A novel method to produce swept laser source using wavelengths parallel swept optical loop

In this paper, wavelengths parallel swept technique is proposed by using an optical swept loop outside the laser cavity. A frequency shifter controlled by RF signal in the loop shifts the frequencies of the incident optical signals simultaneously with a constant value in every circulation. Experimentally, the outputs of two distributed feed back (DFB) lasers were parallel swept by using the optical swept loop. The swept step is tunable from 300MHz(24pm) to 15GHz(0.12nm) depending on the electro-optical bandwidth of the frequency shifter used in our experiments. Dual-wavelength swept output at 214 kHz swept rate with 0.08nm swept step and 122 kHz swept rate with 0.04nm swept step were achieved respectively. The swept span of the swept source was 1.6nm with a flatness of ±1.5dB.