40 Gb/s WDM Transmission Over 1.15-km HC-PBGF Using an InP-Based Mach-Zehnder Modulator at 2 μm

The 2-μm wavelength range has emerged as a low-loss and low-latency optical transmission window when using hollow-core photonic band gap fiber (HC-PBGF) and high-gain thulium-doped fiber amplifiers (TDFA). Various single and multichannel transmission experiments at these wavelengths have been implemented using directly modulated lasers and LiNbO
₃
-based modulators. Here, we report the transmission performance of an externally modulated 4 × 10 Gb/s NRZ-OOK WDM signal over 1.15 km of low-loss HC-PBGF employing an InP-based Mach-Zehnder modulator (MZM) in the transmitter for the first time. An OSNR of 25 dB on 100-GHz spaced channels is required using a direct detection scheme. Furthermore, we demonstrate the lowest V
_π
InP-based MZM operating at 2 μm by increasing the electro-optical overlap in the optical waveguide. The peak-peak modulation voltage is reduced significantly from 4 to 2.7 V with an electro-optic bandwidth of 9 GHz.