Taking silicon photonics modulators to a higher performance level: state-of-the-art and a review of new technologies

Abdul Rahim; Artur Hermans; Benjamin Wohlfeil; Despoina Petousi; Bart Kuyken; Dries Van Thourhout; Roel Baets

doi:10.1117/1.AP.3.2.024003

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Advanced Photonics
Vol. 3, Issue 2, 024003 (2021)

Taking silicon photonics modulators to a higher performance level: state-of-the-art and a review of new technologies

Abdul Rahim^1、2、*, Artur Hermans^1、2, Benjamin Wohlfeil³, Despoina Petousi³, Bart Kuyken^1、2, Dries Van Thourhout^1、2, and Roel Baets^1、2、*

Author Affiliations

¹Ghent University, Photonics Research Group, Department of Information Technology, Ghent, Belgium

²Ghent University, IMEC and Center for Nano- and Biophotonics, Ghent, Belgium

³ADVA Optical Networking, Berlin, Germany

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DOI: 10.1117/1.AP.3.2.024003 Cite this Article Set citation alerts

Abdul Rahim, Artur Hermans, Benjamin Wohlfeil, Despoina Petousi, Bart Kuyken, Dries Van Thourhout, Roel Baets, "Taking silicon photonics modulators to a higher performance level: state-of-the-art and a review of new technologies," Adv. Photon. 3, 024003 (2021) Copy Citation Text

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(a) Baseline architecture of carrier injection, carrier depletion, and carrier accumulation plasma dispersion phase shifters. (b) Various configurations of plasma dispersion phase shifters.

Fig. 1. (a) Baseline architecture of carrier injection, carrier depletion, and carrier accumulation plasma dispersion phase shifters. (b) Various configurations of plasma dispersion phase shifters.

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Representative cross sections of (a) FK-based EAMs and (b) QCS effect-based EAMs in SiPh. This figure also highlights the integration route for the respective EAMs. The term monolithic refers to the integration of a material with an SOI substrate using wafer-scale epitaxial growth resulting in PICs made out of one substrate technology in mass on a wafer level.

Fig. 2. Representative cross sections of (a) FK-based EAMs and (b) QCS effect-based EAMs in SiPh. This figure also highlights the integration route for the respective EAMs. The term monolithic refers to the integration of a material with an SOI substrate using wafer-scale epitaxial growth resulting in PICs made out of one substrate technology in mass on a wafer level.

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Fig. 3. Representative cross sections of (a)

{LiNbO}_{3}

, (b) BTO, (c) PZT, and (d) organics modulators in SiPh. This figure also highlights the integration route for each material. The term monolithic refers to the integration of a material with a SiPh substrate using wafer-scale epitaxial growth resulting in PICs made out of one substrate technology in mass on a wafer level.

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Fig. 4. Representative cross sections of (a) III–V on Si phase modulator and (b) III–V on Si EAM.

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Fig. 5. Representative cross sections of (a) single-layer graphene phase/amplitude modulator and (b) double-layer graphene amplitude/phase modulator in SiPh.

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The landscape of high-speed modulators in silicon photonics
Modulation	Operating principle	Platform	Reported optical implementation	Reported driver implementation
Phase	Plasma dispersion effect by carrier	Silicon	MZI, michelson, resonators (ring, disk, ph. crystal, Fabry–Perot), slow-light structure, Bragg reflectors	Lumped, traveling wave (TW), segmented
(a) Injection
(b) Accumulation
(c) Depletion
Pockels effect	${LiNbO}_{3}$ on silicon	MZI	Lumped, TW
Organics on silicon	MZI, ring resonator	Lumped, TW
BTO on silicon	MZI, ring resonator	Lumped, TW
PZT on silicon	MZI, ring resonator	Lumped
Interband transitions	2D materials on silicon	MZI, ring resonator	Lumped, TW
Carrier accumulations/carrier depletion+Franz-Keldysh effect	III-V on silicon	MZI, ring resonator	Lumped, TW
Amplitude	Franz-Keldysh effect	Silicon-germanium	Waveguide, MZI	Lumped
Quantum confined Stark effect	Ge-Si-Ge quantum wells	Waveguide, Fabry–Perot cavity	Lumped
Electrical gating	2D materials on silicon	Waveguide	Lumped
Quantum confined Stark effect	III-V on silicon	Waveguide	Lumped

Table 1. Prominent approaches for high-speed modulation in SiPh. The modulator implementations in SiPh use a variety of physical phenomenons, materials, optical architectures, and driver architectures.

