Y.J. Rao

University of Electronic Science and Technology of China, Hua-yang, Sichuan, China

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Publications (116)167.6 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: A graphene-coated microfiber (GCM)-based hybrid waveguide structure formed by wrapping monolayer graphene around a microfiber with length of several millimeters is pumped by a nanosecond laser at ∼1550 nm, and multi-order cascaded four-wave-mixing (FWM) is effectively generated. By optimizing both the detuning and the pump power, such a GCM device with high nonlinearity and compact size would have potential for a wide range of FWM applications, such as phase-sensitive amplification, multi-wavelength filter, all-optical regeneration and frequency conversion, and so on.
    04/2015; 3(2). DOI:10.1364/PRJ.3.000A64
  • IEEE Journal of Selected Topics in Quantum Electronics 01/2015; 21(1):1-6. DOI:10.1109/JSTQE.2014.2344050 · 3.47 Impact Factor
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    ABSTRACT: Graphene based new physics phenomena are leading to a variety of stimulating graphene-based photonic devices. In this study, the enhancement of surface evanescent field by graphene cylindrical cladding is observed, for the first time, by using a graphene-coated microfiber multi-mode interferometer (GMMI). It is found theoretically and experimentally that the light transmitting in the fiber core is efficiently dragged by the graphene, hence significantly enhancing the evanescent fields, and subsequently improving the sensitivity of the hybrid waveguide. The experimental results for gas sensing verified the theoretical prediction, and ultra-high sensitivities of ~0.1 ppm for NH<sub>3</sub> gas detection and ~0.2 ppm for H<sub>2</sub>O vapor detection are achieved, which could be used for trace analysis. The enhancement of surface evanescent field induced by graphene may pave a new way for developing novel graphene-based all-fiber devices with compactness, low cost, and temperature immunity.
    Optics Express 11/2014; 22(23):28154-62. DOI:10.1364/OE.22.028154 · 3.53 Impact Factor
  • Fei Peng, Ning Duan, Yun-Jiang Rao, Jin Li
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    ABSTRACT: It is essential to carry out real-time position and speed monitoring of trains to ensure the safety of railway operation. In this letter, the phase-sensitive optical-time-domain reflectometry ( (Phi ) -OTDR) is demonstrated to overcome the drawbacks of the track circuit, which is widely used and has the risk to be damaged by lightening, for the first time. A long sensing cable, buried nearby to two parallel railways, is used to detect the vibration signals generated by trains with (Phi ) -OTDR and the real-time vibration signals of the trains are extracted/quantified by wavelet denoising. With the edge detection by normalized sliding variance, the operation status of two nearby trains, including their relative position and speed, are obtained over a 10.2-km measurement length in real time. This letter offers a new passive way for safety monitoring of railway operation.
    IEEE Photonics Technology Letters 10/2014; 26(20):2055-2057. DOI:10.1109/LPT.2014.2346760 · 2.18 Impact Factor
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    ABSTRACT: 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.
    Optics Letters 10/2014; 39(20). DOI:10.1364/OL.39.005866 · 3.39 Impact Factor
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    ABSTRACT: In this Letter, a graphene-coated D-shaped fiber (GDF) chemical gas sensor is proposed and demonstrated. Taking advantage of both the graphene-induced evanescent field enhancement and the in-fiber multimode interferometer, the GDF shows very high sensitivity for polar gas molecule adsorptions. An extinction ratio of up to 28 dB within the free spectrum range of ∼30 nm in the transmission spectrum is achieved. The maximum sensitivities for NH<sub>3</sub> and H<sub>2</sub>O gas detections are ∼0.04 and ∼0.1 ppm, respectively. A hybrid sensing scheme with such compactness, high sensitivity, and online monitoring capabilities may pave the way for others to explore a series of graphene-based lab-on-fiber devices for biochemical sensing.
    Optics Letters 10/2014; 39(20):6030-3. DOI:10.1364/OL.39.006030 · 3.18 Impact Factor
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    ABSTRACT: Graphene Bragg gratings (GBGs) on microfiber are proposed and investigated in this paper. Numerical analysis and simulated results show that the mode distribution, transmission loss, and central wavelength of the GBG are controllable by changing the diameter of the microfiber or the refractive index of graphene. Such type of GBGs with tunability may find important applications in optical fiber communication and sensing as all-fiber in-line devices.
    Optics Express 10/2014; 22(20). DOI:10.1364/OE.22.023829 · 3.53 Impact Factor
