Highly linear heterogeneous-integrated Mach-Zehnder interferometer modulators on Si

Abstract

In this paper we demonstrate highly linear Mach-Zehnder interferometer modulators utilizing heterogeneous integration on a Si substrate (HS-MZM). A record high dynamic range was achieved for silicon devices, obtained using hybrid III-V/Si phase modulation sections and single drive push-pull operation, demonstrating a spurious free dynamic range (SFDR) of 112 dB∙Hz^2/3 at 10 GHz, comparable to commercial Lithium Niobate MZMs.

Ultralinear heterogeneously integrated ring-assisted Mach–Zehnder interferometer modulator on silicon

“…To cancel it with the intrinsic nonlinearity of the index change would require operation at a wavelength close to the bandgap, which increases insertion loss, causing the SFDR to suffer. The results of the heterogeneous MZI modulator have shown an overall nonlinearity similar to that of the MZI response alone [14].…”

“…The operating principle of the RAMZI modulator has been described in previous work [11,12] under the assumption that the index modulation itself is perfectly linear, as is the case with the Pockels effect in LiNbO 3 . In reality, the index modulation of the heterogeneous III-V/Si phase modulator is more complex as it involves inherently quadratic processes in the reverse biased P-I-N junction with band filling, QCSE, and, to a lesser extent, the free carrier effect [14,15]. It is important to note that both band filling and the QCSE effects are resonant phenomena and exhibit strong wavelength dependence.…”

“…To create a MZI modulator with an ultralinear transfer characteristic, the extrinsic nonlinearity of the MZI, which transforms index modulation into intensity modulation, should be balanced by the device design. When a standard heterogeneous MZI modulator is used, its extrinsic third-order nonlinearity is negative and rather large [14]. To cancel it with the intrinsic nonlinearity of the index change would require operation at a wavelength close to the bandgap, which increases insertion loss, causing the SFDR to suffer.…”

“…A silicon ring modulator with an adherently bonded LiNbO 3 thin film achieved a SFDR of 98.1 dB • Hz 2∕3 at 1 GHz and 87.6 dB • Hz 2∕3 at 10 GHz [13]. Recent work demonstrated an MZI modulator with the integration of InP-based multiple quantum wells (MQWs) [14]. The III-V layers were bonded to silicon and formed phase modulators on both arms of a silicon MZI.…”

“…The positive nonlinearity of the QCSE phase response can be sufficient to cancel the negative nonlinearities of the plasma and state-blocking effects at specific wavelength and modulator bias. The heterogeneously integrated MZI modulator achieved a high linearity, with SFDR of 112 dB • Hz 2∕3 at 10 GHz [14].…”