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Principle	Modulation efficiency $V_{π} \cdot L$ ( $V \cdot cm$ )	Loss (dB/cm)	Lengtha of phase shifter (mm)	Data rateb(Gb/s)	Energy/bit (fJ/bit)
Carrier injectionc	< $0.5$ (0.058⁸)	$\sim 70$ (28⁷)	$\geq 0.1$ to < $0.3$	< $40$ (70⁷)	$\sim 1000$ for MZMs and RMs (0.1f^,⁹⁸)
Carrier accumulationd	< $0.3$ (0.16⁶⁹)	50 to 80 ( $\sim 35$ ⁶⁹)	$\leq 0.5$	$\sim 40$ (40⁵)	> $200$ for MZMs, < $200$ (3¹⁰⁵) for SLMsg
Carrier depletione	$\sim 2$ (0.52⁹)	10 to 30 (2.6¹⁰)	> $1$	> $40$ (100¹²²^,¹²³)	$\sim 200$ for MZMs (32.4¹⁹), < $40$ for RMs (0.9¹⁸)

Table 2. Typical and state-of-the-art performance matrix for the plasma dispersion high-speed phase modulators. The parentheses contain the best-reported result for a performance attribute. The matrix includes the results reported for O-band and C-band demonstrations.

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Principle	FoM ER/IL	Loss (dB)	Modulator length (mm)	Data ratea (Gb/s)	Energy/bit (fJ/bit)
FK effectb	< $2$ (2³¹)	< $6$ (4.8¹³³)	$\sim 0.050$	> $40$ (100¹³⁷)	< $50$ (13²⁰)
Quantum-confined Stark effectc	< $2$ (7.9¹⁴⁹)	< $6$ (1.3¹⁴⁹)	< $0.25$	< $10$ (7¹⁴⁷)	< $100$ (16¹⁴⁸)

Table 3. Typical and state-of-the-art performance matrix for amplitude modulation by the FK effect and QCS effect. The best-reported performance attributes are mentioned in parentheses.

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Scheme	Modulation efficiency $V_{π} \cdot L$ ( $V \cdot cm$ )	Loss (dB/cm)	Length of phase shifter (mm)	Data rateb(Gb/s)	Energy/bit (fJ/bit)
${LiNbO}_{3}$ integrated with SiPhc	< $3$ (2.2¹⁷⁴)	$\sim 1$ (0.98¹⁷⁴)	> $1$	> $70$ (100¹⁷⁴)	> $100$ (170¹⁷⁴)
${BaTiO}_{3}$ integrated with SiPhd	< $0.5$ (0.2¹⁸²)	> $40$ (6¹⁸²)	> $1$	> $40$ (72¹⁸⁰)	< $100$ ¹⁷⁹
PZT integrated with SiPhe	1 (1¹⁸³)	1 (1¹⁸³)	> $2$	40 (40¹⁸⁴)	-
Organics integrated with SiPhf	< $0.05$ (0.032¹⁹⁰)	< $45$ (20²²⁸)	< $1.5$	> $50$ (100¹⁹⁶)	< $100$ (0.7¹⁹²)

Table 4. Typical and state-of-the-art performance matrix for the ferroelectric and organic high-speed phase modulators in SiPh.a The parentheses contain the best-reported result for a performance attribute.

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Operation	Modulation efficiency $V_{π} \cdot L$ ( $V \cdot cm$ )	Loss (dB/cm)	Length of phase shifter (mm)	Data ratea(Gb/s)	Energy/bit (fJ/bit)
Forward biased III–V on Si as a phase modulatord	< $0.1$ (0.047¹⁶¹)	< $30$ (19.4¹⁶¹)	< $0.5$	> $30$ (32¹⁶³^,b)	$\geq 100$
Reverse biased III–V on Si as a phase modulatord	< $0.2$ (0.11¹⁶⁴)	(28²⁸⁰)	< $0.5$	200c^,²⁸⁰	$\leq 100$ ²⁸⁰
Operation	FoM ER/IL	Loss (dB)	Modulator length (mm)	Data ratea (Gb/s)	Energy/bit (fJ/bit)
III–V on Si as an amplitude modulatord	$\sim 2$ (2¹⁴⁰)	(4.9¹⁴⁰)	$\leq 0.1$	$\sim 50$ (50)¹⁴⁰	-

Table 5. Typical and state-of-the-art performance matrix for the III–V on Si high-speed modulators in SiPh. The parentheses contain the best-reported result for a performance attribute.

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Operation	Modulation efficiency $V_{π} \cdot L$ ( $V \cdot cm$ )	Loss (dB/cm)	Length of phase shifter (mm)	Data ratea(Gb/s)	Energy/bit (fJ/bit)
2D Materials on Si as phase modulatorb	< $0.5$ (0.28²⁰¹)	> $200$ (236²⁰¹)	< $0.5$ d	$\sim 10$ (10²⁰¹)	$\sim 1000$ (600)¹) for MZM; < $500$ for RM
Operation	FoM ER/IL	Loss (dB)	Modulator Length (mm)	Data ratea (Gb/s)	Energy/bit (fJ/bit)
2D Materials on Si as amplitude modulatorc	< $3$ (4.9¹⁵⁵)	< $4$ (0.9²⁰³)	< $0.15$	> $10$ (50¹⁵⁴)	$\sim 100$ (40²⁰²)

Table 6. Typical and state-of-the-art performance matrix for graphene on Si high-speed modulators in SiPh. The parentheses contain the best-reported result for a performance attribute.