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Journal Article
Directly modulated lasers with graded-κ grating for stable single-mode operation and bandwidth enhancement
- Authors
- Younghoon Kim, Seok-Jun Yun, Young-Tak Han, Sang-Ho Park, Shinmo An, Young Ahn Leem, Hongsik Park, Honghwi Park, Dong-Hoon Lee
- Issue Date
- 2026-04
- Citation
- Optics Express, v.34, no.8, pp.14465-14474
- ISSN
- 1094-4087
- Publisher
- Optica Publishing Group (formerly OSA)
- Language
- English
- Type
- Journal Article
- Abstract
- We present a graded-κ grating technique that enables stable single-mode lasing and robust modulation-bandwidth enhancement in directly modulated lasers. Internal reflection at the interface between the active and passive regions typically degrades detuned-loading and photon–photon resonance effects, which limit high-speed operation. The proposed graded-κ structure suppresses these reflections by smoothing the photon-density and refractive-index transition, resulting in fluctuation-free bandwidth scaling and reliable activation of single-cavity etalon effects. The device achieves a 3-dB bandwidth of 47.5 GHz and supports 112-Gbps PAM4 transmission with TDECQ values lower than 2.9 dB up to 45 ℃, demonstrating its suitability for next-generation optical interconnect solutions in datacenters.
- KSP Keywords
- 3-dB bandwidth, 5 GHz, Active and passive, Bandwidth enhancement, Bandwidth scaling, Directly modulated laser(DML), Etalon effects, High-speed operation, Next-generation, Optical Interconnects, Passive regions