Package with locking mechanism and optical transceiver

An optical transceiver, comprising:

• a transceiver main body insertable into a cage formed in a host instrument;
• a transceiver head integrated with the package main body, the transceiver head protruding from the host instrument when the transceiver main body is inserted into the cage;
• a latch member attached to the transceiver main body, wherein the latch member restricts detachment of the transceiver main body from the cage when it is inserted into a hole formed in a wall of the cage and it is at a contact plane thereof in contact with a front edge of the hole while protruding from a predetermined face of the transceiver main body;
• and
• a revolving shaft disposed perpendicular to a direction in which the transceiver main body is inserted into and detached from the cage, the latch member being pivoted on the revolving shaft,
• wherein the revolving shaft is disposed near the contact plane of the latch member.