Abstract

Based on the pre-emphasis 4-level pulse amplitude modulation (PAM-4) format at a symbol rate of 32 GBaud, the comparisons among optical PAM-4 data transmissions through back-to-back (BtB), 100-m OM4 multi-mode fiber (MMF), and 100-m OM5-MMF links are discussed in detail by employing the directly modulated few-transverse-mode (FM) vertical cavity surface emitting laser (VCSEL) chip at 850 nm as the carrier. The bare FM-VCSEL chip exhibits an oxide-confined aperture of 5 μm to provide 3–4 transverse modes with low threshold current (I_th) of 0.25 mA and high optical power of 1.2 mW at a bias current of 38 I_th. The impendence of 65 Ω and the 3-dB bandwidth of 24 GHz are obtained by setting the DC point of the FM-VCSEL at 6.25 mA. With the bias current optimization and the pre-emphasis, the receiving bit error ratio (BER) of the 32-GBaud PAM-4 data meets the KP4-forward error correction criterion of 2.4 × 10⁻⁴, which enables the FM-VCSEL successfully achieving the 64-Gbit/s data stream transmission through the BtB and 100-m OM4-/OM5-MMF links. As compared to the BtB transmission with a BER of 2.5 × 10⁻⁸, replacing OM4 with OM5 for the 64-Gbit/s PAM-4 transmission reduces the receiving power penalty from 3.41 to 0.86 dB and improves the BER from 3.8 × 10⁻⁵ to 3.8 × 10⁻⁶. That is mainly attributed to the higher effective modal bandwidth and compensated modal and chromatic dispersions of the OM5-MMF as compared to the OM4-MMF when delivering the FM-VCSEL carried PAM-4 data stream.

Single-mode VCSEL for pre-emphasis PAM-4 transmission up to 64  Gbit/s over 100–300  m in OM4 MMF

Hsuan-Yun Kao, Cheng-Ting Tsai, Shan-Fong Leong, Chun-Yen Peng, Yu-Chieh Chi, Huai-Yung Wang, Hao-Chung Kuo, Chao-Hsin Wu, Wood-Hi Cheng, and Gong-Ru Lin
Photon. Res. 6(7) 666-673 (2018)

Coupling angle tolerance of the 850-nm single-mode VCSEL output collimated by lensed OM4-MMF or GI-SMF for a NRZ-OOK link

Shao-Yung Lee, Chih-Hsien Cheng, Kun-You Huang, Xin Chen, Kangmei Li, Chia-Hsuan Wang, Ming-Jun Li, Chao-Hsin Wu, and Gong-Ru Lin
Opt. Express 30(10) 17130-17139 (2022)

Comparison of single-/few-/multi-mode 850 nm VCSELs for optical OFDM transmission

Hsuan-Yun Kao, Cheng-Ting Tsai, Shan-Fong Leong, Chun-Yen Peng, Yu-Chieh Chi, Jian Jang Huang, Hao-Chung Kuo, Tien-Tsorng Shih, Jau-Ji Jou, Wood-Hi Cheng, Chao-Hsin Wu, and Gong-Ru Lin
Opt. Express 25(14) 16347-16363 (2017)

Nearly 70  Gbit/s NRZ-OOK encoding of a dual-mode 850  nm VCSEL with a highly In-doped and small Zn-diffused emission area

Gong-Ru Lin, Chih-Hsien Cheng, Hao-Chung Kuo, Shao-Yung Lee, Xin Chen, Chia-Hsuan Wang, Ming-Jun Li, Yu-Ming Huang, Wei-Ta Huang, and Dong Yang
Photon. Res. 10(7) 1602-1616 (2022)

Few-mode VCSEL chip for 100-Gb/s transmission over 100  m multimode fiber

Hsuan-Yun Kao, Yu-Chieh Chi, Cheng-Ting Tsai, Shan-Fong Leong, Chun-Yen Peng, Huai-Yung Wang, Jian Jang Huang, Jau-Ji Jou, Tien-Tsorng Shih, Hao-Chung Kuo, Wood-Hi Cheng, Chao-Hsin Wu, and Gong-Ru Lin
Photon. Res. 5(5) 507-515 (2017)