Ultra-long-distance distributed fiber-optic sensing based on Brillouin optical time-domain analysis (BOTDA) is achieved by using a proposed configuration of hybrid distributed Raman amplification (H-DRA), that is realized by incorporating random fiber laser (RFL) based 2nd-order pump and low-noise laser-diode (LD) based 1st-order pump. A repeater-less sensing distance of up to 154.4km with 5m spatial resolution and ~±1.4°C temperature uncertainty is successfully demonstrated, which is the longest repeater-less BOTDA reported to date.
A novel distributed Raman amplification (DRA) scheme based on ultra-long fiber laser (UL-FL) pumping with a ring cavity rather than a linear cavity is proposed and demonstrated, for the first time. As a typical application of the proposed configuration, ultra-long-distance distributed sensing with Brillouin optical time-domain analysis (BOTDA) over 142.2km fiber with 5m spatial resolution and ± 1.5℃ temperature uncertainty is achieved, without any repeater, for the first time. The key point for the significant performance improvement is the system could offer both of uniform gain distribution and considerably suppressed pump-probe relative intensity noise (RIN) transfer, by optimized design of system structure and parameters.
The random distributed feedback fiber laser (RDFB-FL), firstly proposed and demonstrated by S. K. Turitsyn et al.,
has been designated as the significant breakthrough in the fields of laser physics and nonlinear optics. In this paper,
the fully distributed Raman amplification approach, based on the novel concept of RDFB-FL, is proposed and
presented for the first time. As a typical proof-of-concept, the high-performance distributed sensing with ±1°C
temperature accuracy and ±2m spatial resolution, over entire 122km long-range Brillouin optical time-domain
analyzer (BOTDA), has been demonstrated using the fully distributed second-order Raman amplification based on
RDFB-FL proposed. The experimental results confirmed its unique ultra-low noise performance for the proposed
distributed amplification. We believe it's the best sensing result for such a length of BOTDA so far. The underlined
physical mechanisms associated with its quasi-lossless transmission and partial coherence characteristics, are also
presented, in order to account for this much attractive feature.
The novel concept of utilizing a random fiber laser (RFL) to extend the sensing distance of fiber-optic sensing systems is
proposed for the first time to our knowledge. In this paper, two schemes based on the RFL with a fiber Bragg grating
(FBG) are experimentally demonstrated to verify the concept. The first one is a 100km FBG temperature sensing system,
in which a 100km RFL provides an effective way to enhance the sensing signal of the FBG sensor due to its strong lasing
radiation across the 100km fiber span. It is the first time to find that the RFL without the FBG is a temperatureinsensitive
distributed lasing cavity, which offers stable long-distance transmission for the sensing signal. The second
one is a 100km Brilloiun optical time domain analyzer (BOTDA), in which the generated random lasing is used as a
fully distributed Raman pump and hence stable Raman amplification can be obtained to enhance the Brilloiun sensing
signal. In principle, such a novel concept can be adopted for any type of distributed fiber-optic sensors as the RFL can be
used as a stable distributed Raman pump for sensing signal amplification along the whole length of the fiber.
The influence of the non-local effect on sensing performance in long-distance Brillouin optical time-domain analyzer
(BOTDA) based on bi-directional Raman amplification has been investigated theoretically. The results show that, the
system error induced by non-local effect worsens with increased powers of probe and Raman pump waves.
The combination of Raman amplification and optical pulse coding (OPC) is proposed to reduce the frequency
uncertainty in long-distance BOTDA under higher spatial resolution. The experimental characterization of 74.6Km
temperature sensing with measurement accuracy ~1oC under ~2.5m spatial resolution over the whole length of
sensing fiber is demonstrated. The performance comparisons of BOTDA with purely Raman amplification and
combined Raman amplification with OPC are also displayed.
The dynamic single-mode and modulation performance of λ/4 phase-shifted distributed feedback laser
diode with chirped grating (QWS-CG-DFB) are analyzed theoretically. The numerical simulation
shows that, In contrast to purely QWS-DFB laser, the enhanced dynamic single-mode suppression ratio
(SMSR) can be reached by QWS-CG-DFB laser; Under the smaller biasing current, the modulation
band-width in presence of chirped grating is narrower, this difference shrinks for larger biasing current;
For large signal modulation, the chirped grating is helpful to increase the output extinction ratio, but
worsens the frequency chirping.
All-optical wavelength conversion based on four-wave mixing (FWM) is one of the key techniques for building
dynamic optical networks. In this paper, the cavity enhancing effect of the residual F-P cavity mode on the
non-degenerated four-wave mixing (NDFWM) in a distributed-feedback semiconductor laser diode (DFB-LD) have
been investigated both experimentally and theoretically. The conversion efficiency of NDFWM is obtained at small or
large frequency detuning range. The results show that the NDFWM can be enhanced obviously when the probe
wavelength matches one of the F-P cavity modes, and the high conversion efficiency can be achieved even if the
frequency detuning between the injection probe frequency and free-running frequency of the DFB-LD is up to THz.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.