A semiconductor laser element capable of reducing the contact resistance and the thermal resistance and realizing a high reliability is provided. An example of an area of application of the present invention is enterprise web applications that are installed on a server in a customer network. The corners are projected in the direction orthogonal to the one end of each of the transmitter and receiver cases, and the hinge mechanism is installed between the projected corners of the cases. A second embodiment includes a plurality of inner skirts that alternately attach distal to and proximate from the frangible links.