150 Gbps multi-wavelength FSO transmission with 25-GHz ITU-T grid in the mid-infrared region

Abstract

The 3∼5 µm mid-infrared (mid-IR) light has several exceptional benefits in the case of adverse atmospheric conditions compared to the 1.5 µm band, so it is a promising candidate for optical carriers for free-space communication (FSO) through atmospheric channels. However, the transmission capacity in the mid-IR band is constrained in the lower range due to the immaturity of its devices. In this work, to replicate the 1.5 µm band dense wavelength division multiplexing (DWDM) technology to the 3 µm band for high-capacity transmission, we demonstrate a 12-channel 150 Gbps FSO transmission in the 3 µm band based on our developed mid-IR transmitter and receiver modules. These modules enable wavelength conversion between the 1.5 µm and 3 µm bands based on the effect of difference-frequency generation (DFG). The mid-IR transmitter effectively generates up to 12 optical channels ranging from 3.5768 µm to 3.5885 µm with a power of 6.6 dBm, and each channel carries 12.5 Gbps binary phase shift keying (BPSK) modulated data. The mid-IR receiver regenerates the 1.5 µm band DWDM signal with a power of -32.1 dBm. Relevant results of regenerated signal demodulation have been collected in detail, including bit error ratio (BER), constellation diagram, and eye diagram. The power penalties of the 6th to 8th channels selected from the regenerated signal are lower than 2.2 dB compared with back-to-back (BTB) DWDM signal at a bit error ratio (BER) of 1E-6, and other channels can also achieve good transmission quality. It is expected to further push the data capacity to the terabit-per-second level by adding more 1.5 µm band laser sources and using wider-bandwidth chirped nonlinear crystals.

Experimental Investigation of Laser Damage Limit for ZPG Infrared Single Crystal Using Deep Magnetorheological Polishing of Working Surfaces

“…Pulsed-periodic sources of powerful coherent mid-infrared (IR) radiation are widely used in many areas of science and technology. In particular, frequency converters operating in the 3.5-5.0 µm wavelength range and in the 8.0 µm region are promising for organizing optical communication in the atmosphere within the framework of global 6G information transmission systems [1]. Sources of coherent mid-IR radiation are also used for processing materials (glasses, ceramics, or semiconductors) by scribbling and thermal cracking [2,3] in medicine, including in the diagnosis of diseases [4][5][6].…”