The stable long-distance transmission of radio-frequency(RF)signals holds significant importance from various aspects,including the comparison of optical frequency standards,remote monitoring and control,scientific re...The stable long-distance transmission of radio-frequency(RF)signals holds significant importance from various aspects,including the comparison of optical frequency standards,remote monitoring and control,scientific research and experiments,and RF spectrum management.We demonstrate a scheme where an ultrastable frequency signal was transmitted over a 50 km coiled fiber.The optical RF signal is generated using a two-section distributed feedback(DFB)laser for direct modulation based on the reconstruction equivalent chirp(REC)technique.The 3-dB modulation bandwidth of the two-section DFB laser is 18 GHz and the residual phase noise of-122.87 dBc/Hz is achieved at 10-Hz offset frequency.We report a short-term stability of 1.62×10^(-14)at an average time of 1 s and a long-term stability of 6.55×10^(-18)at the measurement time of 62,000 s when applying current to the front section of the DFB laser.By applying power to both sections,the stability of the system improves to 4.42×10^(-18)within a testing period of 56,737 s.Despite applying temperature variations to the transmission link,long-term stability of 8.63×10^(-18)at 23.9 h can still be achieved.展开更多
In this Letter,we proposed and experimentally demonstrated a directly modulated tunable laser based on the multi-wavelength distributed feedback(DFB)laser array.The lasers are placed in series to avoid the usage of an...In this Letter,we proposed and experimentally demonstrated a directly modulated tunable laser based on the multi-wavelength distributed feedback(DFB)laser array.The lasers are placed in series to avoid the usage of an optical combiner and additional power loss.A three-section design is utilized to reduce the interference from other lasers and improve the electro-optic response bandwidth.Besides,the reconstruction-equivalent-chirp technique is used to simplify the grating fabrication and precisely control the grating phase.We realized 12 channels with 100 GHz spacing with high side mode suppression ratios of above 50 dB.The output power of all the channels is above 14 mW.The 3 dB electro-optic bandwidth is above 20 GHz at a bias current of 100 mA for all four lasers.A 25 Gb/s data transmission over a standard single-mode fiber of up to 10 km is demonstrated for all 12 channels,and 50 Gb/s data per wavelength is obtained through the four-level pulse amplitude modulation.The proposed directly modulated tunable in-series DFB laser array shows the potential for a compact and low-cost light source for wavelength division multiplexing(WDM)systems,such as next-generation front-haul networks and passive optical networks.展开更多
基金supported by the National Key R&D Program of China(No.2020YFB2205804)the National Natural Science Foundation of China(Nos.62273355,61975075,61975076,and 62004094)+1 种基金the Natural Science Foundation of Jiangsu Province of China(No.BK20200334)the Jiangsu Science and Technology Project(No.BE2017003-2)。
文摘The stable long-distance transmission of radio-frequency(RF)signals holds significant importance from various aspects,including the comparison of optical frequency standards,remote monitoring and control,scientific research and experiments,and RF spectrum management.We demonstrate a scheme where an ultrastable frequency signal was transmitted over a 50 km coiled fiber.The optical RF signal is generated using a two-section distributed feedback(DFB)laser for direct modulation based on the reconstruction equivalent chirp(REC)technique.The 3-dB modulation bandwidth of the two-section DFB laser is 18 GHz and the residual phase noise of-122.87 dBc/Hz is achieved at 10-Hz offset frequency.We report a short-term stability of 1.62×10^(-14)at an average time of 1 s and a long-term stability of 6.55×10^(-18)at the measurement time of 62,000 s when applying current to the front section of the DFB laser.By applying power to both sections,the stability of the system improves to 4.42×10^(-18)within a testing period of 56,737 s.Despite applying temperature variations to the transmission link,long-term stability of 8.63×10^(-18)at 23.9 h can still be achieved.
基金supported in part by the Chinese National Key Basic Research Special Fund(Nos.2017YFA0206401,2018YFA0704402,2018YFE0201200,and 2018YFB2201801)National Natural Science Foundation of China(Nos.62004094 and 61975075)+2 种基金Natural Science Foundation of Jiangsu Province of China(No.BK20200334)Jiangsu Science and Technology Project(Nos.BE2019101 and BE2017003-2)Suzhou Technological Innovation of Key Industries(No.SYG201844).
文摘In this Letter,we proposed and experimentally demonstrated a directly modulated tunable laser based on the multi-wavelength distributed feedback(DFB)laser array.The lasers are placed in series to avoid the usage of an optical combiner and additional power loss.A three-section design is utilized to reduce the interference from other lasers and improve the electro-optic response bandwidth.Besides,the reconstruction-equivalent-chirp technique is used to simplify the grating fabrication and precisely control the grating phase.We realized 12 channels with 100 GHz spacing with high side mode suppression ratios of above 50 dB.The output power of all the channels is above 14 mW.The 3 dB electro-optic bandwidth is above 20 GHz at a bias current of 100 mA for all four lasers.A 25 Gb/s data transmission over a standard single-mode fiber of up to 10 km is demonstrated for all 12 channels,and 50 Gb/s data per wavelength is obtained through the four-level pulse amplitude modulation.The proposed directly modulated tunable in-series DFB laser array shows the potential for a compact and low-cost light source for wavelength division multiplexing(WDM)systems,such as next-generation front-haul networks and passive optical networks.