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    ABSTRACT: An inline fiber-optic micro Fabry–Perot (MFP) cavity and a short fiber Bragg grating (SFBG) is overlapped to form an integrated MFP/SFBG sensor for simultaneous measurement of temperature and strain under high temperature (300°C). The FP cavity is fabricated on a GeO2 doped photon sensitive fiber by using the 157nm laser micro-machining technique and the SFBG is written at the same position of the MFP cavity by using the standard 248nm laser method. As the MFP cavity and the SFBG have different sensitivity coefficients to temperature and strain, they can be utilized for realization of simultaneous measurement of dual parameters.
    IEEE Photonics Technology Letters 09/2014; 26(17). DOI:10.1109/LPT.2014.2331359 · 2.18 Impact Factor
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    ABSTRACT: Random lasing (RL) characteristics through different combinations of single-mode fiber (SMF) and dispersion compensated fiber (DCF) with a Raman pump (i.e., DCF is mounted at the front or at the end of the SMF; the length of the SMF and DCF is also changeable) are studied in this paper. The results indicate that the position and length ratio of DCF and SMF influence the output of the random distributed feedback fiber laser (RDF-FL) greatly (e.g., lasing threshold, spectrum stability, and shape). When the DCF is located at a position where higher laser power is distributed, RL can be enhanced remarkably. In addition, second-order RDF-FL is realized in an SMF/DCF mixed cavity pumped bidirectionally from the fiber center, indicating that the pump method is also an important factor that influences the performance of the RDF-FL. These results are useful for revealing the role of DCF in RL and light amplification, and also for providing theoretical support for flexible design and optimization of the RDF-FL.
    Journal of the Optical Society of America B 08/2014; 31(8). DOI:10.1364/JOSAB.31.001885 · 1.81 Impact Factor
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    ABSTRACT: 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.
    Optics Letters 08/2014; 39(15). DOI:10.1364/OL.39.004313 · 3.39 Impact Factor
  • Wei Li Zhang, Fen Wang, Yun Jiang Rao, Yao Jiang
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    ABSTRACT: This paper proposes a novel concept of refractive index sensing taking advantage of 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 wavelength and reflectivity of this dip are sensitive to variation of ambient refractive index, which provides a potential way to realize refractive index sensing with a large measuring range and high sensitivity.
    Optics Express 06/2014; 22(12):14524-14529. DOI:10.1364/OE.22.014524 · 3.53 Impact Factor
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    ABSTRACT: Random lasing (RL) characteristics of second-order random fiber laser formed solo by dispersion compensated fiber are studied. It is found that the threshold of first-order RL is only 0.45 W. In addition, a special route to stable second-order lasing is revealed, i.e., a special arc-shape output spectrum of second-order RL and three chaotic regimes during evolution from the first RL to the second-order one with increased pump power.
    IEEE Photonics Technology Letters 02/2014; 26(3):246-248. DOI:10.1109/LPT.2013.2291575 · 2.18 Impact Factor
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    ABSTRACT: A method for realizing low-threshold all-optical bistable logic control is proposed based on Tamm plasmons (TPs), which are formed in an asymmetric dielectric Bragg reflector (DBR)-metal-DBR (ADMD) structure with a layer of Kerr medium embedded. The ADMD structure supports two TPs due to coupling of trapped modes at each metal-DBR interface, generating two dips in the structure's reflection spectrum. Thus, control (i.e., pump) and controlled (i.e., probe) light with wavelengths close to the two dips, respectively, can be imported. It is verified theoretically that, thanks to the enhanced Kerr nonlinearity related to excitation of high-quality TP, bistable switching at very low injection intensity can be initiated by strength or direction variation of the pump. Meanwhile, the probe changes correspondingly with the pump. Thus, all-optical bistable logic operation of the probe can be controlled by the pump.
    Optics Letters 10/2013; 38(20):4092-5. DOI:10.1364/OL.38.004092 · 3.39 Impact Factor
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    ABSTRACT: Taking advantage of relatively strong Rayleigh scattering and Raman gain of dispersion compensated fiber (DCF), three configurations to form efficient random fiber lasers (RFL) are proposed in this paper. Compared with the reported RFL formed by single-mode fiber (SMF) solely, lasing threshold and length of the proposed RFL are effectively reduced through combination of DCF and SMF. In addition, FBGs with central wavelengths at the 1st and 2nd -order Raman Stokes wavelengths are also added to the hybrid SMF/DCF cavity to further reduce the lasing threshold, leading to realization of a new kind of 2nd-order RFL.
    Optics Express 04/2013; 21(7):8544-9. DOI:10.1364/OE.21.008544 · 3.53 Impact Factor
  • Y.J. Rao, W.L. Zhang
