Backward supercontinuum generation seeded by random distributed feedback fiber laser is proposed and demonstrated. Fully-distributed random lasing is firstly used as an effective pump laser to generate supercontinuum in the hybrid configuration with TrueWave fiber and dispersion compensated fiber. Supercontinuum in both propagating directions are generated through the collective nonlinear effects. It is found backward supercontinuum possesses much lower dynamical amplitude fluctuation in time domain. Random distributed lasing pumped supercontinuum generation not only enrich both the research scope of supercontinuum and random fiber laser, but also provide a practical way for development of stable broadband sources for OCT applications.
A novel broadband light source based on supercontinuum (SC) generation seeded by random distributed feedback fiber laser (RFL) is proposed and demonstrated for the first time. A half-opened fiber cavity formed by FBG and TrueWave fiber is used to generate random lasing and SC simultaneously. Experimental results indicate that RFL can be used as an effective pump for generation of SC. SC with 20-dB bandwidth of >250 nm was obtained. Such a broadband SC light source seeded by RFL may pave a way to generate high power broadband RFLs for use in optical sensing and measurement.
With the growing demand for monitoring length and channel number of the fully distributed optical fiber sensors (DOFSs), the amount of sensing data is increasing rapidly, and there will be a heavy pressure for the massive data storage and transmission. In this paper, two lossless compression algorithms of Lempel-Ziv-Welch (LZW) and Huffman are comparatively studied to effectively compress the huge amount of data of typical DOFSs, e.g. Φ -OTDR, POTDR, and BOTDA systems. The comparison results show that the LZW based on dictionary has a better performance in the consuming time and compression ratio for the DOFS data.
Phase-( Φ -) and Polarization- sensitive (P-) Optical-Time-Domain Reflectometries (OTDRs) are both representative optical fiber fence technologies, which have promising applications in long or ultra-long perimeter security with precise location ability. However, the challenge is that they are liable to be interfered by environmental influences due to their high sensitivity feature. Real human intrusions are always buried in the environmental noises and interferences, which lead to poor detection results. Thus it is proposed in this paper to extract human intrusion signals and separate the complicated noisy backgrounds by using a multi-scale Wavelet decomposition method. Practical test results prove its effectiveness.
An improved Brillouin-assisted photonic microwave downconverter that features simple structure and wide frequency tunable range is experimentally demonstrated. In order to obtain higher conversion efficiency, SBS-assisted notch filter is used to suppress the carrier of phase modulated signal. Due to the SBS-assisted notch-filtering is generated by the phase modulated signal itself, which simplify the system structure effectively. Furthermore, the effective suppression of the carrier of phase modulated signal and the diminishment of the second-order Stokes wave could be achieved simultaneously by optimizing the attenuation of the variable optical attenuator, which guarantee our scheme can operate over a wide frequency range.
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.
This paper proposes a novel concept of refractive index sensing based on a high-refractive-index-contrast optical Tamm plasmon (OTP) structure, i.e., an air/dielectric alternate-layered distributed Bragg reflector (DBR) coated with metal. In the reflection spectrum of the structure, a dip related to the formation of OTP appears. The dip wavelength and reflectivity are sensitive to ambient refractive index, which provides a potential way to achieve refractive index sensing with a large measurement range and high sensitivity.
Highly stable single-wavelength and broadband random fiber lasers are reported as potential light sources for use in photonic sensing, for the first time, which are based on the hybrid pumping with mixing of Er-doped fiber (EDF) and single-mode fiber (SMF).
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 novel concept of utilizing the second-order random fiber laser (RFL) to realize long-distance fiber-optic pointsensing
systems is proposed. The sensing system consists of a pump laser, a fiber Bragg grating (FBG) at the pump side
and 100km single mode fiber (SMF), and another FBG at the end of the SMF. The first FBG is used to enhance the
lasing efficiency, and the second FBG is use as the remotely-located sensing head. The Bragg wavelengths of the two
FBGs correspond to the first-order and the second-order random lasing spectrum, respectively. Its ability for remote
temperature sensing is experimentally demonstrated.
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.