An assembly with optical gain assisted optical transposer is provided. The optical transposer which optically couples a fibre array unit and a photonic integrated circuit. The optical transposer includes one or more optical gain elements which are configured to provide optical compensation, for example optical gain to mitigate optical losses associated with multistage photonic integrated devices. According to some embodiments, the optical gain element is a semiconductor optical amplifier (SOA). According to some embodiments the photonic integrated circuit is a SiPh PIC.