“…If the laser is not integrated, both a SMF fiber and a PMF fiber need to be coupled to the PIC simultaneously using, for example, a Si V-groove technique as used by GMMT [28]. If photodetectors are not integrated, such as in the versions made by AT&T [22], NTT [23], CNET [27], and HHI [29], then the output waveguides must be coupled to four fibers, which has not been reported so far, or quad photodetectors need to be packaged together with the hybrid as was reported by HHI [35].…”