High-Capacity Directly Modulated Optical Transmitter for 2-μm Spectral Region

Abstract

Abstract-The 2-µm wave band is emerging as a potential new window for optical telecommunications with several distinct advantages over the traditional 1.55µm region. First of all, the Hollow-Core Photonic Band Gap Fiber (HC-PBGF) is an emerging transmission fiber candidate with ultra-low nonlinearity and lowest latency (0.3% slower than light propagating in vacuum) that has its minimum loss within the 2-µm wavelength band. Secondly, the Thulium-doped fiber amplifier that operates in this spectral region provides significantly more bandwidth than the Erbium-doped fiber amplifier. In this paper we demonstrate a single-channel 2-µm transmitter capable of delivering >52 Gbit/s data signals, which is twice the capacity previously-demonstrated. To achieve this we employ discrete multi-tone (DMT) modulation via direct current modulation of a Fabry-Perot semiconductor laser. The 4.4-GHz modulation bandwidth of the laser is enhanced by optical injection locking, providing up to 11 GHz modulation bandwidth. Transmission over 500-m and 3.8-km samples of HC-PBGF is demonstrated.

Demonstration of an 11km Hollow Core Photonic Bandgap Fiber for Broadband Low-latency Data Transmission

“…2c we plot the quantity lengthBW/loss as a figure of merit providing a visual indication of how the different fibers compare in terms of length, transmission bandwidth and loss. The HC-PBGF in this work provides a 20% increase in BW over the previous SOTA and a 3 increase in length as compared to our recent result [19].…”

High Capacity, Low Latency Data Transmission Using Hollow Core-Photonic Bandgap Fibers

“…The use of the core tube increased the fiber yield and also through careful design, enabled fabrication of a final fiber with a record wide operating bandwidth. Two key highlights of this work are a 3.85 km length operating at 2 µm [15] and an 11 km length operating at 1.55 µm [16]; representing an order of magnitude improvement on the previous state-of-the-art.…”

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].…”

“…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]. The transmission loss of HC-PBGF is currently ~2.5 dB/km at 2 µm [5], which is already sufficiently low for certain niche short haul applications. In order to realize an optical communications system, high quality optical amplifiers are indispensable.…”