4A3 (1)

Session 4A3Optics, Fiber, Lasers and Optical Sensors

Phase Control in the Ramsey Resonance Cavity with 2 Ring Cavities at both Ends by Inserting LoopAntenna Using Varactor in Series in the Rings for Cesium Beam Frequency Standard

Koji Nakagiri, Yusuke Kawano, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 700

Study of Sapphire Loaded H-Maser in Shanghai Observatory

Ke Dai, Wei Qun Zhang, Yan Jun Zhang, Wen Ming Wang, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 701

Improvements on Phase-Shifted Distributed-Coupling-Coefficient Distributed Feedback Laser Structuresfor Single Longitudinal Mode OperationJose Maria Bastardo De Miranda Boavida, Carlos Alberto Ferreira Fernandes, Jose Augusto Pas-sos Morgado, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 702

On the Performance of DFB Laser Structures Specially Designed for Directly-Modulated Optical Com-munication SystemsJose Maria Bastardo De Miranda Boavida, Carlos Alberto Ferreira Fernandes, Jose Augusto Pas-sos Morgado, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 703

Reduction of Four-wave-mixing Noises by Unequally-spaced Allocations with Dual Base Units in FDMOptical Fiber Transmission Systems

Toru Nakamura, Takahiro Numai, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 704

Reduction of Four-wave-mixing Noises by FSK Modulation with Dual Deviation Frequencies in FDMOptical Fiber Transmission Systems

Takuya Tamo, Takahiro Numai, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 705

Fabrication of Separately Formed Electro-spun Fibers

Hirohisa Tamagawa, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 706

Performance Improvement of Phase Modulation with Interferometric Detection through Low-biasing

Lan Liu, Shilie Zheng, Xianmin Zhang, Xiaofeng Jin, Hao Chi, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 707

Profile Measurement for Micro-optical Component Using Lensless Fourier Digital Holography

Yunxin Wang, Dayong Wang, Yan Li, Jie Zhao, Yizhuo Zhang, Yuhong Wan, Zhuqing Jiang, . . . 708

A Novel Data Transmission Security via a Noisy Channel Using a Microring Resonator System

Thanunchai Threepak, Somsak Mitatha, Preecha P. Yupapin, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 709

Ferroelectric Properties of BiFeO3 Thin Film Grown on LaNiO3 Buffered Si (100) Substrate via PulsedLaser Deposition

Feng Yan, Li Lu, Man On Lai, Tiejun Zhu, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 710

699

700 Progress In Electromagnetics Research Symposium Abstracts, Xian, China, March 2226, 2010

Phase Control in the Ramsey Resonance Cavity with 2 RingCavities at both Ends by Inserting Loop Antenna Using Varactorin Series in the Rings for Cesium Beam Frequency Standard

Koji Nakagiri and Yusuke KawanoKinki University, Kinokawa City, Wakayama 649-6493, Japan

Abstract A vertical cesium beam experimental frequency standard is under construction.It aims at an accuracy of around 7 1015 or less by adopting new techniques such as 4-poleelectromagnets for energy selection and beam focus including velocity selection, and a Ramseyresonance cavity in which the microwave phase of interactions with the cesium beam may becontrolled by changing the cesium beam velocity electrically by the magnet and measuring thecavity frequency shift, because the cavity phase and Doppler frequency shifts are proportional tothe cesium beam velocity.The investigation on phase control of ring cavities has been conducted, to which the microwaveis supplied through a single-U type waveguide which has a E-plane T-couple in the center and isconnected with the E-plane T-couple of ring cavity at both ends. We inserted a single or doubleloop antenna using the varactor (variable capacitance tip diode) in series to the H-plane of ringtype cavities to control the phase of the microwave and the cesium beam interaction region inthe ring cavities, respectively. The phase of ring cavity is measured by using a loop antenna.The positions of antenna are separately placed 1/4g away from a E-plane T-couple of the ringcavity, in right or left direction. The varactor loop antenna is connected in series with a coaxialsemi-rigid cable of variable length, which is shorted at the end.The frequency center of resonance in ring cavity is influenced by the varactor loop antenna inthe same ring cavity more than that in another ring cavity. This unbalance makes the differencebetween the both ring cavities by the voltage supply to the varactors, respectively.The phase difference about 2 degrees between the both detection antennas were typically obtainedby the voltage change of 10V in the case of double loop varactor antenna. In the case of singleloop varactor antenna the phase change will be less than 1 degree due to the small frequencychange between the both ring cavities. But the small power change and distortion of resonancecurve between the cavities at both ends is better for the phase control of frequency standard.

