Silicon intensity Mach–Zehnder modulator for single lane 100 Gb/s applications

In this paper, a substrate removing technique in a silicon Mach–Zehnder modulator(MZM) is proposed and demonstrated to improve modulation bandwidth. Based on the novel and optimized traveling wave electrodes,the electrode transmission loss is reduced, and the electro-optical group index and 50 Ω impedance matching are improved, simultaneously. A 2 mm long substrate removed silicon MZM with the measured and extrapolated 3 dB electro-optical bandwidth of >50 GHz and 60 GHz at the-8 V bias voltage is designed and fabricated.Open optical eye diagrams of up to 90 GBaud∕s NRZ and 56 GBaud∕s four-level pulse amplitude modulation(PAM-4) are experimentally obtained without additional optical or digital compensations. Based on this silicon MZM, the performance in a short-reach transmission system is further investigated. Single-lane 112 Gb∕s and 128 Gb∕s transmissions over different distances of 1 km, 2 km, and 10 km are experimentally achieved based on this high-speed silicon MZM.

800 Gbit/s transmission over 1 km single-mode fiber using a four-channel silicon photonic transmitter

We demonstrate the optical transmission of an 800 Gbit/s(4×200 Gbit/s)pulse amplitude modulation-4(PAM-4)signal and a 480 Gbit/s(4×120 Gbit/s)on–off-keying(OOK)signal by using a high-bandwidth(BW)silicon photonic(SiP)transmitter with the aid of digital signal processing(DSP).In this transmitter,a four-channel SiP modulator chip is co-packaged with a four-channel driver chip,with a measured 3 dB BW of 40 GHz.DSP is applied in both the transmitter and receiver sides for pre-/post-compensation and bit error rate(BER)calculation.Back-to-back(B2B)BERs of the PAM-4 signal and OOK signal are first measured for each channel of the transmitter with respect to a variety of data rates.Similar BER performance of four channels shows good uniformity of the transmitter between different channels.The BER penalty of the PAM-4 and OOK signals for 500 m and 1 km standard single-mode fiber(SSMF)transmission is then experimentally tested by using one channel of the transmitter.For a 200 Gbit/s PAM-4 signal,the BER is below the hard-decision forward error correction(HD-FEC)threshold for B2B and below the soft-decision FEC(SD-FEC)threshold after 1 km transmission.For a 120 Gbit/s OOK signal,the BER is below SD-FEC threshold for B2B.After 500 m and 1 km transmission,the data rate of the OOK signal shrinks to 119 Gbit/s and 118 Gbit/s with the SD-FEC threshold,respectively.Finally,the 800 Gbit/s PAM-4 signal with 1 km transmission is achieved with the BER of all four channels below the SD-FEC threshold.