Optoelectronics Letters, Volume. 15, Issue 2, 139(2019)
VCSEL-based Raman technology for extended reachtime and reference frequency transfer systems
This paper experimentally demonstrates a low-cost energy efficient alternative technique for long reach transfer of ac-curate reference frequency (RF) clock signals for extended reach RF distribution systems. This is achieved by adoptingdistributed forward Raman amplification and vertical cavity surface emitting laser (VCSEL) technology. A class 10GVCSEL is directly modulated with a 2 GHz RF clock signal. By exploiting a forward Raman pump with the flat gainof 8.6 dB, a 100.8-km-long standard single mode fiber (SMF) RF clock distribution is experimentally achieved. Amaximum phase noise of .117.66 dBc/Hz at offset frequency of 100 kHz and an RF clock jitter (RMS) of 5.36 ps isexperimentally measured for 100.8-km-long fiber transmission without forward Raman amplification. However, withthe adoption of forward Raman amplification, the measured phase noise and RMS improves to .86.59 dBc/Hz and1.7 ps, respectively. Forward Raman pumping offers distributed high flat gain over a wide spectra range (over 35.5 nm), while VCSELs offer cost effective broadband signal distribution, therefore keeping the network optics in-vestment low.
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G. M. Isoe, E. K. Rotich, T. B. Gibbon. VCSEL-based Raman technology for extended reachtime and reference frequency transfer systems[J]. Optoelectronics Letters, 2019, 15(2): 139
Received: Jul. 4, 2018
Accepted: Jul. 30, 2018
Published Online: Apr. 16, 2019
The Author Email: Isoe G. M. (George.Isoe@nmmu.ac.za)