preamp ic 18 the present invention is not limited to such a configuration for example in the case of an optical transceiver module in which capacitors and ics are not disposed on the stem 10 only the photodetector 16 and the components around it may be covered with the shielding member 26 further although the diffraction grating 34 shown in fig2 has been described as having a diffraction angle of 10 degrees at wavelength u03bb 2 it may have any diffraction angle less than 90 degrees as described above which still results in reduced component mounting space a second embodiment of the present invention provides an optical transceiver module that has smaller component mounting space than the optical transceiver module of the first embodiment fig3 shows an optical transceiver module of the present embodiment this optical transceiver module differs from that of the first embodiment in that it includes a stem 38 and a shielding member 40 instead of the stem 10 and the shielding member 26 the stem 38 is a grounded metal member and has upwardly protruding stem protrusions 13 as shown in fig3 b each stem protrusion 13 surrounds a respective light emitting device power supply pin 14 and has a height equal to or greater than the thickness of the shielding member this means that the circumferential surfaces of the light emitting device power supply pins 14 are covered with a thicker metal.