The cost and power consumption of optical transmitters are now hampering further increases in total transmission capacity within and between data centers. Photonic integrated circuits (PICs) based on silicon (Si) photonics with wavelength-division multiplexing (WDM) technologies are promising solutions. However, due to the inefficient light emission characteristics of Si, incorporating III-V compound semiconductor lasers into PICs via a heterogeneous integration scheme is desirable. In addition, optimizing the bandgap of the III-V material used for each laser in a WDM transmitter becomes important because of recent strict requirements for optical transmitters in terms of data speed and operating temperature. Given these circumstances, applying a direct-bonding scheme is very difficult because it requires multiple bonding steps to bond different-bandgap III-V materials that are individually grown on different wafers. Here, to achieve wideband WDM operation with a single wafer, we employ a selective area growth technique that allows us to control the bandgap of multi-quantum wells (MQWs) on a thin InP layer directly bonded to silicon (InP-on-insulator). The InP-on-insulator platform allows for epitaxial growth without the fundamental difficulties associated with lattice mismatch or antiphase boundaries. High crystal quality is achieved by keeping the total III-V layer thickness less than the critical thickness (430 nm) and compensating for the thermally induced strain in the MQWs. By carrying out one selective MQW growth, we successfully fabricated an eight-channel directly modulated membrane laser array with lasing wavelengths ranging from 1272.3 to 1310.5 nm. The fabricated lasers were directly modulated at 56-Gbit/s with pulse amplitude modulation with four-amplitude-level signal. This heterogeneous integration approach paves the way to establishing III-V/Si WDM-PICs for future data-center networks.

中文翻译：

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在SiO ₂ / Si上直接键合InP上进行选择性区域生长的多波长膜激光器阵列

现在，光发射器的成本和功耗阻碍了数据中心内部和数据中心之间的总传输容量的进一步增加。基于硅（Si）光子并采用波分复用（WDM）技术的光子集成电路（PIC）是有前途的解决方案。但是，由于Si的发光特性低下，因此希望通过异质集成方案将III-V族化合物半导体激光器结合到PIC中。此外，由于最近在数据速度和工作温度方面对光发射器的严格要求，因此优化WDM发射器中用于每个激光器的III-V材料的带隙变得很重要。鉴于这些情况，应用直接键合方案非常困难，因为它需要多个键合步骤来键合分别在不同晶圆上生长的不同带隙的III-V材料。在这里，为了用单个晶片实现宽带WDM操作，我们采用了选择性区域生长技术，该技术可以控制直接键合到硅上的InP薄层（绝缘体上InP）上的多量子阱（MQW）的带隙。 。绝缘体上的InP平台允许外延生长，而没有与晶格失配或反相边界相关的基本困难。通过将III-V层的总厚度保持在小于临界厚度（430 nm）的水平，并补偿MQW中的热应变，可以实现较高的晶体质量。通过选择性地进行MQW增长，我们成功地制造了八通道直接调制膜激光器阵列，其激光波长范围为1272.3至1310.5 nm。所制造的激光器以具有四个振幅电平信号的脉冲振幅调制直接以56 Gbit / s的速度调制。这种异构集成方法为将来的数据中心网络建立III-V / Si WDM-PIC铺平了道路。