On Power Consumption of Silicon-Microring-Based Optical Modulators

• Published in: Journal of lightwave technology Vol. 28; no. 11; pp. 1615 - 1623
• Main Authors: Ye, Tong, Cai, Xinran
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.06.2010; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applied sciences; Chirp modulation; Circuit properties; Consumption; Coupling circuits; Driving; Electric potential; Electric, optical and optoelectronic circuits; Electronics; Electrooptic modulators; Energy consumption; Exact sciences and technology; Frequency; Fundamental areas of phenomenology (including applications); Integrated optics. Optical fibers and wave guides; Integrated optoelectronics. Optoelectronic circuits; Joining; Laser optical systems: design and operation; Microring resonator; Modulation; Modulators; Optical and optoelectronic circuits; Optical coupling; Optical modulation; optical modulator; Optical resonators; Optics; Photonics; Physics; Power consumption; Resonators, cavities, amplifiers, arrays, and rings; Silicon; silicon photonics; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Transmission and modulation (techniques and equipments); Voltage; Static characteristic; Performance evaluation; Integrated optics; Microring resonator; Driving voltage; Chirp; High density; Optical modulator; Integrated circuit design; Electrooptical modulator; Coupled mode theory; Low frequency; power consumption; Push pull connection; Ring resonator; Electric power consumption; Open market; Optical modulation; silicon photonics; Comparative study
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2010.2047841

Silicon microring resonator has been recognized as a competitive structure for the electro-optic modulator due to its potential for high-density integration. There are two silicon-ring-based modulation methods: push-pull coupling modulation and index modulation. Previous investigations show that the push-pull coupling modulation seems to outperform the index modulation because of its ultralarge optical modulation bandwidth and chirp-free property. However, there is no performance comparison for these two schemes in power consumption, which has emerged as an important parameter for photonics integrated circuit design. This paper thus studies the power efficiency of these two methods. The analysis of the static characteristics of the ring shows that the index modulation requires a much lower driving voltage than that of the push-pull coupling modulation when the modulator is operated at low frequencies. The dynamic analysis based on the coupled-mode theory in time indicates that the required driving voltage of the push-pull coupling modulation is still higher than that of the index modulation when the modulation frequency is not very high. To solve this problem, we propose a chirp-free two-ring modulator consisting of a push-pull coupling modulator embedded into a ring with the same resonance. We demonstrate that the two-ring modulator can reach its transmission null before the push-pull coupling modulator becomes critical coupled. As a result, the power requirement of the two-ring modulator is lower than that of the push-pull coupling modulator.