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ABSTRACT: A fiber-optic interferometric probe based on a two-mode fiber (TMF) is proposed and demonstrated for measuring the thermo-optic coefficients (TOCs) of liquid samples. The proposed probe can be simply fabricated by fusion-splicing a short piece of TMF to a lead single mode fiber (SMF) with small lateral offset, which makes interference between LP<sub>01</sub> and LP<sub>02</sub> modes. The sensing responses of the probe to temperature and surrounding refractive index (SRI) have been experimentally investigated to show the capability of simultaneous measurements; the phase change of the reflection spectrum was related to temperature variation and the intensity change was to SRI variation. The data analysis is made not only in the spectral domain but in the Fourier domain also to effectively quantify the measurements. The TOCs of several liquid samples including water, ethanol, and acetone have been obtained with the proposed method.
Optics Express 10/2012; 20(21):23744-54. · 3.59 Impact Factor
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ABSTRACT: In this paper, we evaluate the design and performance of an entirely passive extended 10-gigabit-capable PON (XG-PON) using eight channels of coarse wavelength-division multiplexing (CWDM) in upstream transmission, which is called the Cu-XG-PON, with a first demonstration of the upstream physical layer specification for the extended class in ITU-T G.987 series of recommendations. In the new scheme, a single burst-mode receiver (BMRx) within an optical line terminal (OLT) receives arbitrary upstream data from the optical network terminals (ONTs) divided into eight groups, each group sharing a CWDM wavelength, through a CWDM filter and a power splitter as cascaded remote nodes (RNs) for the upstream link bridge. The downstream link is designed such that a high power OLT transmitter compensates for link loss using two power splitters as cascaded RNs. Based on the proposed architecture, we first analyze the overall system performance in the upstream and downstream links, and then evaluate the practical extension capabilities in terms of fiber distance and split ratio by conducting experiments to probe the upstream performance using a developed BMRx. We demonstrate that the BMRx is capable to -34.5 dBm sensitivity, which is feasible for a 36 dB optical path loss and a 0.5 dB optical path penalty with a 2 dBm ONT transmitter power. Based on the numerical analysis and experimental results, we confirm that the proposed Cu-XG-PON is capable of reaching 28 km for 256 ONTs, or 42 km for 64 ONTs, and furthermore, for ONT groups at long wavelength channels, maximum 40 km for 256 ONTs, or 60 km for 64 ONTs.
Journal of Lightwave Technology 06/2012; 30(11):1677-1684. · 2.78 Impact Factor
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ABSTRACT: We propose and demonstrate a fiber Bragg grating (FBG) sensor network employing the code division multiple access (CDMA) technique to identify information from individual sensors. To detect information without considering time delays between sensors, a sliding correlation method is applied, in which two different signals with the same pseudo-random binary sequence (PRBS) pattern, but slightly different frequencies, are applied to the source and detector sides. Moreover, for time domain detection, a wavelength-to-time conversion technique using a wavelength dispersive medium is introduced. The experimental results show that the proposed sensor network has a wide strain dynamic range of 2,400 με and a low crosstalk of 950:1.
Sensors 01/2012; 12(5):5888-95. · 1.74 Impact Factor
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IEEE Communications Letters. 01/2012; 16:98-100.
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ABSTRACT: We propose the in-band optical signal-to-noise-ratio (OSNR) monitoring method using a Mach-Zehnder interferometer. This interferometer is implemented by inserting a piece of Yb<sup>3+</sup>-doped optical fiber (YDF) between two strands of thermally expanded core (TEC) fibers: the former to give optical phase delay to one of the two arms (core and cladding modes of the YDF) and the latter to give two arm paths. By using TEC fibers to split the input signal and combine again, the fringe pattern necessary for OSNR monitoring shows polarization independence and wideband characteristics. The phase of the optical signal propagating along the core mode of YDF is changed by flowing a laser light of 976 nm to the core of YDF. Compared with the OSNR measured by optical spectrum analyzer (OSA), the errors are less than 0.5 dB over the OSNR range of 20 dB. Also, the dynamic range showed over 20 dB at the wavelength range of 1541-1566 nm.
IEEE Photonics Technology Letters 11/2011; · 2.19 Impact Factor
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ABSTRACT: We propose a new all-optical wavelength conversion technique based on cross gain modulation (XGM) in gain clamped reflective semiconductor optical amplifier (GC-RSOA). The proposed technique uses the seed light reflected from the FBG as probe signal, thereby avoiding the need of an external seed source for wavelength conversion.
