Browsing by Author "Wang, Huai-Yung"

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4-Gbit/s visible light communication link based on 16-QAM OFDM transmission over remote phosphor-film converted white light by using blue laser diode
(2015-12-28)
Retamal, Jose Ramon Duran
;
Oubei, Hassan Makine
;
Janjua, Bilal
;
Chi, Yu-Chieh
;
Wang, Huai-Yung
Visible Light Communication (VLC) as a new technology for ultrahigh-speed communication is still limited when using slow modulation light-emitting diode (LED). Alternatively, we present a 4-Gbit/s VLC system using coherent blue-laser diode (LD) via 16-quadrature amplitude modulation orthogonal frequency division multiplexing. By changing the composition and the optical-configuration of a remote phosphor-film the generated white light is tuned from cool day to neutral, and the bit error rate is optimized from 1.9 x 10(-2) to 2.8 x 10(-5) in a blue filter-free link due to enhanced blue light transmission in forward direction. Briefly, blue-LD is an alternative to LED for generating white light and boosting the data rate of VLC. (C) 2015 Optical Society of America
4-Gbit/s visible light communication link based on 16-QAM OFDM transmission over remote phosphor-film converted white light by using blue laser diode
(2015-12-28)
Retamal, Jose Ramon Duran
;
Oubei, Hassan Makine
;
Janjua, Bilal
;
Chi, Yu-Chieh
;
Wang, Huai-Yung
Visible Light Communication (VLC) as a new technology for ultrahigh-speed communication is still limited when using slow modulation light-emitting diode (LED). Alternatively, we present a 4-Gbit/s VLC system using coherent blue-laser diode (LD) via 16-quadrature amplitude modulation orthogonal frequency division multiplexing. By changing the composition and the optical-configuration of a remote phosphor-film the generated white light is tuned from cool day to neutral, and the bit error rate is optimized from 1.9 x 10(-2) to 2.8 x 10(-5) in a blue filter-free link due to enhanced blue light transmission in forward direction. Briefly, blue-LD is an alternative to LED for generating white light and boosting the data rate of VLC. (C) 2015 Optical Society of America
4.8 Gbit/s 16-QAM-OFDM transmission based on compact 450-nm laser for underwater wireless optical communication
(2015-09-07)
Oubei, Hassan M.
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Duran, Jose R.
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Janjua, Bilal
;
Wang, Huai-Yung
;
Tsai, Cheng-Ting
We experimentally demonstrate an underwater wireless optical communications (UWOC) employing 450-nm TO-9 packaged and fiber-pigtailed laser diode (LD) directly encoded with an orthogonal frequency division multiplexed quadrature amplitude modulation (QAM-OFDM) data. A record data rate of up to 4.8 Gbit/s over 5.4-m transmission distance is achieved. By encoding the full 1.2-GHz bandwidth of the 450-nm LD with a 16-QAM-OFDM data, an error vector magnitude (EVM) of 16.5%, a signal-to-noise ratio (SNR) of 15.63 dB and a bit error rate (BER) of 2.6 x 10-3, well pass the forward error correction (FEC) criterion, were obtained. (C) 2015 Optical Society of America
850/940-nm VCSEL for optical communication and 3D sensing
(2018-01-01)
Cheng, Chih-Hsien
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Shen, Chih-Chiang
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Kao, Hsuan-Yun
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Hsieh, Dan-Hua
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Wang, Huai-Yung
This paper is going to review the state-of-the-art of the high-speed 850/940-nm vertical cavity surface emitting laser (VCSEL), discussing the structural design, mode control and the related data transmission performance. InGaAs/AlGaAs multiple quantum well (MQW) was used to increase the differential gain and photon density in VCSEL. The multiple oxide layers and oxide-confined aperture were well designed in VCSEL to decrease the parasitic capacitance and generate single mode (SM) VCSEL. The maximal modulation bandwidth of 30 GHz was achieved with well-designed VCSEL structure. At the end of the paper, other applications of the near-infrared VCSELs are discussed.
