In the framework of the EU-funded research project “FABULOUS,” we experimentally demonstrate an innovative FDMA-PON architecture whose upstream transmission is based on a reflective Mach-Zehnder modulator. By a careful optimization of electrical spectrum allocation, semiconductor optical amplifier biasing point, and modulation index, we upgrade previous results over similar architectures, significantly increasing the achievable optical distribution network loss. We demonstrate an overall upstream capacity of 32 Gb/s per wavelength over 37 km of installed fiber and 31 dB loss.

Frequency dissemination over optical fiber links relies on measuring the phase of fiber-delivered lasers. Phase is extracted from optical beatnotes and the detection fails in case of beatnotes fading due to polarization changes, which strongly limit the reliability and robustness of the dissemination chain. We propose a new method that overcomes this issue, based on a dual-polarization coherent receiver and a dedicated signal processing that we developed on a field programmable gated array. Our method allowed analysis of polarization-induced phase noise from a theoretical and experimental point of view and endless tracking of the optical phase. This removes a major obstacle in the use of optical links for those physics experiments where long measurement times and high reliability are required.

We report about the final results of the FABULOUS European project, demonstrating the feasibility of real-time Ethernet transmission on a self-coherent reflective Passive Optical Network, using an Optical Network Unit whose main optical functions are performed by a silicon-photonics device; 500 Mbps per user with a power budget of 24 dB in offline processing and 21 dB in real-time is shown. We also report details about the packaging process and the special technique developed for the flip-chipping of a CMOS electrical driver, used for driving the ONU with low voltage, onto a Silicon Mach Zehnder Modulator.

In this paper, we present the most comprehensive system demonstrator realized so far inside the FABULOUS project, an EU 7th Framework Program European research project. The architecture proposed in FABULOUS is based on frequency division multiplexed PON and uses a self-coherent and reflective approach in the upstream. The demonstration presented in this paper uses discrete optoelectronics components. We will show system experiments realized with five active optical network units, together with the emulation of other 27 ONUs ASE noise, demonstrating that such network is capable of an upstream transmission of 32 Gb/s over 40 km of dark fiber and an attenuation of 31 dB, in compliancy with ODN class N2 of the latest PON standards. In addition, we will demonstrate, thanks to the flexibility of frequency multiplexing, that the network can adapt its performances to the link conditions, achieving higher aggregate bit rates or higher losses depending on the link quality that every user in the network experiences. To conclude, we will investigate on the feasibility of the required digital signal processing onto FPGA or ASIC platforms.

The advent of optical frequency standards with ultimate uncertainties in the low $1\times {10}^{-18}$ requires femtosecond frequency combs to support a similar level of resolution in the spectral transfer and the computation of optical frequency ratios. The related experimental challenges grow together with the number of optical frequencies to be measured simultaneously, as in many cases the comb’s optical power does not allow reliable beatnote counting or tracking in all the spectral regions of interest. Here we describe the use of a track-and-hold amplifier to implement the gated detection, a previously proposed technique for improving the signal-to-noise ratio of the beatnote between a low-power tooth of the frequency comb and a continuous-wave laser. We demonstrate a 12-dB improvement in the signal-to-noise ratio of beatnotes involving a broadband-spanning optical comb as compared to traditional detection schemes. Our approach enables reliable and cycle-slip-free spectral purity transfer and reduces the system sensitivity to power drops in the comb spectrum. Being based on a single chip, it is robust, versatile, and easily embedded in more complex experimental schemes.

We present the first experimental demonstration of a Gigabit Ethernet transmission system capable of reaching 50m on A4a.2 POF (standard 1mm PMMA Step-Index Plastic Optical Fiber) with high system margin (6.5 dB) under real Ethernet traffic flowing between two workstations.