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    ABSTRACT: This paper reviews recent progress in random fiber lasers (RFLs), including fundamental studies on their physical characteristics, design and analysis, as well as their applications, i.e., novel lasers, sensing, and amphfication indicating that RFLs would have an impact on Fiber Optics. Furthermore, the research progress in RFLs at University of Electronic Science and Technology of China (UESTC) is presented.
    Optical Communications and Networks (ICOCN), 2013 12th International Conference on; 01/2013
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    ABSTRACT: In this paper, we reported the realization of an ultra-long ring fiber laser (RFL) with hybrid emission related to both random lasing and cavity resonance. Compared with a linear random fiber laser (LRFL), the Rayleigh scattering (RS) inducting distributed feedback effect and the cavity inducting resonance effect exist simultaneously in the laser, which reduces the lasing threshold considerably and provides a hybrid way to form random lasing (RL). The laser output can be purely modeless RL when pump power is high enough. It is also discovered that the laser is insensitive to temperature variation and mechanical disturbance, this is unique and quite different from conventional RFLs which are environmentally unstable due to existence of the cavity modes.
    Optics Express 09/2012; 20(20):22563-8. DOI:10.1364/OE.20.022563 · 3.53 Impact Factor
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    ABSTRACT: We find that the random fiber laser (RFL) without point-reflectors is a temperature-insensitive distributed lasing system for the first time. Inspired by such thermal stability, we propose the novel concept of utilizing the RFL to achieve long-distance fiber-optic remote sensing, in which the RFL offers high-fidelity and long-distance transmission for the sensing signal. Two 100km fiber Bragg grating (FBG) point-sensing schemes based on RFLs are experimentally demonstrated using the first-order and the second-order random lasing, respectively, to verify the concept. Each sensing scheme can achieve >20dB optical signal-to-noise ratio (OSNR) over 100km distance. It is found that the second-order random lasing scheme has much better OSNR than that of the first-order random lasing scheme due to enhanced lasing efficiency, by incorporating a 1455nm FBG into the lasing cavity.
    Optics Express 07/2012; 20(16):17695-700. DOI:10.1364/OE.20.017695 · 3.53 Impact Factor
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    ABSTRACT: A novel distributed Raman amplification based on Random Distributed feedback fiber laser (RDFB-FL) is proposed for the first time. The experimental results confirmed its unique ultra-low intensity noise performance for the proposed distributed amplification. We also provided a new fully distributed measurement method for optical signal-to-noise (OSNR) based on stimulated Brillouin scattering for the first time.
    Opto-Electronics and Communications Conference (OECC); 07/2012
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    ABSTRACT: In this paper, we reported the realization of 2nd-order random lasing in a half-opened fiber cavity, which is formed by a FBG with central wavelength at the 1st-order Raman Stokes wavelength and a single-mode fiber (SMF) performing as a random distributed feedback mirror. Using this proposed method, the threshold of 1st-order (2nd-order) random lasing is reduced to 0.7 (2.0) W, which is nearly 2 times lower than that observed in a completely-opened cavity.
    Optics Express 06/2012; 20(13):14400-5. DOI:10.1364/OE.20.014400 · 3.53 Impact Factor
  • W. L. Zhang, Y. J. Rao
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    ABSTRACT: In a double-well microcavity, coupling of spatial polariton solitons between the two wells is studied theoretically. Polaritons trapped inside the double-well structure can demonstrate bistability where both bright and dark polariton solitons are supported. Due to the tunneling effect, the combination of polariton solitons in the two wells can be bright-bright, dark-bright or dark-dark dependent on the initial states (i.e., on-state, off-state, or mixed-state) of the polaritons. (C) 2012 Elsevier Ltd. All rights reserved.
    Chaos Solitons & Fractals 04/2012; 45(4-4):373-377. DOI:10.1016/j.chaos.2012.01.008 · 1.50 Impact Factor

Publication Stats

1k Citations
167.60 Total Impact Points

Institutions

  • 2005–2014
    • University of Electronic Science and Technology of China
      • State Key Laboratory of Electronic Thin Films and Integrated Devices
      Hua-yang, Sichuan, China
  • 2000–2011
    • Chongqing University
      • • Key Laboratory of Optoelectronic Technology and System of the Education Ministry of China
      • • School of Opto-Electronic Engineering
      Ch’ung-ch’ing-shih, Chongqing Shi, China
  • 2002
    • Aston University
      • Department of Electrical, Electronic and Power Engineering
      Birmingham, England, United Kingdom
  • 1994–1999
    • University of Kent
      • • School of Physical Sciences
      • • Applied Optics Group
      Cantorbery, England, United Kingdom
  • 1998
    • Brunel University London
      अक्सब्रिज, England, United Kingdom