Fig. 1. (a) Schematic diagram of the proposed approach for wideband multipath SIC. LD, laser diode; Tx, transmitter; Rx, receiver; GC, grating coupler; PM, phase modulator; ES, electrical splitter; OBPF, optical bandpass filter; EDFA, erodium-doped fiber amplifier; WDM, wavelength division multiplexer; PC, polarization controller; PBS, polarization beam splitter; PBC, polarization beam combiner; τ, variable optical delay line; α, variable optical attenuator; PD, photodetector. (b) The simplified optical spectra corresponding to nodes (I)–(VII) in (a).

Fig. 2. (a) Photograph of the SPM chip. (b) The packaged external view of the SPM chip.

Fig. 3. Experimental setup of the proposed approach for wideband multipath SIC. ESA, electrical spectrum analyzer; AWG, arbitrary waveform generator; EC, electrical combiner; MOTDL, multipath optical tunable delay line; DWDM, dense wavelength division multiplexer.

Fig. 4. Measured optical spectra of the optical signals after the SPM chip, OBPF, and EDFA.

Fig. 5. Measured wideband multipath SIC depths when cancellation paths are 1 (blue solid line) and 2 (red dashed line).

Fig. 6. Measured electrical spectra of a single-tone signal for multipath SIC at the carrier frequency of 9 GHz when the cancellation paths are 0 (blue solid curve), 1 (red dashed curve), and 2 (yellow dotted curve).

Fig. 7. Measured electrical spectra of a wideband signal for multipath SIC when the frequency is 9 GHz with cancellation paths are 0 (blue solid curve), 1 (red dashed curve), and 2 (yellow dotted curve) when the bandwidths are (a) 500 MHz and (b) 1 GHz.

Fig. 8. Measured electrical spectra of a wideband signal for multipath SIC when the frequencies of the SI signal and SOI are 9 GHz with cancellation paths are 0 (blue solid curve), 1 (red dashed curve), and 2 (yellow dotted curve) when the bandwidths are (a) 500 MHz, and (b) 1 GHz.