Kyushu University · Engineering
Professor Guo-Wei Lu's research lab specializes in advanced optical communication technologies, with a focus on high-speed, high-spectral-efficiency optical transmission systems. The lab explores all-optical signal processing techniques such as wavelength conversion, format conversion, and phase manipulation using nonlinear fiber and semiconductor devices. Key research directions include the development of robust photonic components for extreme environments, ultra-high-speed modulation formats (e.g., 16-QAM, DQPSK, and 320-Gb/s RZ-DQPSK), and energy-efficient optical networking solutions for future datacenters. The lab also investigates novel schemes for optical multicast and signal regeneration to enhance network scalability and performance.
Figures are computed from collected data and may differ slightly.
To reduce the ever-increasing energy consumption in datacenters, one of the effective approaches is to increase the ambient temperature, thus lowering the energy consumed in the cooling systems. However, this entails more stringent requirements for the reliability and durability of the optoelectronic components. Herein, we fabricate and demonstrate silicon-polymer hybrid modulators which support ultra-fast single-lane data rates up to 200 gigabits per second, and meanwhile feature excellent reli
All-optical wavelength conversion (AOWC) plays an important role in the future transparent optical networks, in order to enhance the re-configurability and non-blocking capacity. On the other hand, high-order quadrature amplitude modulations (QAMs) have been extensively studied for achieving the high-speed and high-spectral-efficiency optical transmission. Since high-order QAMs are more sensitive to phase and amplitude noise, to implement an AOWC sub-system suitable for high-order QAM signals wi
An optical format conversion scheme of multilevel phase-shift keying (M-ary PSK) signals using the four-wave mixing based optical phase erasure is discussed in this paper. The conversion from differential quadrature phase-shift keying (DQPSK) to differential phase shift keying at 10 and 160 Gbaud, and the conversion from differential eight-ary phase-shift keying to DQPSK at 40 Gbaud have been experimentally demonstrated. The proposed scheme could be used as a phase erasure, in which a redundant
We propose a novel 16-quadrature amplitude modulation (QAM) transmitter based on two cascaded IQ modulators driven by four separate binary electrical signals. The proposed 16-QAM transmitter features scalable configuration and stable performance with simple bias-control. Generation of 16-QAM signals at 40 Gbaud is experimentally demonstrated for the first time and visualized with a high speed constellation analyzer. The proposed modulator is also compared to two other schemes. We investigate the
Through four-wave mixing (FWM) process in highly-nonlinear fiber (HNLF) or semiconductor device, the phase-modulation depth of one converted FWM component could be doubled compared with that of the original input signal. Therefore, with a multilevel phase-modulated signal and a CW light as inputs, after FWM process in a nonlinear media, phase pattern (0, pi) carried in the input multilevel phase-modulated signal will not be transferred to one converted FWM component, which could be referred to a
In this paper, we discuss the multicast efficiency issue in the optical layer multicast. A 1-to-8 phase-preserved different phase-shifted keying (DPSK) wavelength multicast is experimentally demonstrated using four-wave mixing (FWM) in a piece of Bismuth highly nonlinear fiber (Bi- HNLF). DPSK signal is successfully delivered from one wavelength to up to eight different wavelengths using only three pumps. Compared with the existing schemes, the multicast efficiency is greatly improved by deliver
We propose an all-optical phase-interleaving technology based on dual-pump four-wave mixing (FWM) in highly nonlinear fiber (HNLF). The proposed all-optical phase-interleaving technology is applied in an all-optical phase-multiplexing scheme to successfully phase-multiplex 2times or 3 times 10-Gb/s DPSK-WDM signals to a 20- or 30-Gb/s DPSK in non-return-to-zero (NRZ) formats. The proposed all-optical phase multiplexing scheme is demonstrated using dual-pump FWM in highly nonlinear silica and bis
In order to adapt to the dynamics in the future optical networks, we propose a flexible high-order QAM transmitter using a tandem in-phase/quadrature (IQ) modulators to synthesize different high-order quadrature amplitude modulation (QAM) formats, such as 16QAM, 32 or 36QAM and 64QAM. To generate high-order QAMs, an offset-QAM is firstly generated using an IQ modulator driven by electronics with reduced modulation-level, and then mapped to other quadrants through another following IQ modulator c
We experimentally demonstrated ultra-fast phase-transparent wavelength conversion using cascaded sum- and difference-frequency generation (cSFG-DFG) in linear-chirped periodically poled lithium niobate (PPLN). Error-free wavelength conversion of a 160-Gb/s return-to-zero differential phase-shift keying (RZ-DPSK) signal was successfully achieved. Thanks to the enhanced conversion bandwidth in the PPLN with linear-chirped periods, no optical equalizer was required to compensate the spectrum distor
In this letter, we propose and experimentally demonstrate an enhanced radio-frequency (RF) spectrum analysis technique to simultaneously monitor optical signal-to-noise ratio (OSNR) and polarization-mode dispersion (PMD) for return-to-zero ON- OFF keying (RZ-OOK) systems. In this method, by cascading a large differential group delay element at the monitoring module, the PMD and OSNR parameters can be derived from the analysis of the position shift and the minimum power of the RF spectral dip, re
Optical wavelength conversion (OWC) is expected to be a desirable function in future optical transparent networks. Since high-order quadrature amplitude modulation (QAM) is more sensitive to the phase noise, in the OWC of high-order QAM signals, it is crucial to suppress the extra noise introduced in the OWC subsystem, especially for the scenario with multiple cascaded OWCs. Here, we propose and experimentally demonstrate a pump-linewidth-tolerant OWC scheme suitable for high-order QAM signals u
We propose and experimentally investigate a novel WDM-PON architecture using inverse-RZ modulated centralized light sources. The finite optical power in each bit of the downstream IRZ signal can greatly facilitate the upstream data re-modulation.
We propose and experimentally demonstrate an all-optical phase multiplexing scheme using four-wave mixing in a highly nonlinear fiber. Two 10-Gb/s pi/2-shifted return-to-zero (RZ) differential phase-shift-keying (DPSK) wavelength-division-multiplexing (WDM) signals are successfully phase-multiplexed into a 20-Gb/s RZ differential quadrature phase-shift-keying signal with a negative 1.6-dB power penalty. With more input DPSK WDM signals, the proposed scheme can be applied to obtain a multilevel p
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Optical logic gate, especially exclusive-or (XOR) gate, plays important role in accomplishing photonic computing and various network functionalities in future optical networks. On the other hand, optical multicast is another indispensable functionality to efficiently deliver information in optical networks. In this paper, for the first time, we propose and experimentally demonstrate a flexible optical three-input XOR gate scheme for multiple input phase-modulated signals with a 1-to-2 multicast
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