High speed silicon electro-optical modulators enhanced via slow light propagation

Abstract

While current optical communication networks efficiently carry and process huge amounts of digital information over large and medium distances, silicon photonics technology has the capacity to meet the ceaselessly increasing demand for bandwidth via energy efficient, inexpensive and mass producible short range optical interconnects. In this context, handling electrical-to-optical data conversion through compact and high speed electro-optical modulators is of paramount importance. To tackle these challenges, we combine the attractive properties of slow light propagation in a nanostructured periodic waveguide together with a high speed semiconductor pn diode, and demonstrate a highly efficient and mass manufacturable 500 µm-long silicon electro-optical device, exhibiting error free modulation up to 20 Gbit/s. These results, supported by modulation rate capabilities reaching 40 Gbit/s, pave a foreseeable way towards dense, low power and ultra fast integrated networks-on-chip for future chip-scale high performance computing systems. ©2011 Optical Society of America

Recent breakthroughs in carrier depletion based silicon optical modulators

“…The electrodes should also be designed such that the velocity of the electrical signal is matched to the velocity of the light in the waveguide. Any velocity mismatch will mean that the drive signal will not act on the same portion of [59]. RF propagation loss should be minimised.…”

“…The key in these devices is to use highly efficient phase modulators in order to produce a sufficient modulation depth with a lower drive voltage. Employing a slow light waveguide in which to produce the phase modulator is one possibility to achieve a high efficiency [59,72]. Dispersion engineering can be used to mitigate against the problem of wavelength and temperature sensitivity which these devices usually suffer from to some extent [72].…”

High-contrast 40 Gb/s operation of a 500 μm long silicon carrier-depletion slow wave modulator

“…Despite the constant endeavor toward the realization of high-performance devices, carrierdepletion modulators persistently find themselves facing parametric-adjustment trade-offs. As a result, building a modulator that simultaneously features high speed (40 Gb ∕ s), small footprint (a few hundred micrometers), low insertion loss (IL) (<6 dB), and low drive voltage (∼1 V) appears to be more challenging than initially thought [1][2][3][4][5][6]. It is now increasingly believed that the use of slow light may help mitigate these trade-offs.…”

“…It is now increasingly believed that the use of slow light may help mitigate these trade-offs. As a matter of fact, slow light was foreseen [7] and more recently shown [4,8] as providing an exciting opportunity to significantly enhance conventional "fast light" devices for numerous applications ranging from telecom and datacom to sensing via enlarged light-matter interactions. This paper aims to plainly showcase the advantages of slow light via demonstrating a highly efficient, compact, high-contrast, and low-loss silicon slow wave modulator.…”

Towards Compact and High Speed Silicon Modulators

“…Meanwhile, we demonstrated the first carrier depletion-based slow wave modulator as a means to enhance the modulation efficiency [48]. This result is the central achievement of this thesis.…”