Dense WDM transmission at 2  μm enabled by an arrayed waveguide grating

Abstract

We show, for the first time, dense WDM (8×20 Gbit/s) transmission at 2 μm enabled by advanced modulation formats (4-ASK Fast-OFDM) and the development of key components, including a new arrayed waveguide grating (AWGr) at 2 μm. The AWGr shows -12.8±1.78 dB of excess loss with an 18-dB extinction ratio and a thermal tunability of 0.108 nm/°C.

Key enabling technologies for optical communications at 2000 nm

“…This scheme enables a simultaneous comparison between our previously reported result at 100 GHz spacing [16] and emulating a 50 GHz spacing scenario. The bias and drive signals of both lasers were optimized in order to investigate the impact of the 50 GHz contribution.…”

“…[23]. Selecting each DWDM channel at the receiver is not trivial at 2000 nm, as currently available tunable bandpass filters have a 3 dB BW of ∼1.6 nm (Agiltron Inc. FOTF 043121333), and the in-house AWG used here hasve a side-mode suppression ratio of ∼18 dB [16]. Thus, by cascading both devices, channel isolation improves (for 100 GHz spacing) to ∼26 dB [23].…”

“…We have shown previously that the first generation devices were capable of delivering DWDM with 100 GHz spaced channels and a total capacity of 100 Gbit/s [16]. Capacities reaching 30 Gbit/s were achieved with the aid of advanced modulation formats that still use direct detection [17].…”

Demonstration of High-Speed Optical Transmission at 2 µm in Titanium Dioxide Waveguides

“…Recently, the 2 µm spectral region has been suggested as a new transmission window [5], benefiting from the emergence of thulium-doped fiber amplifiers (TDFA) with broadband and high gain spanning from 1900 to 2100 nm [6]. This has stimulated studies of dedicated photonic components such as InP-based modulators [7,8] or arrayed waveguide gratings [9]. High bit rate communications over distances exceeding one hundred meters have already been successfully demonstrated [10][11][12][13] in low-loss hollow core bandgap photonic fibers designed to present minimal losses around 2000 nm [14] or in solid-core single mode fibers [15].…”

High gain holmium-doped fibre amplifiers

“…Another application of 2 µm sources that has recently attracted attention is optical fibre communications [5][6][7][8][9][10]. This interest is being driven by demonstrations of low-loss hollowcore photonic band-gap fibers (HC-PBGFs) which offer a transmission medium possessing ultra-low nonlinearity, low latency, and with the potential for a broad ultra-low loss window at wavelengths around 2 µm [11].…”