Progress In Electromagnetics Research Symposium Abstracts, Xian, China, March 2226, 2010 701

Study of Sapphire Loaded H-Maser in Shanghai Observatory

Ke Dai1, 2, Wei Qun Zhang1, Yan Jun Zhang1, and Wen Ming Wang1, 2

1Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China2Graduate School of Chinese Academy of Science, Beijing 100049, China

Abstract Sapphire loaded cavity for active H-maser was designed to minimize the mass andvolume of the traditional active H-maser. The ability of sapphire loaded cavity to achieve self-oscillation was calculated. Then we made the experiment for sapphire loaded cavity in traditionalH-maser as bed. The signal was found with oscillation power of 102 dBm while the beam fluxis about 1mA. For the temperature coefficient of sapphire loaded cavity is too high, the way tocompensate the temperature-coefficient was studied. The region of zero temperature coefficientpoint was discussed.


Improvements on Phase-Shifted Distributed-Coupling-CoefficientDistributed Feedback Laser Structures for Single Longitudinal

Mode Operation

J. Boavida1, C. Fernandes1, and J. Morgado1, 2

1Instituto de Telecomunicacoes, Portugal2Portuguese Air Force Academy, Portugal

Abstract Optical communication systems (OCS) have earned great attention from the sci-entific community, due to the increasing demand for high-bit rate data links. An OCS dependsheavily on the performance of the light emitter, usually a Distributed Feedback (DFB) laser.However, not every DFB laser structure is considered an efficient device, creating the need to op-timize, as much as possible, these structures. This paper presents optimized Phase-Shifted (PS)Distributed-Coupling-Coefficient (DCC) DFB laser structures specially designed for single lon-gitudinal mode operation in the OCS context. The optimization and analysis process is dividedinto two stages: near and above threshold.Near threshold, the purpose is simultaneously the maximization of the normalized mode selec-tivity (S) and the minimization of the electric field flatness (F ). These figures of merit are given,respectively, by S = (L) (thL) and F = 1L

L0[I(z) I]2dz, where (thL) is the normalized

threshold gain, (L) is the normalized gain of the main side mode, and I(z) is the normalizedelectric field intensity at an arbitrary position z, inside the L-length laser cavity. In order toevaluate these figures of merit, a simulation model was built using the transfer matrix method,which is based on the coupled wave equations.Above threshold, the power emission spectrum is assessed, as well as the Side Mode SuppressionRatio (SMSR). Besides, the wavelength stability with current injection is also assessed. Thismodel takes into account the undesired effects of the spatial hole burning, which deteriorate thelaser performance with increasing biasing current.The structure achieved after optimization contains a single phase-shift, and has a coupling co-efficient profile that includes three distinct values, which is designated as a 1PS-3DCC-DFBstructure. For the 1PS-3DCC-DFB, S 2.34, F 0.021 and SMSR 49 dB are achieved, aswell as a tight wavelength stability, which clearly outperforms similar laser structures proposedelsewhere, harder to manufacture.This analysis shows that, if this structure was manufactured, it could be extremely useful toattain an exceptional light emitter in the OCS context.


On the Performance of DFB Laser Structures Specially Designed forDirectly-Modulated Optical Communication Systems

