| 1. |
- Deng, Lei, et al.
(författare)
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All-VCSEL Transmitters With Remote Optical Injection for WDM-OFDM-PON
- 2014
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Ingår i: IEEE Photonics Technology Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1041-1135 .- 1941-0174. ; 26:5, s. 461-464
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Tidskriftsartikel (refereegranskat)abstract
- We report on a novel scheme that uses vertical cavity surface emitting lasers (VCSELs) and remote optical injection technique in the hybrid wavelength division multiplexing orthogonal frequency division multiplexing (OFDM) passive optical network. In the proposed scheme, 1.55-μm VCSELs are used as low-cost, directly modulated upstream and downstream transmitters. The slave VCSEL at the optical network unit is remotely injection-locked by modulated downstream signals, and no need for additional injection-locking optical sources and external modulators. In our experiment, bidirectional transmission of 1.25 Gb/s 4-quadrature amplitude modulation (4QAM)-OFDM signal over 26-km single mode fiber has been successfully demonstrated. Moreover, we investigate the residual amplitude modulation (RAM) caused by the conversion of injected AM into slave AM. In addition, the experimental results show that due to this RAM, the power penalty of the 1.25 Gb/s 4QAM-OFDM upstream transmission is deteriorated by 2 dB.
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| 2. |
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| 3. |
- Dong, Hui, et al.
(författare)
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Generalized frequency dependence of output Stokes parameters in an optical fiber system with PMD and PDL/PDG
- 2005
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Ingår i: Optics Express. - 1094-4087. ; 13:22, s. 8875-8881
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Tidskriftsartikel (refereegranskat)abstract
- Dependence of output optical power, Stokes vector and degree of polarization on optical frequency is presented for an optical fiber system with both polarization mode dispersion and polarization-dependent loss or gain. The newly formulated equations are generalized for input light with arbitrary degree of polarization. The spectral resolved measurements of polarization mode dispersion using partially polarized light agree well with our theory.
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| 4. |
- Dong, Hui, et al.
(författare)
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Generalized frequency dependence of output Stokes parameters in an optical fiber system with PMD and PDL/PDG
- 2005
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Ingår i: Optics Express. - : Optica Publishing Group. - 1094-4087. ; 13:22, s. 8875-8881
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Tidskriftsartikel (refereegranskat)abstract
- Dependence of output optical power, Stokes vector and degree of polarization on optical frequency is presented for an optical fiber system with both polarization mode dispersion and polarization-dependent loss or gain. The newly formulated equations are generalized for input light with arbitrary degree of polarization. The spectral resolved measurements of polarization mode dispersion using partially polarized light agree well with our theory.
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| 5. |
- Dong, Hui, et al.
(författare)
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Measurement of Mueller matrix for an optical fiber system with birefringence and polarization-dependent loss or gain
- 2007
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 274:1, s. 116-113
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Tidskriftsartikel (refereegranskat)abstract
- In an optical fiber system with both birefringence and polarization-dependent loss or gain (PDL/G), a set of input polarization states and their corresponding outputs are deduced to fulfill some general relationships in Stokes space, by considering the fact that the Mueller matrix of such an optical fiber system meets Lorentz transformation. Then, it can be proven that the minimum number of input polarization states is three for an explicit determination of such a Mueller matrix and no independent input parameter is redundant. Based on the theoretical findings, a general and simple approach is proposed to measure the Mueller matrix. The requirements regarding the choices of three inputs are presented for achieving optimum measurement stability and accuracy. Experimental results on an optical fiber system, formed by two 10-km long single-mode fibers with an optical isolator in between, show excellent agreement with the theory.
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| 6. |
- Dong, Hui, et al.
(författare)
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Measurement of polarization mode dispersion vectors in optical fibers using a virtual Mueller matrix method
- 2007
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Ingår i: Optical Engineering. - : SPIE-Intl Soc Optical Eng. - 0091-3286 .- 1560-2303. ; 46:3, s. 035007-
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Tidskriftsartikel (refereegranskat)abstract
- A virtual Mueller matrix method is proposed to measure the first- and second-order polarization mode dispersion (PMD) vectors in optical fibers. This method not only can use a large frequency step to attain low-noise PMD vector data, but also does not require knowledge of the input polarization states. Our measurement method has a simpler setup and is more accurate than the traditional Mueller matrix method.
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| 7. |
- Dong, Hui, et al.
(författare)
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Quasi-monochromatic fiber depolarizer and its application to polarization-dependent loss measurement
- 2006
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Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 31:7, s. 876-878
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Tidskriftsartikel (refereegranskat)abstract
- We theoretically derive the relationship between the degrees of polarization (DOPs) of input and output for an optical component with polarization-dependent loss (PDL) and birefringence. Based on the theoretical result, we propose a novel depolarizer for quasi-monochromatic light that can depolarize a fully polarized light with a 50 MHz linewidth to less than 0.2% in the DOR The depolarized light is then used to measure PDL in a single-mode optical fiber link. To the best of our knowledge, our new PDL measurement method is significantly faster than all known methods. Experimental results show excellent agreement with other methods.
