Figure 6 Intensity modulation response of 600A and 750A. Note that the reverse bias voltages are 0.5 and 0 V, respectively. PF-6463922 Note that although the DC extinction ratio of 600A (750A) was reduced to less than 70% (30%) of its original modulation ability, RF measurement on the devices was still possible due to lower propagation loss after annealing. The 3-dB bandwidth of both 600A and

750A is approximately 1.6 GHz. Noting that these are preliminary RF Wortmannin nmr results, similar frequency responses of approximately 1.6 GHz for both 600A and 750A might be due to the non-optimized WG structures and RF matching. That is, the obtained RF performance was limited by the device design and not by the QD materials. Therefore, we believe that an improvement in the high-speed performance will be expected following the optimization of QD waveguide design and improved RF matching. The realization

of RF measurement on the processed (annealed) lumped-element QD-EAM confirms the prospect of QD epiwafer in monolithic integration for future references. By applying low-cost intermixing, such integration will have low insertion loss and polarization-independent properties [14]. This is because the integrated devices would actually be made from the find more same epilayers unlike other types of integration. Therefore, the EAMs would naturally be tuned to the same polarization as that of the emitted radiation from the corresponding QD lasers, and improved extinction ratio may even be observed due to the improved absorption strength of the same platform that integrated devices share. Conclusions In this work, we investigated the effects of annealing on the static and dynamic performances of lumped-element QD-EAM operating at the wavelength of 1.3 μm. The extinction ratio at −8 V (propagation loss) for the as-grown, 600°C, and 750°C DUTs was found to be 10 dB (4.0 dB/cm), 7 dB (3.7 dB/cm), and <3 dB (3.0 dB/cm), respectively. Hence, both the extinction ratio and the insertion loss decrease upon

Tyrosine-protein kinase BLK increase in annealing temperature. Most significantly, the 3-dB response of the 750°C-annealed lumped-element QD-EAM was found to be 1.6 GHz at zero reverse bias voltage. This suggests a cost- and design-effective solution to enhance transmission and will be beneficial for researchers working on the implementation of QD-EAMs in monolithic integration through the intermixing process method. Acknowledgement This work was supported in part by the DSTA Defense Innovative Research Project (POD0613635). References 1. Chu Y, Thompson MG, Penty RV, White IH, Kovsh AR: 1.3 μm quantum-dot electro-absorption modulator. In CLEO’07: Conference on Lasers and Electro-Optics: May 6–11 2007; Baltimore. Piscataway: IEEE; 2007:1–2. 2. Ngo CY, Yoon SF, Loke WK, Cao Q, Lim DR, Wong V, Sim YK, Chua SJ: Investigation of semiconductor quantum dots for waveguide electroabsorption modulator. Nanoscale Res Lett 2008, 3:486–490.CrossRef 3.