J. Boavida1, C. Fernandes1, and J. Morgado1, 2

1Instituto de Telecomunicacoes, Portugal2Portuguese Air Force Academy, Portugal

Abstract Nowadays, directly-modulated (DM) distributed-feedback (DFB) lasers are playingan important role as transmitter sources in high bit rate optical-communication-systems (OCS)due to its low cost operation, small size, low dynamic voltage and high optical output power, whencompared with other transmitters using external modulation schemes. In this context, it is veryimportant to develop a suitable design for DM-DFB lasers in order to achieve a stable single-longitudinal-mode (SLM) operation with high power efficiency and ensuring the best emittedwavelength stability ( ) to avoid pulse transmission dispersion. Accordingly, it is crucial tominimize the impact of spatial-hole-burning (SHB) effect on DM-DFB lasers operation. Sucheffect is straightforwardly responsible for the degradation of both the side-mode-suppression-ratio (SMSR) and the wavelength stability.In this paper, we propose two very easily manufacturable distributed-coupling-coefficient (DCC)-DFB optimized laser structures with asymmetric facet configuration with a high-reflectivity(HR) facet and an anti-reflection (AR) facet in order to channel all the output power to theAR facet. The difference between these two structures lies on the DCC profile design, which isconsiderably more sophisticated for the second structure, enhancing the mode selectivity. Theproposed structures both present, simultaneously, high power efficiency ( 0.32WA1), tightwavelength tolerance ( 0.15 nm), a good SHB immunity (SMSR 41 dB and 1.3 105)and high yield (> 50%) that is the probability of the modal selectivity exceeding a preset value.The proposed lasers fulfill all the requirements concerning the usage of DM-DFB lasers in theOCS context. Similar performances have been recently reported but at the expense of laserstructures demanding a much more intricate fabrication process than the ones associated withthe laser structures proposed in this paper.


Reduction of Four-wave-mixing Noises by Unequally-spacedAllocations with Dual Base Units in FDM Optical Fiber

Transmission Systems

Toru Nakamura and Takahiro NumaiDepartment of Electrical and Electronic Engineering, Ritsumeikan University

1-1-1 Noji-Higashi, Kusatsu, Shiga 525-8577, Japan

Abstract Transmission characteristics in frequency-division-multiplexing (FDM) optical fibertransmission systems with low-dispersion optical fibers such as dispersion-shifted fibers (DSFs)are limited by four-wave mixing (FWM). In recent years, several FWM suppression techniquessuch as optical multiplexers and demultiplexers with the combination of delay lines, modifiedreturn-to-zero (RZ) signals, hybrid wavelength-/time-division multiplexing (WDM/TDM) tech-nique, arrangement of polarization allocations of channels, separation between signal frequenciesand the zero-dispersion frequency, combination of frequency/polarization allocations and separa-tion of signal frequencies from the zero-dispersion frequency, the hybrid amplitude-/frequency-shift keying (ASK/FSK) modulation with prechirped pulses, and unequal channel spacing havebeen reported.Characteristics of FWM are also closely related to frequency allocations and modulation formats.From the viewpoint of frequency allocations, unequally-spaced (US) allocations, repeated US(RUS) allocations, and modified RUSs such as equally-spaced RUS (ERUS) and unequally-spacedRUS (URUS) allocations have been demonstrated to overcome the problems in equally-spaced(ES) allocation. It was found that RUS, ERUS, and URUS have lower FWM light intensitieswith channel frequencies than ES and narrower total bandwidths than US. From the viewpoint ofmodulation formats, FWM noises have been analyzed for non-return-to-zero (NRZ), random RZ,differential phase-shift keying (DPSK), and bit-phase arranged RZ (BARZ) in ES, RUS, ERUS,and URUS, and it has been revealed that FWM noises are lowest in URUS with BARZ.In this paper, to reduce FWM noises further, US with dual base units, which have differ-ent frequency spacings, is proposed. It is found that the allowed input optical power is im-proved by 4.7 dB than URUS in an FDM lightwave transmission system with intensity modu-lation/direct detection. In our calculations, it is assumed that an oscillation wavelength for alight source is 1550 nm. A DSF is assumed to have the derivative dispersion coefficient dDc/dof 0.07 ps/km/nm2, the fiber length L of 80 km, and the decay rate of 0.2 dB/km. The baseunit and the channel spaces are common in all frequency allocations which are studied in thispaper, and the frequency separations are the same as those in to make the pulse delay and pulsebroadening as small as possible.

ACKNOWLEDGMENT

This research was partially supported by the Japan Society for Science, Grant-in-Aid for ScientificResearch (C) 20560379, 2009.