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| 8. |
- Dong, Hui, et al.
(författare)
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Virtual generalized Mueller matrix method for measurement of complex polarization-mode dispersion vector in optical fibers
- 2007
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Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 19:1, s. 27-29
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Tidskriftsartikel (refereegranskat)abstract
- A virtual generalized Mueller matrix method (VGMMM) is proposed to measure the complex polarization-mode dispersion (PMD) vector in a fiber system with polarization-dependent loss or gain. VGMMM can attain the low-noise high-resolution PMD data using a relatively large frequency step, without the knowledge of input polarization states. VGMMM combines the advantages of both matrix-based methods and differentiation-based methods and overcomes their shortcomings. Experimental results on a fiber system confirm the validity and accuracy of VGMMM.
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| 9. |
- Feng, Zhenhua, et al.
(författare)
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Multicore-Fiber-Enabled WSDM Optical Access Network With Centralized Carrier Delivery and RSOA-Based Adaptive Modulation
- 2015
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Ingår i: IEEE PHOTONICS JOURNAL. - : Institute of Electrical and Electronics Engineers (IEEE). - 1943-0655. ; 7:4
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Tidskriftsartikel (refereegranskat)abstract
- We proposed and experimentally demonstrated a wavelength-space division multiplexing (WSDM) optical access network architecture with centralized optical carrier delivery utilizing multicore fibers (MCFs) and adaptive modulation based on reflective semiconductor amplifier (RSOA). In our experiment, five of the outer cores are used for undirectional downstream (DS) transmission only, whereas the remaining outer core is utilized as a dedicated channel to transmit upstream (US) signals. Optical carriers for US are delivered from the optical line terminal (OLT) to the optical network unit (ONU) via the inner core and then transmitted back to the OLT after amplification and modulation by the RSOA in the colorless ONU side. The mobile backhaul (MB) service is also supported by the inner core. Wavelengths used in US transmission should be different from that of the MB in order to avoid the Rayleigh backscattering effect in bidirectional transmission. With quadrature phase-shift keying-orthogonal frequency-division multiplexing (QPSK-OFDM) modulation format, the aggregation DS capacity reaches 250 Gb/s using five outer cores and ten wavelengths, and it can be further scaled to 1 Tb/s using 20 wavelengths modulated with 16 QAM-OFDM. For US transmission, 2.5 Gb/s QPSK-OFDM transmission can be achieved just using a low-bandwidth RSOA, and adaptive modulation is applied to the RSOA to further enhance the US data rate to 3.12 Gb/s. As an emulation of high-speed MB transmission, 48 Gb/s inphase and quadrature (IQ) modulated popularization division multiplexing (PDM)-QPSK signal is transmitted in the inner core of MCF and coherently detected in the OLT side. Both DS and US optical signals exhibit acceptable performance with sufficient power budget.
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| 10. |
- Feng, Zhenhua, et al.
(författare)
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Performance-Enhanced Direct Detection Optical OFDM Transmission With CAZAC Equalization
- 2015
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Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 27:14, s. 1507-1510
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Tidskriftsartikel (refereegranskat)abstract
- Direct detection optical orthogonal frequency division multiplexing (DDO-OFDM) transmission with constant amplitude zero autocorrelation (CAZAC) sequence equalization is proposed and experimentally demonstrated. Simulation results show that more than 2-dB peak-to-average power ratio (PAPR) reduction can be realized using CAZAC equalization, and 50-km standard single mode fiber (SSMF) transmission of 4.11-Gb/s QPSK-OFDM can be achieved with bit-error rate (BER) under forward error correction limit. Transmission performance of QPSK-based DDO-OFDM system is analyzed in both OB2B configuration and fiber link with and without CAZAC equalization. More than 2.5-dB optical receiver sensitivity improvements can be obtained thanks to the PAPR reduction enjoyed by CAZAC equalization. Signal-to-noise ratio for every subcarrier derived from error vector magnitude is estimated and its flatness is confirmed to be much improved with CAZAC equalization. The performance improvements brought by CAZAC equalization can be extended to other modulation formats, and 8.22-Gb/s 16-quadratic-amplitude modulation-OFDM signals transmission using CAZAC equalization is demonstrated with over 1.5 dB enhancement in receiver sensitivity.
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| 11. |
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| 12. |
- Liu, Hairong, et al.
