Optical module with electrically isolated stem and cap

An optical sub-assembly installed in an optical transceiver with a housing providing a frame ground and a circuit board providing a signal ground, comprising:

• an optical module including a stem, a cap, a semiconductor optical device, and a plurality of lead pins, said stem comprising a center portion, a peripheral portion and an insulator interposed between said center portion and said peripheral portion, said center portion mounting said semiconductor optical device, said peripheral portion holding said cap, at least one of said lead pins being directly and electrically connected to said center portion in one end thereof and to said signal ground on said circuit board;
• a sleeve member configured to receive an external optical connector with an optical fiber to be optically coupled with said semiconductor optical device, said sleeve member exposing outside of said optical transceiver to receive said optical connector, said sleeve member electrically connected to said frame ground of said housing of said optical transceiver;
• and
• a joint member arranged between said sleeve member and said optical module to optically couple said optical module with said sleeve member,
• wherein said signal ground is electrically isolated from said frame ground.