Blue Laser Diode Based Free-space Optical Data Transmission elevated to 18 Gbps over 16 m
(2017-09-05)
Huang, Yu-Fang
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Chi, Yu-Chieh
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Kao, Hsuan-Yun
;
Tsai, Chen-Ting
;
Wang, Huai-Yung
Up to 18-Gbps direct encoding of blue laser diode (BLD) is demonstrated for free-space data transmission. By reshaping the orthogonal frequency multiplexed (16-QAM OFDM) stream with sidelobe filtering, the raw data rate expedites from 17.2 to 18.4 Gbps. Employing an ultrafast p-i-n photodiode with smaller active area diameter and lower noise equivalent power significantly enlarges the data rate by 1.6 Gbps or upgrades the signal-to-noise ratio (SNR) by 0.2 dB. Replacing the 80-mW BLD with the 120-mW one essentially increases the received SNR by 0.4 dB under enhanced modulation throughput. Reinforcing the beam collimation and collection by increasing the numerical aperture with a plano-convex hyper-hemispherical lens further improves the SNR by 0.6 dB. After optimization, the 16-QAM OFDM data with and without sidelobe filtering are respectively delivered at raw data rates of 16.4 and 18 Gbps with spectral-density usage efficiency as high as 4 bit/s/Hz over 16 m in free space, wherein the BLD carried QAM-OFDM data stream remains its capacity after reformation with sidelobe filtering as the superior inter-carrier-interference immunity reinforces.
CdSe/ZnS core-shell quantum dot assisted color conversion of violet laser diode for white lighting communication
(2019-12-01)
Wang, Wei-Chun
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Wang, Huai-Yung
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Chen, Tzu-Yu
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Tsai, Cheng-Ting
;
Cheng, Chih-Hsien
By color-converting the violet laser diode (VLD) with a cadmium selenide and zinc sulfide (CdSe/ZnS) core-shell-quantum dot (QD) doped polydimethylsiloxane (PDMS) film, the VLD+CdSe/ZnS core-shell-QD transferred white-light with improved color rendering index (CRI) is demonstrated for high-speed indoor visible lighting communication. To facilitate hue saturation value (HSV) of the VLD +CdSe/ZnS core-shell-QD white-lighting module, dual-sized CdSe/ZnS core-shell-QDs with two luminescent wavelengths centered at 515 and 630 nm are doped into the PDMS. The CdSe/ZnS core-shell-QD doped PDMS phosphor with the optimized thickness of 2.5 mm serves as the beam divergent color-converter, which not only excites red (R) and green (G) fluorescence to detune the correlated color temperature (CCT) and CRI of the mixed red/green/violet (RGV) white-light, but also remains the residual VLD signal for data transmission. With a divergent angle of 127 degrees, such a VLD + CdSe/ZnS core-shell-QD can deliver cold white-light with a CCT of 6389 K and a CRI of 63.3 at Commission International de l'Eclairage coordinate of 0.3214, 0.2755. Most important, the residual VLD light component is relatively weak with its wavelength out of the peak optical sensitivity region of the human retina centered at 441 nm. The directly encoded VLD+CdSe/ZnS core-shell-QD white light successfully carries the 16-quadrature amplitude modulation (QAM) discrete multitone data, which supports the maximal transmission data rate of 9.6 Gbit/s with a bit error ratio (BER) of 3.59 x 10(-3).
Few-mode VCSEL chip for 100-Gb/s transmission over 100 m multimode fiber
(2017-10-01)
Kao, Hsuan-Yun
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Chi, Yu-Chieh
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Tsai, Cheng-Ting
;
Leong, Shan-Fong
;
Peng, Chun-Yen
A few-mode (FM) vertical cavity surface emitting laser (VCSEL) chip with heavily zinc-diffused contact layer and oxide-confined cross-section is demonstrated for carrying pre-leveled 16-quadrature amplitude modulation orthogonal frequency division multiplexing (QAM-OFDM) data in OM4 multi-mode fiber (MMF) over 100 m for intra-data-center applications. The FM VCSEL chip, which has an oxide-confined emission aperture of 5 mu m, demonstrates high external quantum efficiency, provides an optical power of 2.2 mW at 38 times threshold condition, and exhibits 3 dB direct-modulation bandwidth beyond 22 GHz at a cost of slight heat accumulation. At a DC bias point of 5 mA (22.6I(th)) the FM VCSEL chip, with sufficiently normalized modulation output, supports Baud and data rates of 25 and 100 Gb/s, respectively, with forward error correction (FEC) certifying receiving quality after back-to-back transmission. After passing through 100 m OM4 MMF with a receiving power penalty of 4 dB, the FM VCSEL chip demonstrates FEC-certified transmission of the pre-leveled 16-QAM OFDM data at 92 Gb/s. (C) 2017 Chinese Laser Press
Going beyond 4 Gbps data rate by employing RGB laser diodes for visible light communication
(2015-07-13)
Janjua, Bilal
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Oubei, Hassan M.
