An optical connector comprises a first block having a channel for accommodating a first set of optical cables and a second block having a channel for accommodating a second set of optical cables. Each passage includes a fastening recess, and the fastening recess includes a flared upper portion. When the devices can seize each other within that time period, the communication channel is established. Methods of using the device are disclosed. Further, it may be configured that the slider presses the pressing portions to thereby displace the contact portions in directions away from the connection object. The power amplifier circuit controls output power in accordance with input power that is varied while a gain of the power amplifier circuit is being fixed by either a bias current or a bias voltage supplied from the bias control circuit.