Reduction of Four-wave-mixing Noises by FSK Modulation withDual Deviation Frequencies in FDM Optical Fiber Transmission

Systems

Takuya Tamo and Takahiro NumaiDepartment of Electrical and Electronic Engineering, Ritsumeikan University

1-1-1 Noji-Higashi, Kusatsu, Shiga 525-8577, Japan

Abstract Transmission characteristics in frequency-division-multiplexing (FDM) optical fibertransmission systems with low-dispersion optical fibers such as dispersion-shifted fibers (DSFs)are limited by four-wave mixing (FWM). In recent years, several FWM suppression techniquessuch as optical multiplexers and demultiplexers with the combination of delay lines, modifiedreturn-to-zero (RZ) signals, hybrid wavelength-/time-division multiplexing (WDM/TDM) tech-nique, arrangement of polarization allocations of channels, separation between signal frequenciesand the zero-dispersion frequency, combination of frequency/polarization allocations and separa-tion of signal frequencies from the zero-dispersion frequency, the hybrid amplitude-/frequency-shift keying (ASK/FSK) modulation with prechirped pulses, and unequal channel spacing havebeen reported.Characteristics of FWM are also closely related to frequency allocations and modulation formats.From the viewpoint of frequency allocations, unequally-spaced (US) allocations, repeated US(RUS) allocations, and modified RUSs such as equally-spaced RUS (ERUS) and unequally-spacedRUS (URUS) allocations have been demonstrated to overcome the problems in equally-spaced(ES) allocation. It was found that RUS, ERUS, and URUS have lower FWM light intensitieswith channel frequencies than ES and narrower total bandwidths than US. From the viewpoint ofmodulation formats, FWM noises have been analyzed for non-return-to-zero (NRZ), random RZ,differential phase-shift keying (DPSK), and bit-phase arranged RZ (BARZ) in ES, RUS, ERUS,and URUS, and it has been revealed that FWM noises are lowest in URUS with BARZ.In this paper, to reduce FWM noises further, FSK modulation with dual deviation frequenciesis proposed. It is found that the crosstalk is improved by 4.9 dB, and the power penalty isimproved by 2.5 dB than FSK modulation with a single deviation frequency in an FDM lightwavetransmission system with FSK modulation/direct detection. In our calculations, it is assumedthat an oscillation wavelength for a light source is 1550 nm. A DSF is assumed to have thederivative dispersion coefficient dDc/d of 0.07 ps/km/nm2, the fiber length L of 80 km, and thedecay rate of 0.2 dB/km. The base unit and the channel spaces are common in all frequencyallocations which are studied in this paper, and the frequency separations are the same as thosein to make the pulse delay and pulse broadening as small as possible.

ACKNOWLEDGMENT

This research was partially supported by the Japan Society for Science, Grant-in-Aid for ScientificResearch (C) 20560379, 2009.


Fabrication of Separately Formed Electro-spun Fibers

Hirohisa TamagawaDepartment of Human and Information Systems, Faculty of Engineering, Gifu University, Japan

Abstract Electrospining has been known as a strong tool for the fabrication of fine polymerfibers. However, the extraction of single electro-spun fiber is a tough task. Electro-spun fibers areinevitably stick together or entangled one another during their spinning process. They cannotbe separately formed. The author of this paper found that simply placing a paper mesh betweenthe syringe needle and counter electrode of electrospinning unit, the straight fibers were sepa-rately formed between the paper mesh and counter electrode. As an ingredient of electro-spunfiber, polynorbornen was employed. Polynorbornen was dissolved into THF, and the mixture ofpolynorobornen-THF was electro-spun into short fine fibers. The resulting fibers were separatelyformed, and those fibers were extracted individually without their sticking or entangling. Theformation process of such fibers of polynorobornen was investigated. Fiber formation processwas captured by the high speed camera. It elucidated that the fiber was quite slim and wavedvehemently in the early stage of its electro-spun process, but it gradually grew fat and its dy-namic wavy motion calmed down, resulting in a bit fat straight and rigid short fiber. Using thissimple technique employing a paper mesh, the composite fibers fabrication was attempted, whichconsisted of polymer and metal powder. As the ingredients of composite fiber, polyvinylacetateand copper powder were employed. Poyvinylacetate was dissolved into THF, and subsequentlycopper powder was mixed with this polyvinylacetate-THF mixture. This composite ingredientunderwent the electrospinning process employing a paper mesh. Finally, the composite fiberswere separately formed successfully and extracted easily.


