layer 12 and the second layer 14 along the propagation directions of a signal lightλs and a pumping lightλp ; (m) demotes and integer), and the element lengths along the propagation directions of the signal lightλs and pumping lightλp are the lengths at which the EG(NΛ) in the matrix equation shown attains the maximal length. In the equation, EG(NΛ) denotes the electric field intensity of the converted light at the output end of the conversion element; ES*(NΛ) is the conjugate of the electric field intensity of the signal light at the output end of the conversion element;Λis a period where it can be expressed byΛ=l1 =l2 ; N denotes the number of the periods in the conversion element; p1 , p2 denote phase peaks; C11 , C12 , C21 , C22 respectively denote optical parameters.
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