Lens unit, optical waveguide device, and optical transmission apparatus

The present invention improves the mechanical strength of a lens in which an optical waveguide provided on a substrate is optically coupled to an optical fiber. A lens unit that optically couples an optical waveguide provided on a substrate and an optical fiber has a lens portion and a holding portion that holds the lens portion, the holding portion has a thick portion along one side surface that is not a surface through which an optical axis passes, and the thickness of the thick portion measured in the direction of the optical axis is greater than the thickness of the other portion of the holding portion. 在将设置于基板的光波导与光纤进行光学耦合的透镜中，提高其机械强度。将设置于基板的光波导与光纤进行光学耦合的透镜单元具有透镜部和保持该透镜部的保持部，保持部沿着不是光轴通过的面的一个侧面具有厚壁部，该厚壁部的沿着光轴的方向测量而得到的厚度比保持部的其他部分大。