Broadband and tunable optical frequency comb based on1550 nm verticalcavity surface-emitting laser under pulsed current modulation and optical injection br

Optical frequency combs (OFCs) each consist of a set of equally spaced discrete frequency components, andthey have been widely applied to many fields such as metrology, optical arbitrary waveform generation,spectroscopy, optical communication, and THz generation. In this work, we propose a scheme for generatingbroadband and tunable OFCs based on a 1550 nm vertical-cavity surface-emitting laser (VCSEL) under pulsedcurrent modulation and optical injection. Firstly, a pulsed electrical signal is utilized to drive a 1550 nm-VCSELinto the gain-switching state with a broad noisy spectrum. Next, a continuous optical wave is further introducedfor generating broadband and tunable OFC. Under injection light with power of 18.82 mu W and wavelength of1551.8570 nm, and pulsed electrical signal with a frequency of 0.5 GHz and pulse width of 200 ps, an OFC witha bandwidth of 82.5 GHz and CNR of 35 dB is experimentally acquired, and the single sideband phase noise atthe 0.5 GHz reaches -123.3 dBc/Hz at 10 kHz. Moreover, the influences of injection light wavelength, frequencyand width of pulse electrical signal on the performance of generated OFC are investigated. The experimentalresults show that OFCs with different comb spacings can be obtained by varying the frequency of pulsedelectrical signal. For the frequency of pulsed current signal varying in a range of 0.25 GHz -3 GHz, thebandwidth of generated OFCs can exceed 60 GHz through selecting optimized injection optical wavelength and width of pulse electrical signal.