Digital-analog hybrid optical phase-lock loop for optical quadrature phase-shift keying

Lu, Sihan; Zhou, Yu; Zhu, Funan; Sun, Jianfeng; Yan, Yang; Zhu, Rihong; Hu, Shengnan; Zhang, Xiaoxi; Zhu, Xiaolei; Hou, Xinjuan; Chen, Weibiao

doi:10.3788/col202018.090602

Cited by 11 publications

(9 citation statements)

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“…When received power is more than −19 dBm, both of the downstream and upstream BER results are lower than 10 −8 , which verifies the feasibility of the wavelength synchronization system. In subsequent experiments, the phase of the signal can be locked automatically by the optical phase-locked loop [22,23] , which will imply coherent detection, and further improves the communication quality of the system.…”

Section: Methodsmentioning

confidence: 99%

Wavelength synchronization technology for UDWDM-PON transmitter based on injection locking

et al. 2021

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We propose a concept of wavelength synchronization to ensure the stability of ultra-dense channels in an ultra-dense wavelength division multiplexing passive optical network (UDWDM-PON) transmitter. A mode-locked laser is used to provide wavelength references for users. By injection locking the semiconductor laser, the separation of the wavelength reference is realized in an optical line terminal. The downlink and uplink wavelength references are interlaced and distributed to facilitate the synchronization of uplink carriers. In the optical network unit, the uplink optical carriers are filtered by injection locking semiconductor lasers, which achieve wavelength synchronization for the uplink users. In this Letter, an adaptive wavelength synchronization transmitter for UDWDM-PON is realized with a channel spacing of 5 GHz.

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Section: Methodsmentioning

confidence: 99%

Wavelength synchronization technology for UDWDM-PON transmitter based on injection locking

et al. 2021

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“…After the two BDs are completely subtracted to eliminate the communication square term and direct current (DC) term, I and Q voltage signals are obtained as follows with

[ 37 ]

where

;

and

;

and

are I and Q noise, respectively.…”

Section: Principle and Device Of Coherent/non-coherent Ook Reception ...mentioning

confidence: 99%

Sensitivity Deterioration of Free-Space Optical Coherent/Non-Coherent OOK Modulation Receiver by Ambient Light Noise

Ren

Sun

Cong

et al. 2023

Sensors

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In free-space optical (FSO) communication systems, on–off keying (OOK) is a widely used modulation format. Coherent and non-coherent OOK receivers with sensitivities of −54.60 dBm and −51.25 dBm, respectively, were built with a communication rate of 1 Gbit/s and a bit error rate of 10−3. In an FSO communication system, the parameters must be designed to ensure a sufficient link margin. In contrast to optical fiber systems, FSO systems have ambient light (AL) noise such as sunlight. The efficiency of sunlight coupling in the single-mode fiber (SMF) of the receivers was calculated in this study. For a signal light with AL, the change in the main components of noise and the sensitivity deterioration were theoretically analyzed and experimentally verified in conditions of coherent reception and non-coherent reception with a preamplifier. For coherent reception, the theoretical sensitivity deterioration results are consistent with the experimental results which indicate that coherent reception exhibits better anti-AL noise performance than non-coherent reception when the power spectral density of the AL is the same. Coherent and non-coherent receivers coupled with SMF can work in direct sunlight. When the receiver lens diameter is greater than 4.88 × 10−4 m, the anti-AL noise performance of the receiver can be improved by increasing the receiver lens diameter.

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“…Furthermore, to obtain a long-term coherent time, the phase noise of the Raman operation laser has to be as low as possible. Plenty of technologies, such as optical phase locking (OPL) [21][22][23][24][25] and directly modulated lasers [26][27][28][29] , have been developed to generate phase-coherent optical fields with gigahertz frequency difference for Raman operation. Among these technologies, OPL typically necessitates two separate laser sources and complex electrical feedback controls and suffers from poor robustness and high system complexity.…”

Section: Introductionmentioning

confidence: 99%

Generation of visible Raman operation laser by a fiber electro-optical modulator feedback loop

Li,

Ye,

Chen

et al. 2024

中国光学快报

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Phase-coherent multi-tone lasers play a critical role in atomic, molecular, and optical physics. Among them, the Raman opeartion laser for manipulating atomic hyperfine qubits requires gigahertz bandwidth and low phase noise to retain long-term coherence. Raman operation lasers generated by directly modulated and frequency-multipled infrared lasers are compact and stable but lack feedback control to actively suppress the phase noise, which limits their performance in practical applications. In this work, we employ a fiber electro-optical modulator driven by a voltage-controlled oscillator (VCO) to modulate a monochromatic laser and employ a second-harmonic generation process to convert it to the visible domain, where the beat note of the Raman operation laser is stabilized by controlling the output frequency of VCO with a digital phase-locked loop (PLL). The low-frequency phase noise is effectively suppressed compared to the scheme without active feedback and it reaches −80 dBc=Hz@5 kHz with a 20 kHz loop bandwidth. Furthermore, this compact and robust scheme effectively reduces the system's complexity and cost, which is promising for extensive application in atomic, molecular, and optical physics.

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Digital-analog hybrid optical phase-lock loop for optical quadrature phase-shift keying

Cited by 11 publications

References 0 publications

Wavelength synchronization technology for UDWDM-PON transmitter based on injection locking

Wavelength synchronization technology for UDWDM-PON transmitter based on injection locking

Sensitivity Deterioration of Free-Space Optical Coherent/Non-Coherent OOK Modulation Receiver by Ambient Light Noise

Generation of visible Raman operation laser by a fiber electro-optical modulator feedback loop

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