Theoretical and experimental investigation of the compression and reshaping of complex low energy Gain switching sources using a highly nonlinear optical loop mirror

This work presents a theoretical and experimental investigation on the improvement of complex low quality pulses obtained from a pulsed diode laser Gain-Switched (GS) optical sources by using a Highly Nonlinear Optical Loop Mirror (HNOLM) directly coupled to the diode laser source without any previous conditioning of the pulses. First, a design of the HNOLM device is evaluated. The proposed HNOLM is compact, containing 20 m of optical fiber and does not require any intermediate stage to process the pulses. The device is based on the use of a Microstructured Optical Fiber and a Highly Nonlinear Semiconductor Optical Amplifier. An experimental study of the achieved improvement of the quality of GS pulses is presented. The pulses have been characterized through the evaluation of their autocorrelation traces and a study using a Temporal Information Via Intensity (TIVI) algorithm. Results show that HNOLM provides direct compression and pulse shaping for picosecond complex pulses obtained from a DFB COTS laser operating within the 1550 nm window. The experimental observations are contrasted with a theoretical modeling of the system, and an excellent agreement is observed.