112 Gbps CMOS-compatible waveguide germanium photodetector for the 2 <bold>μ</bold>m wavelength band with a 3.64 A/W response

Yupeng Zhu; Zhi Liu; Zhipeng Liu; Yiling Hu; Qinxing Huang; Yazhou Yang; Xiangquan Liu; Tao Men; Guangze Zhang; Jun Zheng; Yuhua Zuo; Buwen Cheng

doi:10.1364/PRJ.528458

Photonics Research, Volume. 12, Issue 11, 2633(2024)

112 Gbps CMOS-compatible waveguide germanium photodetector for the 2 μm wavelength band with a 3.64 A/W response

Yupeng Zhu^1,2, Zhi Liu^1,2,3、*, Zhipeng Liu^1,2, Yiling Hu^1,2, Qinxing Huang^1,2, Yazhou Yang^1,2, Xiangquan Liu^1,2, Tao Men^1,2, Guangze Zhang^1,2, Jun Zheng^1,2, Yuhua Zuo^1,2,4、*, and Buwen Cheng^1,2

Author Affiliations

¹Key Laboratory of Optoelectronic Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China

²Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China

³e-mail: zhiliu@semi.ac.cn

⁴e-mail: yhzuo@semi.ac.cn

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Figures & Tables(9)

Fig. 1. Structure of the waveguide-integrated Ge photodetector. (a) Three-dimensional schematic and (b) cross-section view of the proposed device. (c), (d) Simulated static optical field and electric field distribution in Ge region. The simulated bias voltage is −8 V. (e) Optical microscope image of the waveguide Ge PD with an active length of 150 μm. The inset in (a) is the simulated optical reflection spectrum of the DBR.

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Fig. 2. (a) Measured I-V curves without illumination (dark) and with different input optical powers Pin. (b) Measured responsivity with different input optical powers Pin. (c) Measured multiplication gain at different bias voltages as the input power Pin varies. The inset in (b) shows the ratio of the responsivity between the proposed PD with DBR and the reference PD without DBR.

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Fig. 3. Experimental setup for (a) small-signal radio frequency (RF) measurements and (b) eye diagram measurements. The red and black lines represent the electrical and optical links, respectively. VNA, vector network analyzer; PC, polarization controller; LN MZM, lithium niobate Mach–Zehnder modulator; TDFA, thulium-doped fiber amplifier; VOA, variable optical attenuator; AWG, arbitrary waveform generator; DUT, device under test; RF Amp, RF amplifier.

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Fig. 4. (a) Equivalent circuit model for Ge PD. (b) Measured and simulated reflection coefficients for the proposed Ge PD at −4 V.

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Fig. 5. (a) Normalized optic-electro frequency response (S21) of the Ge PD at 2 μm under the bias voltages of −4 to −9 V. The drops at around 46 GHz are introduced by the response of the LN MZM. (b) 3-dB bandwidths and responsivity at 2 μm from −2 to −9 V and (c) corresponding GBP.

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Fig. 6. Review of the responsivity and 3-dB bandwidth of high-speed photodiodes operating at 2 μm wavelength reported in recent years.

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Fig. 7. (a) Measured 56 and 70 Gbps NRZ eye diagrams at 7.5, 8.0, 8.5, and 9.0 V. (b) Measured 90 and 112 Gbps PAM-4 eye diagrams at 7.5, 8.0, 8.5, and 9.0 V.

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Table 1. Extracted Electrical Parameters for the Proposed Ge PD at −4 V
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Table 1. Extracted Electrical Parameters for the Proposed Ge PD at −4 V
Parameter Value Parameter Value
$R_{s}$ 4 Ω $C_{para}$ 12 fF
$C_{j}$ 56 fF $L_{para}$ 74 pH
$R_{Si}$ 1788 Ω $R_{para}$ 0.05 Ω
$C_{ox}$ 140 fF

Table 2. Literature Overview of the State-of-the-Art High-Speed Photodetectors Operating at 2 μm Wavelength in Different Material Groups^a

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Table 2. Literature Overview of the State-of-the-Art High-Speed Photodetectors Operating at 2 μm Wavelength in Different Material Groups^a

Device Type	Absorption Material	$λ$ (μm)	$R_{esp}$ (A/W)	$I_{dark}$ (μA)	$f_{3 dB}$ (GHz)	Reception Speed (Gbps)
SI [22]	InGaAs/GaAsSb	2	0.35	0.15	3.7	–
WG [23]	InGaAs/GaAsSb	2	0.84	0.005	10	10 (NRZ)
SI [24]	InGaAs/GaAsSb	2	0.07	0.003	25	30 (NRZ)
SI [14]	GeSn	2	0.014	0.23	30	–
SI [25]	GeSn	2	0.232	44.6	1.6	–
SI [26]	GeSn	2	0.49	200	40	50 (NRZ)
WG [27]	Ge	2.02	0.3 at 30 V	1 at 30 V	1.25 at 30 V	28 (NRZ)
WG [28]	Ge	1.95	1.05 at 29 V	$\sim$ 40 at 29 V	6.12 at 29 V	16 (NRZ)
WG (this work)	Ge	2	0.78 at 7 V 2.14 at 8 V 3.64 at 9 V	14 at 7 V27 at 8 V596 at 9 V	44.7 at 7 V44.0 at 8 V39.4 at 9 V	70 (NRZ) 112 (PAM-4)

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Yupeng Zhu, Zhi Liu, Zhipeng Liu, Yiling Hu, Qinxing Huang, Yazhou Yang, Xiangquan Liu, Tao Men, Guangze Zhang, Jun Zheng, Yuhua Zuo, Buwen Cheng, "112 Gbps CMOS-compatible waveguide germanium photodetector for the 2 μm wavelength band with a 3.64 A/W response," Photonics Res. 12, 2633 (2024)

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Paper Information

Category: Silicon Photonics

Received: May. 8, 2024

Accepted: Sep. 6, 2024

Published Online: Oct. 31, 2024

The Author Email: Zhi Liu (zhiliu@semi.ac.cn), Yuhua Zuo (yhzuo@semi.ac.cn)

DOI:10.1364/PRJ.528458

Topics

laser devices and laser physics

Lasers and Laser Optics

Laser physics

laser manufacturing

Instrumentation, Measurement and Metrology

Table 1. Extracted Electrical Parameters for the Proposed Ge PD at −4 V

Table 1. Extracted Electrical Parameters for the Proposed Ge PD at −4 V

Table 2. Literature Overview of the State-of-the-Art High-Speed Photodetectors Operating at 2 μm Wavelength in Different Material Groupsa

Table 2. Literature Overview of the State-of-the-Art High-Speed Photodetectors Operating at 2 μm Wavelength in Different Material Groupsa

Table 2. Literature Overview of the State-of-the-Art High-Speed Photodetectors Operating at 2 μm Wavelength in Different Material Groups^a

Table 2. Literature Overview of the State-of-the-Art High-Speed Photodetectors Operating at 2 μm Wavelength in Different Material Groups^a