Abstract-Single-mode 1.5-µm InP-based vertical-cavity surface-emitting lasers (VCSELs) with a 1.5-λ long semiconductor cavity and two dielectric distributed Bragg reflectors (DBRs) are presented. The electrical, thermal and optical characteristics are studied as a function of tunnel junction diameter and for different temperatures ranging from -10°C up to 65°C. Small-signal modulation bandwidths in excess of 21 GHz at room temperature are demonstrated for a DC power consumption below 10 mW. In this paper, the superior dynamic characteristics of these VCSELs are shown by demonstrating error-free operation at data rates up to 50 Gb/s in back-to-back configuration by non-return-to-zero modulation and without any equalization. Neither forward error correction nor digital signal processing were required.

Abstract-High speed optical interconnects require low-power compact electro-optical transmit modules comprising driver circuits and optical modulators. This paper presents a low power 56 Gb/s non-return-to-zero CMOS inverter based driver in 28 nm fully depleted silicon-on-insulator CMOS driving a 46 GHz silicon photonic microring modulator. The driver delivers 1 Vpp to the microring modulator from a 75 mVpp input while only consuming 40 mW (710 fJ/bit at 56 Gb/s). The realized transmitter shows 4 dB extinction ratio when running of a 1 V supply voltage. Transmission experiments up to 2 km of single mode fiber show a bit-error-ratio less than 1 · 10

Long-wavelength vertical-cavity surface-emitting lasers (LW-VCSELs) with emission wavelength in the 1.3-µm region for intensity modulation (IM)/direct detection optical transmissions enable longer fiber reach compared to C-band VCSELs, thanks to the extremely low chromatic dispersion impact at that wavelength. A lot of effort has been recently dedicated to novel cavity designs in order to enhance LW-VCSELs' modulation bandwidth to allow higher data rates. Another approach to further improve VCSEL-based IM speed consists of making use of dedicated driver circuits implementing feedforward equalization (FFE). In this paper, we present a transmitter assembly incorporating a fourchannel 0.13-µm SiGe driver circuit wire-bonded to a novel dual 1.3-µm VCSEL array. The short-cavity indium phosphide buried tunnel junction VCSEL design minimizes both the photon lifetime and the device parasitic currents. The integrated driver circuit requires 2.5-V supply voltage only due to the implementation of a pseudobalanced regulator; it includes a two-tap asymmetric FFE, where magnitude, sign, relative delay, and pulse width distortion of the taps can be modified. Through the proposed transmitter, standard single-mode fiber reach of 20 and 4.5 km, respectively, for 28-and 40-Gb/s data rate has been demonstrated with stateof-the-art power consumption. Transmitter performance has been analyzed through pseudorandom bit sequences of both 2 7 −1 and 2 31 −1 length, and the additional benefit due to the use of the driver circuit has been discussed in detail. A final comparison with stateof-the-art VCSEL drivers is also includedt.

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Abstract-Conventional 850 nm multi-mode fiber (MMF) links deployed in warehouse-scale data centers will be limited by modal dispersion beyond 10 Gb/s when covering distances up to 1 km. This can be resolved by opting for a single-mode fiber (SMF), but typically requires the use of power-hungry edgeemitting lasers. We investigate the feasibility of a high-efficiency SMF link by reporting a 0.13 µm SiGe BiCMOS laser diode driver optimized for long-wavelength vertical-cavity surfaceemitting lasers (VCSEL). Bit-error rate experiments at 28 Gb/s and 40 Gb/s up to 1 km of SMF reveal that four-level pulse amplitude modulation (PAM-4) can compete with non-returnto-zero (NRZ) in terms of energy efficiency and scalability. With 9.4 pJ/bit, the presented transmitter paves the way for VCSELbased SMF links in data centers.

The soaring demand for higher speeds in datacenters to address the relentless growth of the global IP traffic places optical interconnects in the spotlight. In this manuscript, we present a high-speed optical transceiver for intra-datacenter connectivity. The transceiver is based on single-mode, single-polarization high-speed vertical-cavity surface-emitting lasers (VCSELs), a VCSEL driver chip, and a linear receiver. Following a step-by-step approach, we present the architectures, assembly processes, and experimental results from the different modules. More specifically, we demonstrate (1) a data transmission experiment at 80 Gb/s using PAM-4 (four-level Pulse Amplitude Modulation) modulation for a reach of up to 500 m by employing a single-mode VCSEL module, and (2) a full-link experiment proving up to 64 Gb/s per lane capacity using PAM-4 signaling of the VCSEL-based optical transceiver test vehicles in back-to-back configuration and up to 56 Gb/s for 500 m and 2 km transmission distances. The acquired experimental results verify the suitability of the optical transceiver for intra-datacenter interconnects’ applications.

Abstract-Through co-design of a dual SiGe transimpedance amplifier and an integrated silicon photonic circuit, we realized for the first time an ultra-compact and low-power silicon singlepolarization coherent receiver operating at 40 GBaud. A biterror rate of less than 3.8 × 10 -3 was obtained for an optical signal-to-noise ratio of 14 dB for QPSK modulation (80 Gb/s), and 26.5 dB for 16-QAM (160 Gb/s). We also demonstrate robust performance of the receiver over temperature and wavelength.

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