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Retamal, Jose R. Duran
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Ng, Tien Khee
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Tsai, Cheng-Ting
With increasing interest in visible light communication, the laser diode (LD) provides an attractive alternative, with higher efficiency, shorter linewidth and larger bandwidth for high-speed visible light communication (VLC). Previously, more than 3 Gbps data rate was demonstrated using LED. By using LDs and spectral-efficient orthogonal frequency division multiplexing encoding scheme, significantly higher data rates has been achieved in this work. Using 16-QAM modulation scheme, in conjunction with red, blue and green LDs, data rates of 4.4 Gbps, 4 Gbps and 4 Gbps, with the corresponding BER/SNR/EVM of 3.3 x 10(-3)/15.3/17.9, 1.4 x 10-3/16.3/15.4 and 2.8 x 10(-3)/15.5/16.7 were obtained over transmission distance of similar to 20 cm. We also simultaneously demonstrated white light emission using red, blue and green LDs, after passing through a commercially available diffuser element. Our work highlighted that a tradeoff exists in operating the blue LDs at optimum bias condition while maintaining good color temperature. The best results were obtained when encoding red LDs which gave both the strongest received signal amplitude and white light with CCT value of 5835K. (C) 2015 Optical Society of America
High-Temperature Insensitivity of 50-Gb/s 16-QAM-DMT Transmission by Using the Temperature-Compensated Vertical-Cavity Surface-Emitting Lasers
(2018-08-15)
Peng, Chun-Yen
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Tsai, Cheng-Ting
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Wang, Huai-Yung
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Wu, Yun-Chen
;
Shih, Tien-Tsorng
In this study, a 50-Gb/s 16-quadrature amplitude modulation discrete multitone (16-QAM-DMT) was applied to an 850-nm oxide-confined vertical-cavity surface-emitting laser (VCSEL) at various temperature ranging from 25 degrees C to 85 degrees C. This study reports the highest bit rate for directly modulated VCSELs operating at 85 degrees C, in addition to demonstrating, for the first time, 16-QAM-DMT with less dependence on slope efficiency (SE) reduction. By using a temperature-compensated VCSEL, this study determined the degradation of the bit error rate (BER) in terms of the signal-to-noise ratio. The analysis results demonstrate that the transmission quality is dominated by optical bandwidth rather than the SE. Therefore, the preleveling technique was applied for error rate recovery to reduce the BER from 6.3 x 10(-3) to 3.8 X 10(-3) with a 0.2-dB/GHz preleveling slope. Thus, a low-bandwidth system (nearly 10 GHz) was realized for high data-rate transmissions (50 Gb/s) at 85 degrees C. The 16-QAM-DMT transmission provides an effective approach to alleviating thermal problems that occur in high-speed optical communication without the requirement of any external amplification circuits.
Long-Term Thermal Stability of Single-Mode VCSEL Under 96-Gbit/s OFDM Transmission
(2019-11-01)
Kao, Hsuan-Yun
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Tsai, Cheng-Ting
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Chi, Yu-Chieh
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Peng, Chun-Yen
;
Leong, Shan-Fong
Thermal-dependent transmission performance and long-term stability of a single-transverse-mode (SM) vertical-cavity surface-emitting laser (VCSEL) with directly pre-leveled 16quadrature amplitude modulation orthogonal frequency-division multiplexing (16-QAM OFDM) data over 100 m 0M4 multi-mode-fiber (MMF) are demonstrated. Although narrowing the oxide-confined aperture to 3 mu m enables the SM VCSEL with low threshold current of 0.21 mA and high modulation bandwidth of 21.4 GHz, this technology also enlarges the insulating oxide area to accumulate the heat for raising core temperature. This induces a harsh environment as the core temperature persistently increases without dissipation even under the water-cooling control at 20 degrees C. As a result, the SM VCSEL can only guarantee a stable operation for 1.5 h under the encoding of QAM-OFDM data for transmission. After optimization, the SM VCSEL successfully supports a back-to-back transmission capacity as high as 96 Gbit/s. With the assistance of OFDM pre-leveling technique, the 96-Gbit/s QAM-OFDM data transmission is qualified over 100 m OM4 MMF with a receiving power penalty as low as 13 dB.
