In a semiconductor lasers using quantum well gain medium, a quantum well stack is mounted in an epi-down configuration. In addition, the apparatus side housing can be fixed into the mounting hole by a stopper and a retainer, so that workability is good as compared with the case of fixing the apparatus side housing by bolt tightening. The outlet is disposed on one side of the computer system. Locking diffractive element sets may be formed in channel waveguides formed in the planar waveguide, or in slab waveguide region of the planar waveguide. A corresponding scene command may be generated and sent to the control device. The issuer responds with an approvaldenial message and, in the latter case, includes the next challenge to be used.