Abstract
Chip-scale frequency comb generators have the potential to become key building blocks of compact wavelength-division multiplexing (WDM) transceivers in future metropolitan or campus-area networks. Among the various comb generator concepts, quantum-dash (QD) mode-locked laser diodes (MLLD) stand out as a particularly promising option, combining small footprint with simple operation by a DC current and offering flat broadband comb spectra. However, the data transmission performance achieved with QD-MLLD was so far limited by strong phase noise of the individual comb tones, restricting experiments to rather simple modulation formats such as quadrature phase shift keying (QPSK) or requiring hardware-based compensation schemes. Here we demonstrate that these limitations can be overcome by digital symbol-wise blind phase search (BPS) techniques, avoiding any hardware-based phase-noise compensation. We demonstrate 16QAM dual-polarization WDM transmission on 38 channels at an aggregate net data rate of 10.68 Tbit/s over 75 km of standard single-mode fiber. To the best of our knowledge, this corresponds to the highest data rate achieved through a DC-driven chip-scale comb generator without any hardware-based phase-noise reduction schemes.
Highlights
With the explosive growth of data rates across all network levels [1], wavelength-division multiplexing (WDM) schemes are becoming increasingly important for short transmission links that connect, e.g., data centers across metropolitan or campus-area networks
According to [23], mode-locking in QD-mode-locked laser diodes (MLLD) can be attributed to mutual sideband injection due to selfinduced carrier density modulations at the FSR frequency, similar to actively mode locked laser diodes, but induced by the signal generated from the beating among the laser cavity modes rather than by an external radio frequency (RF) source
We show that symbolwise blind phase search (BPS) algorithm [22], relying on continuous feed-forward estimation and correction of the instantaneous phase difference between the local oscillator (LO) tone and the carrier, substantially improves the transmission performance of the QD-MLLD and enables the use of 16-state quadrature amplitude modulation (16QAM) signaling, see Fig. 3
Summary
With the explosive growth of data rates across all network levels [1], wavelength-division multiplexing (WDM) schemes are becoming increasingly important for short transmission links that connect, e.g., data centers across metropolitan or campus-area networks. The highest performance was achieved by exploiting Kerr nonlinearities in integrated optical waveguides, either for spectral broadening of initially narrowband frequency combs [7] or for Kerr comb generation in high-Q microresonators [4-6] While these approaches allow to generate hundreds of spectral lines distributed over bandwidths of 10 THz or more, the underlying setups are rather complex, require high pump power levels along with delicate operation procedures, and still comprise discrete components such as fiber amplifiers or external light sources. Other approaches to chipscale comb generators rely on gain switching of injection-locked DFB lasers [9-11], which may be integrated into chip-scale packages with all peripheral components but suffer from the rather small bandwidth of the overall comb, which typically spans less than 500 GHz [11] These limitations may be overcome by so-called quantum-dash (QD) mode-locked laser-diodes (MLLD) [12-21]. Our results combined with the robustness and the ease of operating QD-MLLD show the great potential of such devices as light sources for highly scalable WDM transceivers
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
