Kaneshige Hiroki, Gautam Rajdeep, Ueyama Yuta, Katouf Redouane, Arakawa Taro, Kokubun Yasuo
Graduate School of Engineering, Yokohama National University, Yokohama, Kanagawa 240-8501, Japan.
Opt Express. 2013 Jul 15;21(14):16888-900. doi: 10.1364/OE.21.016888.
Modulation characteristics of a novel InGaAs/InAlAs multiple quantum well (MQW) microring-enhanced Mach-Zehnder modulator (MRE-MZM) is investigated in detail and its low-voltage operation with high extinction ratio is demonstrated. The MZM has a single microring resonator in one arm and is driven by the change in electrorefractive index induced by the quantum-confined Stark effect in the MQW core layer. As the MQW, a multiple five-layer asymmetric coupled quantum well (FACQW) is used to obtain a large electrorefractive index change. The driving voltage of the proposed MZM is significantly reduced owing to the enhanced phase shift in the microring resonator. High-mesa waveguide structures are grown by solid-source molecular beam epitaxy and fabricated by inductively coupled plasma etching. A directional coupler with an asymmetric branching ratio is used as an input coupler to prevent the degradation of the extinction ratio of the MZM. The extinction ratio of the fabricated MRE-MZM is approximately 27 dB. The product of the half-wave voltage and phase shifter length, V(π) · L, is 1.7 Vmm in static modulation. This value is one-quarter that of a conventional MZM with the same waveguide structure.
详细研究了一种新型InGaAs/InAlAs多量子阱（MQW）微环增强马赫曾德尔调制器（MRE-MZM）的调制特性，并展示了其具有高消光比的低电压操作。该MZM在一个臂中有一个单微环谐振器，并由MQW核心层中量子限制斯塔克效应引起的电光折射率变化驱动。作为MQW，使用多层五层非对称耦合量子阱（FACQW）来获得大的电光折射率变化。由于微环谐振器中的相移增强，所提出的MZM的驱动电压显著降低。高台面波导结构通过固态源分子束外延生长，并通过电感耦合等离子体蚀刻制造。具有非对称分支比的定向耦合器用作输入耦合器，以防止MZM的消光比降低。所制造的MRE-MZM的消光比约为27 dB。在静态调制中，半波电压与移相器长度的乘积V(π)·L为1.7 V·mm。该值是具有相同波导结构的传统MZM的四分之一。