ICT Convergence (ICTC), 2011 International Conference on, Seoul, South Korea; 09/2011
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ABSTRACT: We propose and experimentally demonstrate a hybrid WDM/OCDMA ring with a dynamic add/drop function based on Fourier code for local area networks. Dynamic function is implemented by mechanically tuning the Fourier encoder/decoder for optical code division multiple access (OCDMA) encoding/decoding. Wavelength division multiplexing (WDM) is utilized for node assignment and 4-chip Fourier code recovers the matched signal from the codes. For an optical source well adapted to WDM channels and its short optical pulse generation, reflective semiconductor optical amplifiers (RSOAs) are used with a fiber Bragg grating (FBG) and gain-switched. To demonstrate we experimentally investigated a two-node hybrid WDM/OCDMA ring with a 4-chip Fourier encoder/decoder fabricated by cascading four FBGs with the bit error rate (BER) of <10(-9) for the node span of 10.64 km at 1.25 Gb/s.
Optics Express 03/2011; 19(7):6243-52. · 3.59 Impact Factor
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ABSTRACT: We propose a multiplexed fiber Bragg grating sensor network based on code division multiple access (CDMA) using a self-injection locked reflective semiconductor optical amplifier. The proposed system shows improved scanning time without requiring a tunable laser source or a Fabry-Perot filter. CDMA was used to separate each reflected sensor signal and it shows a high dynamic range of over 40°C and a crosstalk ratio of 27.7:1. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 378–381, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24913
Microwave and Optical Technology Letters 12/2009; 52(2):378 - 381. · 0.62 Impact Factor
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ABSTRACT: We propose a tunable photonic microwave notch filter using a multi-wavelength optical source. Two peak wavelengths are generated using a reflective semiconductor optical amplifier (RSOA) self-injection, locked by two external fiber Bragg gratings (FBGs). The time delay required for the notch filter is obtained based on the wavelength-dependent propagation velocity through the fiber. The tunable filter characteristic is obtained by changing the center wavelength of one of the gratings and its tunability is limited only by the gain profile of the RSOA and the tuning range of the grating. Based on the proposed structure, a two-tap microwave notch filter with free spectral range tunable from 1.15 to 5.79 GHz is experimentally demonstrated. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 134–138, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24841
Microwave and Optical Technology Letters 11/2009; 52(1):134 - 138. · 0.62 Impact Factor
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ABSTRACT: A robust Raman fibre laser (RFL) for tunable and multiple outputs has been proposed using an all-fibre asymmetric cavity which is composed of a wideband chirped fibre Bragg grating (CFBG) and narrowband tunable fibre Bragg gratings (TFBGs). The wideband CFBG has high reflectivity across the spectral range from 1404 to 1465 nm as an input reflector. Output couplers (OCs) consist of three TFBGs with center wavelengths of 1410, 1425 and 1440 nm, respectively, which can each be tuned over 10 nm. The output power and wavelength can be flexibly controlled by tuning of TFBGs in the 14xx nm band.
Measurement Science and Technology 02/2009; 20(3):034022. · 1.49 Impact Factor
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ABSTRACT: We propose and experimentally demonstrate a surveillance technique based on spectral analysis of self-injection locked reflective semiconductor optical amplifier (SL-RSOA) for in-service monitoring of power splitter - passive optical networks (PS-PON). The proposed technique analyzes the cavity mode frequency of upstream transmitter at the optical network unit (ONU) to distinguish each branch fiber from other fiber branches of PS-PON without utilizing any additional surveillance source at the central office (CO).
PhotonicsGlobal@Singapore, 2008. IPGC 2008. IEEE; 01/2009
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ABSTRACT: An optical signal-to-noise ratio (OSNR) monitoring technique using a cascaded long-period fiber grating with a tunable phase shifter is proposed for non return-to-zero on-off-keying (NRZ-OOK) and differential phase shift keying (DPSK) signals. This method is based on two key points: first, the cascaded long period fiber grating (CLPG) acts as an optical delay interferometer (ODI) by Mach-Zehnder configuration consisting of the core and cladding modes inside the CLPG. Secondly, an optically tunable phase shifter using an Yb(3+) doped optical fiber (YDF) is inserted between the CLPG. The phase of the modulated signal propagating along the core mode of YDF is controlled by adjusting pumping power of 976-nm laser diode (LD). By combining the CLPG with the optically tunable phase shifter, the OSNR monitoring could be successfully executed.