(författare)
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Design and analysis of anti-resonant reflecting photonic crystal VCSEL lasers
- 2004
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Ingår i: Optics Express. - 1094-4087. ; 12:18, s. 4269-4274
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Tidskriftsartikel (refereegranskat)abstract
- Anti-resonant reflecting photonic crystal structure is employed in vertical cavity surface emitting lasers (VCSELs) to achieve photon confinement in lateral direction. Such a design is promising in supporting large-aperture single-mode emission. In the configuration, hexagonal arrays of high-index cylinders which run vertically in the cladding region are introduced in the VCSEL's top DBR (p-DBR) mirror region. The transverse modal property of the proposed structure, especially leakage loss, has been theoretically investigated. An optimum design for the minimum radiation loss while maintaining single-mode operation has been discussed in this paper.
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| 13. |
- Liu, Hairong, et al.
(författare)
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Design and analysis of anti-resonant reflecting photonic crystal VCSEL lasers
- 2004
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Ingår i: Optics Express. - : Optical Society of America. - 1094-4087. ; 12:18, s. 4269-4274
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Tidskriftsartikel (refereegranskat)abstract
- Anti-resonant reflecting photonic crystal structure is employed in vertical cavity surface emitting lasers (VCSELs) to achieve photon confinement in lateral direction. Such a design is promising in supporting large-aperture single-mode emission. In the configuration, hexagonal arrays of high-index cylinders which run vertically in the cladding region are introduced in the VCSEL’s top DBR (p-DBR) mirror region. The transverse modal property of the proposed structure, especially leakage loss, has been theoretically investigated. An optimum design for the minimum radiation loss while maintaining single-mode operation has been discussed in this paper.
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| 14. |
- Liu, Hairong, et al.
(författare)
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Optimum design of anti-resonant reflecting photonic crystal vertical-cavity surface-emitting lasers
- 2005
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Ingår i: Chinese Optics Letters. - 1671-7694. ; 3:SUPPL, s. S210-S212
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Tidskriftsartikel (refereegranskat)abstract
- Anti-resonant reflecting photonic crystal structure in vertical-cavity surface-emitting lasers (VCSELs) to achieve photon confinement in lateral direction is introduced. This kind of design is proposed to support large aperture single-mode emission. A proper method to fabricate the proposed structure has also been discussed. Firstly a spacer layer will be fabricated between the active layer and pDBR layer. A hexagonal array of high-index cylinders will be designed by etching and re-growth on the spaced layer. The transverse modal property of the proposed structure has been investigated. An optimum design for the minimum radiation loss by considering of the cylinder diameter has been discussed in this paper.
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| 15. |
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| 16. |
- Ren, Guobin, et al.
(författare)
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Design of all-solid bandgap fiber with improved confinement and bend losses
- 2006
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Ingår i: IEEE Photonics Technology Letters. - : IEEE. - 1041-1135 .- 1941-0174. ; 18:24, s. 2560-2562
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Tidskriftsartikel (refereegranskat)abstract
- We propose a new design of low-contrast all-solid bandgap fiber with low confinement and bend losses within low-order bandgaps. By introducing an index depressed layer around the high index rod in fiber cladding, we theoretically predict that the confinement loss of the proposed all-solid bandgap fiber would be significantly improved. Due to the enlarged index mismatch of the guided core mode and the edge of the bandgaps, the critical bend radius of the proposed fiber is remarkably reduced.
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| 17. |
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| 18. |
- Song, Yi, 1983-
(författare)
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Plasmonic waveguides and resonators for optical communication applications
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Photonic circuits can transmit data signals in a much higher speed thanconventional electronic circuits. However, miniaturization of photonic circuitsand devices is hindered by the existence of light diffraction limit. A promisingsolution to this problem is by exploiting plasmonic systems for guiding andmanipulating signals at optical frequencies. Plasmonic devices are generallycomposed of noble metals and dielectrics, whose interfaces can confine surfaceplasmon polaritons, a hybrid wave that is free of diffraction limit. Plasmonicwaveguides and devices are serious contenders for achieving next-generationphotonic integrated circuits with a density comparable to the electronic counterpart. This thesis addresses the design issues of passive plasmonic devices whichare critical for realization of photonic integration, including plasmonic waveguides,splitters, couplers, and resonators, investigated with both the finitedifferencetime-domain method and the finite-element method. In particularwe present, firstly, a coupler which efficiently couples light between a silicondielectric waveguide and a hybrid plasmonic (HP) waveguide. A coupling efficiencyas high as 70% is realized with a HP taper as short as 0.4μm. Theexperimental result agrees well with the numerical simulation. Secondly, wenumerically investigate and optimize the performances of 1×2 and 1×3 HPmultimode interferometers (MMIs), which split light from a silicon waveguideto multiple HP waveguides. Total transmission over 75% can be achieved inboth cases. Thirdly, we study the coupling and crosstalk issues in plasmonicwaveguide systems. Several methods for crosstalk reduction are proposed.Finally, HP nanodisk micro-cavities are designed and are numerically characterized.With a radius of 1μm, a high quality factor of 819 and a highPurcell factor of 1827 can be simultaneously achieved, which can be useful forrealizing efficient nano-lasers.
