An efficient combining technique to analyze the performance of non-ideal ASK optical systems

• Propose a new method to detect optical signals in the presence of laser phase noise.
• This technique has the ability to reduce the SNR gain penalty.
• The new method is superior to the envelope detection method by at least 1 dB.
• Glass pore contact angle varies with liquid surface tension and chemical structure.
• The number of photoelectrons required in ideal systems to obtain a certain BER can be maintained.

In this paper, we propose a new method to detect binary optical homodyne and heterodyne amplitude shift keying (ASK) signals in the presence of laser phase noise and receiver shot noise. This method relies on an efficient least square (LS) algorithm to mitigate the negative effects of phase noise error. The error rate performance of non-ideal ASK systems is investigated under LS detection and the signal-to-noise ratio (SNR) gain penalty of heterodyne system over homodyne system is observed. For design purposes, we also provide tabulated results for the number of required photoelectrons to achieve a certain error rate level for the system under investigation. To show the effectiveness of the proposed LS combining technique we compare our results for non-ideal systems with some previous results in the literature. The numerical results obtained through this work show that LS technique has the ability to reduce the SNR gain penalty caused by the lasers phase error, and hence, can be used in any wire-line or wireless coherent systems that suffer from imperfect (non-ideal) phase recovery.