Author(s): Xu, BR (Xu, Borui); Sun, JZ (Sun, Jiazheng); Xia, SJ (Xia, Shijun); Zhu, S (Zhu, Sha); Liu, Y (Liu, Yu); Zhu, NH (Zhu, Ninghua); Sun, WH (Sun, Wenhui)

Source: MICROWAVE AND OPTICAL TECHNOLOGY LETTERS DOI: 10.1002/mop.32780 Early Access Date: JAN 2021

Abstract: A ridge-waveguide (RW) directly modulated laser (DML) with a coplanar electrode structure is proposed and measured in this paper. Since utilizing the coplanar electrode can significantly reduce parasitic capacitance, the frequency responses of DMLs exhibit a quite low roll-off. Shortening the cavity length L is attractive to enhance the high-speed performance of DMLs, but it will increase the mirror loss and the chip resistance at the same time. We analyzed the static and dynamic characteristics of 200-mu m, 250-mu m, and 300-mu m lasers experimentally and theoretically to investigate the impact of L on the coplanar-electrode DML. Shortening the cavity length can improve the relaxation oscillation frequency f(r) effectively. The 200-mu m DML achieves a bandwidth of 15.3 GHz. The f(r) is the most important limiting factor for the laser to obtain a wide bandwidth. Decreasing L and increasing the differential gain are promising for the further improvement of f(r). However, shortening L causes a more severe thermal effect and the deterioration of the linearity. This trade-off must be considered in the future study.

Accession Number: WOS:000610884600001

ISSN: 0895-2477

eISSN: 1098-2760

Full Text: https://onlinelibrary.wiley.com/doi/10.1002/mop.32780