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| 19. |
- Wang, Jing, 1982-
(författare)
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Fabrication and Characterization of Photonic Crystals, Optical Metamaterials and Plasmonic Devices
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Nanophotonics is an emerging research field that deals with interaction between light and matter in a sub-micron length scale. Nanophotonic devices have found an increasing number of applications in many areas including optical communication, microscopy, sensing, and solar energy harvesting especially during the past two decades. Among all nanophotonic devices, three main areas, namely photonic crystals, optical metamaterials and plasmonic devices, gain dominant interest in the photonic society owning to their potential impacts. This thesis studies the fabrication and characterization of three types of novel devices within the above-mentioned areas. They are respectively photonic-crystal (PhC) surface-mode microcavities, optical metamaterial absorbers, and plasmonic couplers. The devices are fabricated with modern lithography-based techniques in a clean room environment. This thesis particularly describes the critical electron-beam lithography step in detail; the relevant obstacles and corresponding solutions are addressed. Device characterizations mainly rely on two techniques: a vertical fiber coupling system and a home-made optical transmissivity/reflectivity setup. The vertical fiber coupling system is used for characterizing on-chip devices intended for photonic integrations, such as PhC surface-mode cavities and plasmonic couplers. The transmissivity/reflectivity setup is used for measuring the absorbance of metamaterial absorbers. This thesis presents mainly three nanophotonic devices, from fabrication to characterization. First, a PhC surface-mode cavity on a SOI structure is demonstrated. Through a side-coupling scheme, a system quality-factor of 6200 and an intrinsic quality-factor of 13400 are achieved. Such a cavity can be used as ultra-compact optical filter, bio-sensor and etc. Second, an ultra-thin, wide-angle metamaterial absorber at optical frequencies is realized. Experimental results show a maximum absorption peak of 88% at the wavelength of ~1.58μm. The ultra-fast photothermal effect possessed by such noble-metal-based nanostructure can potentially be exploited for making better solar cells. Finally, we fabricated an efficient coupler that channels light from a conventional dielectric waveguide to a subwavelength plasmonic waveguides and vice versa. Such couplers can combine low-loss dielectric waveguides and lossy plasmonic components onto one single chip, making best use of the two.
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| 20. |
- Wang, Ruoxu, et al.
(författare)
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Demonstration of Programmable In-Band OSNR Monitoring Using LCFBG With Commercial Thermal Printer Head
- 2015
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Ingår i: IEEE PHOTONICS JOURNAL. - : Institute of Electrical and Electronics Engineers (IEEE). - 1943-0655. ; 7:4
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Tidskriftsartikel (refereegranskat)abstract
- We proposed and experimentally demonstrated a programmable optical signal-to-noise ratio (OSNR) monitoring scheme by using linearly chirped fiber Bragg grating (LCFBG) and a commercial thermal printer head. For the coherent optical orthogonal frequency-division multiplexing (CO-OFDM) transmission system, the monitor's working wavelength can be flexibly software-controlled from 1530 to 1538 nm to support standard ITU-T grid or flex-grid operation. The linear OSNR monitoring range has been achieved from 9 to 26 dB for a 16-quadrature amplitude modulation (QAM) OFDM transmission system with negligible errors, respectively. Neither chromatic dispersion nor polarization mode dispersion affect the monitoring accuracy of our system.
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| 21. |
- Wang, R., et al.
(författare)
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Electrically programmable all-fiber structured second order optical temporal differentiator
- 2015
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Ingår i: IEEE Photonics Journal. - 1943-0655. ; 7:3
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Tidskriftsartikel (refereegranskat)abstract
- We propose and experimentally demonstrate an electrically programmable second order optical temporal differentiator (OTD) based on linearly chirped fiber Bragg grating (LCFBG) and digital thermal print head (TPH). For the high-speed optical signal with 25-GHz repetition rate, an efficient second-order OTD has been achieved for arbitrary wavelength and bandwidth with the software-defined TPH configurations. By optimizing the thermooptic effect induced optical phase change in the LCFBG, the central wavelength of the differentiator can be reconfigured flexibly from 1543.5 to 1561.7 nm, with a step size of 0.114 nm. By dynamically controlling the heating elements bonded with the LCFBG, optical pulses with 0.55- and 0.8-nm 3-dB bandwidths have been successfully processed with acceptable deviation compared with the theoretical calculations.
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