A fast, non-invasive calibration method for optical switching delay line based on particle swarm optimization algorithm.

• Realizing simple and non-invasive calibration for optical switching delay lines (OSDLs). • Particle swarm optimization has been used. • The calibration method may be used for OSDL with large bits and other optical devices with similar spectral characteristics. Optical tunable delay line (OTDL) is playing an increasingly significant role in microwave photonic technology. As a representative OTDL, optical switching delay line (OSDL) based on cascaded optical switches has become widespread due to its advantages of large bandwidth, high delay accuracy, and easy control. However, due to fabrication errors, the "through" and "cross" states of all the optical switches in the OSDL must be calibrated by inserting additional components for monitoring, which will inevitably increase the chip size and cost. Therefore, achieving simple and non-invasive calibration of OSDL is very important. Here we proposed a fast and non-invasive calibration method based on spectrum analysis accelerated by particle swarm optimization algorithm (PSO). As a proof-of-concept, we accurately calibrated a 5-Bit silicon OSDL chip by using the proposed method and measured all the delay states and transmission spectra of the OSDL. The results are in good agreement with those obtained by the traditional calibration method with additional optical power monitoring taps. [ABSTRACT FROM AUTHOR]