0.2 V Drive Voltage Substrate Removed Electro-Optic Mach–Zehnder Modulators With MQW Cores at 1.55 μm

Abstract

Novel electro-optic modulators in compound semiconductor epilayers using substrate removal techniques are reported. Epilayer consists of a p-i-n junction in which i layer is composed of an InGaAlAs/InAlAs MQW. This creates an optical mode with very strong vertical confinement and overlapping very well with the large electric field of the reverse biased p-i-n junction. This approach combined with the large quadratic electro-optic coefficient due to MQW improves efficiency of modulation significantly. Mach-Zehnder electro-optic modulators fabricated using this approach has 0.2 V (0.6 V) V π for 3 (1) mm long electrodes at 1.55 μm under push pull drive corresponding to record modulation efficiency of 0.06 V•cm. Index Terms-Compound semiconductor modulators, integrated optics, optical modulators. I. INTRODUCTIONO PTICAL modulator is a key component for a wide range of applications requiring electrical to optical conversion. These include fiber optic communications, RF photonics, optical signal processing and instrumentation. Electro-optic modulators are among the most commonly used modulator types. One of the key metrics for an electro-optic modulator is the drive voltage needed to switch the modulator from on to off state or vice versa. This parameter is also known as V π . Electrical power required to turn the modulator on and off is proportional to the square of this parameter. Clearly a low V π modulator is needed to reduce electrical power consumption. Electro-optic modulators are fabricated in different material platforms such as LiNbO 3 [1], [2], polymer [3] and compound semiconductors [4]. Such modulators typically have V π values of about a few volts and higher. Presently most commonly used electro-optic modulators are made in LiNbO 3 . They have low frequency V π of around 3 V with bandwidths around 20 GHz. This value increases with frequency and bandwidth. In an electro-optic modulator, there is a tradeoff between V π and bandwidth. There are reports of very wide bandwidth LiNbO 3 modulators approaching 100 GHz [1]. But these devices have V π of about 10 V. High V π values Manuscript

Low Voltage, High Optical Power Handling Capable, Bulk Compound Semiconductor Electro-Optic Modulators at 1550 nm

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Heterogeneously integrated ITO plasmonic Mach–Zehnder interferometric modulator on SOI

“…Lithium niobate-based MZIs are commercially available featuring rather high FOMs (VpL = 10 4 -10 5 V•µm) due to their field-based modulation mechanism characterized by the weak Pockels effect necessitating extremely long device lengths in the range of 1-10 centimeters. Improvements in performance are obtained with the QCSE in III-V [31,33,35] or enhanced Pockels effect in emerging materials such as polymers [28,32,[37][38][39]. Augmented light-confinement for improving optical and RF mode overlap (G) with the active material in plasmonic structures have also been sought [37][38][39] (Table 1).…”

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