Patent ID: 7907647
Filing Date: 2011-03-15
Classification: H01S

Abstract:
1. An optical element for converting a pump light of prescribed wavelength emitted from a light source into output light of wavelength different from the prescribed wavelength of the light source; the optical element comprising: a first crystal part including KTiOPO a second crystal part including YVO a first selective transmitting film provided on a first surface of the first crystal part at which the pumped light is incident, said first selective transmitting film transmitting the pump light and reflecting a basic light beam emitted from said first crystal part when being pumped by said pump light; a second selective transmitting film provided on a second surface of the second crystal part provided for outputting the output light having the converted wavelength, said second selective transmitting film transmitting the output light and reflecting the basic light beam emitted from said first crystal part; and an adhesive layer disposed between a light-transmitting portion of the first crystal part and a light transmitting portion of the second crystal part such that a second surface of the first crystal part facing the second crystal part is stuck to a first surface of the second crystal part facing the first crystal part, the adhesive layer being formed to a thickness in the range of more than 2 μm and less than or equal to 20 μm, wherein a second surface of the first crystal part and a first surface of the second crystal part opposed to each other through the adhesive layer have coefficients of linear expansion which are different by 5 ppm or more and the surfaces of said first and second crystal parts opposed to each other through the adhesive layer are disposed so as to include crystallographic axes, and the adhesive layer is a cured acrylic adhesive whose glass transition point is 75° C. or lower, the refractive index of the adhesive layer after cure being equal to or greater than 1.49 and less than or equal to 1.52.