Exploration of Four-Channel Coherent Optical Chaotic Secure Communication with the Rate of 400 Gb/s Using Photonic Reservoir Computing Based on Quantum Dot Spin-VCSELs
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsBy using four simultaneous photonic reservoir computers in tandem with four coherent demodulation units, the authors simulated and explored four-channel coherent optical chaotic secure communication (COCSC). The theory and results on four-channel COCSC are interested. The manuscript can be published when some issues need to be further clarified.
1. How many are the rate of these encoded messages QPSK, 4QAM, 8QAM and 16QAM?
2. The authors should present the eye-diagram of decoded message of QPSK, 4QAM, 8QAM and 16QAM.
3. In Fig.2, whether QPSK, 4QAM, 8QAM and 16QAM are optical signal or electronic signal. If they are optical signal, please further clarify these messages.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe paper introduces a four-channel coherent optical chaotic secure communication system. By using QD spin-VCSEL and photonic reservoirs, the COCSC successfully achieves wideband chaos synchronization, which allows COCSC system boasts a 4x100 GHz capacity. The paper is clearly written and coherent. The architecture and the analyses for it look promising. However, there are few minor concerns need to be addressed:
1. In line 72, the text identifies new challenges associated with COCSC but fails to specify what these challenges are. Furthermore, in line 79, the suitability of QD-Spin-VCSELs for "this purpose" is mentioned without explaining the intended purpose. Clarification of the specific challenges in COCSC and how QD-Spin-VCSELs address these challenges could provide a more coherent connection and justification.
2. In the description of the simulation experiment setup (line 201), the chaotic hidden signals are represented as EGx(t) + S1(t), but there is no explanation of the origin of S1(t). If S1(t) is a result of the nonlinear dynamics inherent to QD spin-VCSEL, this should be explicitly pointed out here. Could the author provide more details on the generation and role of S1(t) in the context of the chaotic signals?
3. In figure 3, the font size used for red text in the figure is too small to read. Could the author increase the font size to make it easier to read.
4. The author shows the BER result about decoded messages and their associated baseband signals. The result of BER is around 10-2, which indicates a relatively poor signal quality. However, from the eye diagram of your signal, the eye is very clean suggesting a higher quality signal with minimal noise, which should have a better BER compared to 10-2. Could the author explain why the result of BER and eye diagram shows different signal quality?
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
