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InGaAlAs RW-based electro-absorption-modulated DFB-lasers for high-speed applications

: Moehrle, M.; Klein, H.; Bornholdt, C.; Przyrembel, G.; Sigmund, A.; Molzow, W.-D.; Troppenz, U.; Bach, H.-G.


Panajotov, K. ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Semiconductor lasers and laser dynamics VI : 14 - 17 April 2014, Brussels, Belgium
Bellingham, WA: SPIE, 2014 (Proceedings of SPIE 9134)
ISBN: 978-1-62841-082-2
Paper 913419, 9 pp.
Conference "Semiconductor Lasers and Laser Dynamics" <6, 2014, Brussels>
Conference Paper
Fraunhofer HHI ()

Electro-absorption modulated 10G and 25G DFB lasers (EML) are key components in transmission systems for long reach (up to 10 km) and extended reach (up to 80 km) applications. The next generation Ethernet will most likely be 400 Gb/s which will require components with even higher bandwidth. Commercially available EMLs are regarded as high-cost components due to their separate epitaxial butt-coupling growth process to separately optimize the DFB laser and the electro-absorption modulator (EAM). Alternatively the selective area growth (SAG) technique is used to achieve different MQW bandgaps in the DFB and EAM section of an EML. However for a lot of applications an emission wavelength within a narrow wavelength window is required enforcing a temperature controlled operation. All these applications can be covered with the developed EML devices that use a single InGaAlAs MQW waveguide for both the DFB and the EAM enabling a low-cost fabrication process similar to a conventional DFB laser diode. It will be shown that such devices can be used for 25Gb/s and 40Gb/s applications with excellent performance. By an additional monolithic integration of an impedance matching circuit the module fabrication costs can be reduced but also the modulation bandwidth of the devices can be further enhanced. Up to 70Gb/s modulation with excellent eye openings can be achieved. This novel approach opens the possibility for 100Gb/s NRZ EMLs and thus 4x100Gb/s NRZ EML-based transmitters in future. Also even higher bitrates seem feasible using more complex modulation formats such as e.g. DMT and PAM.