Abstract: To provide a cover-changeable cellular telephone which has a sub-display section and automatically adjusts and sets an illumination pattern without involvement of the user's manual adjustment and setting, as well as rendering display quality stable and simplifying operation for changing the cover. A mobile terminal 100 has a cabinet 21, a cover member which is selected from a plurality of types of cover members and attached to the cabinet 21, an illumination section illuminating outside the cabinet 21, a storage section for storing a plurality of types of illumination patterns for the illumination section, and a control section for causing the illumination section to illuminate according to a preset one of the respective illumination patterns. The terminal further has separate identification means provided on the cover member, wherein, when the cover member is attached to the cabinet 21, the control section selects one from the respective illumination patterns assigned to the identification means.

Abstract: A wavelength tunable laser diode comprising a temperature variable heater separated from an active layer by a distance less than the thickness of a compound semiconductor substrate. Because the heater is located very close to the active layer, the response time of temperature change is improved. That in turn widens the tunable range of the laser diode.