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Coplanar electrode directly modulated lasers with different cavity length
Author(s) -
Xu Borui,
Sun Jiazheng,
Xia Shijun,
Zhu Sha,
Liu Yu,
Zhu Ninghua,
Sun Wenhui
Publication year - 2021
Publication title -
microwave and optical technology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 76
eISSN - 1098-2760
pISSN - 0895-2477
DOI - 10.1002/mop.32780
Subject(s) - materials science , optoelectronics , parasitic capacitance , laser , coplanar waveguide , electrode , bandwidth (computing) , capacitance , optics , linearity , oscillation (cell signaling) , electrical engineering , telecommunications , physics , computer science , engineering , chemistry , biochemistry , quantum mechanics , microwave
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‐μm, 250‐μm, and 300‐μm 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‐μm 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.