In this paper, a multicast optical Ethernet switch based on SOA (Semiconductor Optical Amplifiers) technology with optical output buffers is proposed. Only the header of optical packets is converted to electronic signals to control entire operations of the optical Ethernet switch and the packet payloads can be transparently destined to their output ports. An optical output buffer is designed to queue the packets when more than one incoming packet should reach to the same destination output port. For preserving service packet sequencing and fairness of routing sequence, a priority scheme and a round-robin algorithm are adopted at the optical output buffer. Four methods are used to implement tunable fiber delay modules for the optical output buffers which can handle Ethernet packets with variable bit rate.