Graphene based widely-tunable and singly-polarized pulse generation with random fiber lasers.

Pulse generation often requires a stabilized cavity and its corresponding mode structure for initial phase-locking. Contrastingly, modeless cavity-free random lasers provide new possibilities for high quantum efficiency lasing that could potentially be widely tunable spectrally and temporally. Pulse generation in random lasers, however, has remained elusive since the discovery of modeless gain lasing. Here we report coherent pulse generation with modeless random lasers based on the unique polarization selectivity and broadband saturable absorption of monolayer graphene. Simultaneous temporal compression of cavity-free pulses are observed with such a polarization modulation, along with a broadly-tunable pulsewidth across two orders of magnitude down to 900 ps, a broadly-tunable repetition rate across three orders of magnitude up to 3 MHz, and a singly-polarized pulse train at 41 dB extinction ratio, about an order of magnitude larger than conventional pulsed fiber lasers. Moreover, our graphene-based pulse formation also demonstrates robust pulse-to-pulse stability and wide-wavelength operation due to the cavity-less feature. Such a graphene-based architecture not only provides a tunable pulsed random laser for fiber-optic sensing, speckle-free imaging, and laser-material processing, but also a new way for the non-random CW fiber lasers to generate widely tunable and singly-polarized pulses.

Long-range and high-precision correlation optical time-domain reflectometry utilizing an all-fiber chaotic source.

We propose a long range, high precision optical time domain reflectometry (OTDR) based on an all-fiber supercontinuum source. The source simply consists of a CW pump laser with moderate power and a section of fiber, which has a zero dispersion wavelength near the laser's central wavelength. Spectrum and time domain properties of the source are investigated, showing that the source has great capability in nonlinear optics, such as correlation OTDR due to its ultra-wide-band chaotic behavior, and mm-scale spatial resolution is demonstrated. Then we analyze the key factors limiting the operational range of such an OTDR, e. g., integral Rayleigh backscattering and the fiber loss, which degrades the optical signal to noise ratio at the receiver side, and then the guideline for counter-act such signal fading is discussed. Finally, we experimentally demonstrate a correlation OTDR with 100km sensing range and 8.2cm spatial resolution (1.2 million resolved points), as a verification of theoretical analysis.

Ultra-long phase-sensitive OTDR with hybrid distributed amplification.

A phase-sensitive optical time-domain reflectometry (Φ-OTDR) with 175 km sensing range and 25 m spatial resolution is demonstrated, using the combination of co-pumping second-order Raman amplification based on random fiber lasing, counter-pumping first-order Raman amplification, and counter-pumping Brillouin amplification. With elaborate arrangements, each pumping scheme is responsible for the signal amplification in one particular segment of all three. To the best of our knowledge, this is the first time that distributed vibration sensing is realized over such a long distance without inserting repeaters. The novel hybrid amplification scheme in this work can also be incorporated in other fiber-optic sensing systems for extension of sensing distance.

Phase-sensitive optical time-domain reflectometry with Brillouin amplification.

We propose a phase-sensitive optical time-domain reflectometry (Φ-OTDR) scheme with counterpumping fiber Brillouin amplification (FBA). High-sensitivity perturbation detection over 100 km is experimentally demonstrated as an example. FBA significantly enhances the probe pulse signal, especially at the second half of the sensing fiber, with only 6.4 dBm pump power. It is confirmed that its amplification efficiency is much higher than 28.0 dBm counterpumping fiber Raman amplification. The FBA Φ-OTDR scheme demonstrated in this work can also be incorporated into other distributed fiber-optic sensing systems for extension of sensing distance or enhancement of sensing signal level.

Biochip analysis of prostate cancer.

Microarray expression analysis was used to forecast the roles of differentially co-expressed genes (DCG) and DCG and links in the pathogenesis of prostate cancer. In addition, we demonstrate that the relationship between transcriptional factors (TFs) and their targets can be considered a key factor in determining the difference between primary and metastatic prostate cancer. Regulatory impact factors were adopted to calculate the impact of TF. We identified 5 TFs and 29 target genes important in the transition between normal prostate and primary prostate cancer and 2 TFs and 7 target genes important in the transition between primary and metastatic prostate cancer. These results suggest that it may be possible to predict the clinical behavior of prostate cancer based on gene expression analysis.

Screening of feature genes of the renal cell carcinoma with DNA microarray.

AIM: To investigate the underlying molecular mechanisms of renal cell carcinoma (RCC) by using the microarray expression profiles of normal kidney and RCC tissue for early diagnosis and treatment of RCC. MATERIALS AND METHODS: The gene expression profile of GES781 was downloaded from Gene Expression Omnibus database, including including nine tissue samples of RCC tissues removed from nine patients and eight adjacent normal renal tissue samples. We identified the differentially expressed genes (DEGs) by Multtest package in R software. The screened DEGs were further analyzed by bioinformatics methods. Firstly, the comparison of the DEGs expression degree was performed by cluster analysis. Secondly, DAVID was used to perform functional analysis of up- and down- regulated genes and the protein-protein interaction (PPI) networks were constructed by prePPI. Finally, the pathways of genes in PPI networks were discovered by WebGestalt. RESULTS: Compared with the control, we screened 648 down-regulated and 681 up-regulated DEGs. And the down- and up-regulated DEGs with maximum expression degree were UMOD (uromodulin) and FABP7 (fatty acid binding protein 7), respectively. There was significant difference in the gene expression between the normal kidney and RCC tissue. The up-regulated DEGs in RCC tissue were significantly related to the immune responses and the down-regulated DEGs were significantly related to the oxidation reduction. The most significant pathway in the PPI network of UMOD was cytokine-cytokine receptor interaction. CONCLUSIONS: The screened DEGs have the potential to become candidate target molecules to monitor, diagnose and treat the RCC, and might be beneficial for the early diagnosis and medication control of RCC.