Nonstoichiometric SiC Bus/Ring Waveguide Based All-Optical Data Format Follower and Inverter
(2016-05)
Su, Sheng-Pin
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Wu, Chung-Lun
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Cheng, Chih-Hsien
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Huang, Bo-Ji
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Wang, Huai-Yung
Nonstoichiometric silicon carbide (SiC) bus/ring waveguide resonator based all-optical data-format follower and inverter is demonstrated to perform ultrafast dual functional wavelength and data-format conversion. The buried Si quantum dots (Si-Qps) with strong quantum confinement effect effectively result in a significant change on the nonlinear refractive index of 3.14 X 10(-1)3 cm(2)/W, which induces a red shift of 0.07 nm on the resonant wavelength comb of the nonstoichiometric SiC ring waveguide resonator. By injecting the 12 Gbit/s optical pulsed return-to-zero on-off keying (PRZ-OOK) data stream into the ring waveguide at a notched wavelength of 1551.08 nm, the induced red-shift on resonant wavelengths allows versatile all-optical data processing functions, including data wavelength conversion and data format following/inversion, on the data patterns transferred to the probe. The eye-opening diagram analysis at 12 Gbit/s reveals that the data transferred to the probe can provide a signal-to-noise ratio of 9.4 dB, and a receiving power penalty is degraded by 2.6 dB as compared to that of the pump data.
Single-mode VCSEL for pre-emphasis PAM-4 transmission up to 64 Gbit/s over 100-300 m in OM4 MMF
(2018-07-01)
Kao, Hsuan-Yun
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Tsai, Cheng-Ting
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Leong, Shan-Fong
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Peng, Chun-Yen
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Chi, Yu-Chieh
A 850 nm single-mode vertical cavity surface emitting laser (VCSEL)-based data transmission is demonstrated, enabling four-level pulse amplitude modulation (PAM-4) at 64 Gbit/s over 100-300 m in an OM4 multi-mode fiber (MMF). By optimizing the bias of the single-mode VCSEL with a differential resistance of 159 Omega, the related electrical return loss of -5.7 dB is determined to provide an analog modulation bandwidth of 18.9 GHz. After pre-emphasizing the waveform of the PAM-4 format, the PAM-4 data stream can be successfully delivered by the single-mode VCSEL at 64 Gbit/s under back-to-back and 100 m long OM4 MMF conditions. Lengthening the transmission distance worsens the signal-to-noise ratio (SNR) of PAM-4 data to the FEC criterion, as the waveform pre-emphasis of the PAM-4 data stream inevitably induces spectral power compensation from low to high frequencies. Therefore, increasing the OM4 MMF distance from 200 to 300 m significantly reduces the peak-to-peak amplitude of data to suppress the SNR and reduce the transmission capacity from 52 to 48 Gbit/s. (C) 2018 Chinese Laser Press
VCSEL with bi-layer oxidized aperture enables 140-Gbit/s OFDM Transmission over 100-m-long OM5 MMF
(2019-01-01)
Wu, Wei-Li
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Huang, Cheng-Yi
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Wang, Huai-Yung
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Lin, Yu-Hong
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Wu, Cheng-Han
A few-mode 850-nm VCSEL chip directly modulated by 16-QAM OFDM data at 140 Gbit/s is demonstrated to enable error-free transmission over 100-m-long OM5 MMF with 3.1-dB power penalty compared to the back-to-back case.
Wireless optical transmission of 450 nm, 3.2 Gbit/s 16-QAM-OFDM signals over 6.6 m underwater channel
(2016)
Oubei, Hassan M.
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Duran, Jose R.
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Janjua, Bilal
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Wang, Huai-Yung
;
Tsai, Cheng-Ting
We experimentally realized a gigabit underwater wireless optical communication system using commercially available 450 nm blue laser diode. By implementing 16-QAM-OFDM modulation, we achieved data rate of 3.2 Gbit/s with a BER of 6.83x10(-4) over 6.6 m channel.