Optics Express 01/2009; 16(25):20603-9. · 3.59 Impact Factor
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ABSTRACT: OSNR monitoring technique from 10-Gb/s NRZ-OOK and DPSK signal using a cascaded long-period fiber grating with a tunable phase shifter demonstrated. The monitoring error is within 0.5 ps, and this scheme is not affected by the PMD.
Optical Fiber Communication & Optoelectronic Exposition & Conference, 2008. AOE 2008. Asia; 12/2008
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ABSTRACT: We demonstrate a TOTDR based on direct modulation of self-injection locked RSOA for line monitoring of WDM-PON. The proposed TOTDR has 30 nm tuning range and 50 m resolution.
Optical Communication, 2008. ECOC 2008. 34th European Conference on; 10/2008
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ABSTRACT: We propose a tunable optical time-domain reflectometer (OTDR) for in-service monitoring of wavelength- division- multiplexing passive optical networks (WDM-PONs). The proposed method uses a reflective semiconductor optical amplifier, which is self-injection-locked by a tunable fiber Bragg grating. The proposed tunable OTDR has a tuning range of 30 nm and a resolution of 50 m. The performance of the proposed scheme is experimentally evaluated to demonstrate the in-service monitoring of WDM-PON.
IEEE Photonics Technology Letters 09/2008; · 2.19 Impact Factor
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ABSTRACT: Colorless upstream transmission is demonstrated using a self-injection locked RSOA for a range of 24 nm, achieving error free performance after upstream transmission at 1.25-Gb/s over 20-km SMF. The receiver sensitivities were of < -28.5 dBm.
Opto-Electronics and Communications Conference, 2008 and the 2008 Australian Conference on Optical Fibre Technology. OECC/ACOFT 2008. Joint conference of the; 08/2008
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ABSTRACT: We propose a serialized sensor network using a reflected SOA (RSOA) as a low-cost and wideband source. The RSOA is self-injection locked by the FBG sensors with different center wavelengths. By reading the wavelength shifts, the number of sensors up to 32 can be monitored with the side mode suppression ratio of ≫27 dB within 4 km.
Opto-Electronics and Communications Conference, 2008 and the 2008 Australian Conference on Optical Fibre Technology. OECC/ACOFT 2008. Joint conference of the; 08/2008
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ABSTRACT: A next generation optical access networks with a function of bilateral adaptable architecture is proposed and demonstrated. The hybrid-PON service is successfully demonstrated by both E-PON and WDM-PON with a simple uni-architecture of remote node. Furthermore, the hybrid-PON service can diagnose the health of the service with the monitoring technology in service state with the low-cost solutions.
Transparent Optical Networks, 2008. ICTON 2008. 10th Anniversary International Conference on; 07/2008
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ABSTRACT: A tunable coherent photonic microwave notch filter based on phase-shifted fiber Bragg grating is proposed. Because of the Yb3+/Al3+ codoped optical fiber between two sub-FBGs, the optical phase of the delayed signal is linearly and precisely controlled by adjusting the injected pump power at around 980 nm. By changing the optical phase shift inside the filter, notch frequency can be varied continuously keeping its free spectral range. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2409–2411, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23648
Microwave and Optical Technology Letters 06/2008; 50(9):2409 - 2411. · 0.62 Impact Factor
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ABSTRACT: We experimentally demonstrate a radio-over-fiber downlink system using a stimulated Brillouin scattering (SBS)-based photonic upconversion technique. The Brillouin selective amplification characteristic of SBS is incorporated to generate the 11-GHz band radio-frequency (RF) carrier. The dual-electrode Mach-Zehnder optical modulator, which is used to carry the broadband data in the optical carrier instead of the optical sideband, is adopted along with the SBS-based carrier generation setup. To vindicate the broadband capabilities of the proposed scheme, 1.25-Gb/s pseudorandom bit sequence data is carried in the optical carrier. Error-free operation of the 1.25-Gb/s downlink is achieved without critical power penalties after the 13-km fiber transmission.
IEEE Photonics Technology Letters 12/2007; · 2.19 Impact Factor
