No abstract

No abstract

No abstract

This letter presents a low-power transimpedance amplifier (TIA), supporting both 25 and 40-Gb/s communication. It exhibits an optical modulation amplitude sensitivity of −10.6 dBm at 25 Gb/s and −6.4 dBm at 40 Gb/s using a photodiode with a responsivity of 0.55 A/W. The TIA consumes 158 mW from a 2.5 V supply and was manufactured in a 0.13-µm SiGe BiCMOS process. Compared with the state of the art, the presented TIA exhibits a similar sensitivity (at both 25 and 40 Gb/s), while exhibiting a low power consumption for the 40-Gb/s operation. IndexTerms-Transimpedance amplifier (TIA), SiGe BiCMOS.

No abstract

All-digital radio-over-fiber (RoF) transmission has attracted a significant amount of interest in digital-centric systems or centralized networks because it greatly simplifies the front-end hardware by using digital processing. The sigma-delta modulator (SDM)-based all-digital RoF approach pushes the digital signal processing as far as possible into the transmit chain. We present a real-time 100-GS/s fourth-order single-bit SDM for all-digital RoF transmission in the high-frequency band without the aid of analog/optical up-conversion. This is the fastest sigma-delta modulator reported and this is also the first real-time demonstration of sigma-delta-modulated RoF in the frequency band above 24 GHz. 4.68 Gb/s (2.34 Gb/s) 64-QAM is transported over 10-km standard single-mode fiber in the C-band with 6.46% (4.73%) error vector magnitude and 3.13 Gb/s 256-QAM can be even received in an optical back-to-back configuration. The carrier frequency can be digitally tuned at run-time, covering a wide frequency range from 22.75 to 27.5 GHz. Besides, this high-speed sigma-delta modulator introduces less than 1 µs latency in the transmit chain. Its all-digital nature enables network virtualization, making the transmitter compatible with different existing standards. The prominent performance corroborates the strong competitiveness of this SDMbased RoF approach in high-frequency RoF 5G communication.

No abstract

We present an InP-on-Si DFB laser integrated with electro-absorption modulators on each side, using a single epitaxial structure for laser and modulators. Two electrically isolated tapers couple the light to the Si waveguide, while simultaneously acting as modulators.