Performance Improvement of Phase Modulation withInterferometric Detection through Low-biasing

Lan Liu, Shilie Zheng, Xianmin Zhang, Xiaofeng Jin, and Hao ChiDepartment of Information Science & Electronic Engineering, Zhejiang University, Hangzhou 310027, China

Abstract Phase modulation (PM) offers many advantages in analog-photonic link. The mostimportant one is that PM neednt bias circuitry, which may not only reduce the complicationof transmitting end, but also avoid the problems caused by bias-voltage drift. Moreover, PMprovides linear conversion of input voltage to optical phase. However, suitable detection throughPM to intensity modulation (IM) conversion is needed in the phase modulated system. In thispaper, PM-to-IM is realized via interferometric detection, whose performance is improved throughtuning the laser wavelength while not complicating the system configuration.In our interferometric detection scheme, a Mach-Zehnder interferometer (MZI) composing of twocouplers and two fiber arms with different length is used. The theory of PM-to-IM throughthis interferometric detection is fully investigated, including the link gain, NF, SFDR and IP3,OIP3 (the input and output RF signal power, respectively, when the third-order intermodulationoutput equals to the fundamental output). It is said that the link gain, noise figure (NF) andspur-free dynamic range (SFDR) are related with the input optical power, laser frequency, inputRF signal frequency, link loss, and the differential delay between the two arms of the MZI. If is fixed, NF can be improved through tuning the laser wavelength. Both the theory calculationand simulation results show that there is an optimum wavelength for NF, which can be seen inFig. 1. The curve a is with input optical power of 0.1W and curve b is with input optical powerof 1W. Besides, the expression for the effective half-wave voltage of phase modulator with MZIis also developed, which only affects the value of NF, but not SFDR.

15.4915 15.4916 15.4917 15.4918 15.4919 15.4920

10

20

30

40

50

60

70

wavelength (100 nm)

NF (d

B)

b

a

Figure 1: The simulation results of NF with respected to wavelength.


Profile Measurement for Micro-optical Component Using LenslessFourier Digital Holography

Yunxin Wang, Dayong Wang, Yan Li, Jie Zhao, Yizhuo Zhang,Yuhong Wan, and Zhuqing Jiang

College of Applied Sciences, Beijing University of Technology, Beijing 100124, China

Abstract Three-dimensional (3D) profile measurement for micro-optical component has at-tracted remarkable attention recently for its wide application in many filed such as optical imag-ing, transmission and communication. Digital holography (DH) has become a research focus in3D profile reconstruction discipline in view of its high resolution, non-invasion, non-contact, andfull wave field mode. In this contribution, digital holography imaging method based on off-axislensless Fourier transform (LFT) is presented for 3D profile detection of micro-optical compo-nent. Since the phase is proportional to the height of transparent object under the conditionof constant refractive index, the quantitative 3D profile can be acquired with the combinationof phase and amplitude. Firstly, the LFT holography configuration is designed, and the ampli-tude and phase of the whole wave field are reconstructed from only a single recorded hologramby Fresnel reconstruction method. Then phase compensation is adopted to remove the quadricphase aberration, and the accurate phase information is extracted in use of the least-squaresphase-unwrapping algorithm. Finally, the performance of LFT holography imaging is validatedwith two kinds of micro-lens array, one is the spherical micro-lens array with 3.07m height and860.70m half width, and another one is cylindrical micro-lens arrays with 2.77m height and166.90m half width. Properties like lens height, radius of curvature (ROC), and surface rough-ness of micro-lens arrays are measured by LFT holography configuration. In order to verify thefeasibility and effectiveness of the developed method, we acquire and compare the profile param-eters of the aforementioned micro-lens arrays using the stylus profilometer. The results indicatethat the profile parameters obtained above are in good agreement, which demonstrates that LFTholography method provides an effective tool for 3D profile detection, and has wide applicationperspective in quality evaluation and machining guidance for micro-optical component.


A Novel Data Transmission Security via a Noisy Channel Using aMicroring Resonator System

T. Threepak1, S. Mitatha1, and P. P Yupapin2

1Hibrid Computing Research Laboratory, Faculty of EngineeringKing Mongkuts Institute of Technology Ladkrabang, Bangkok, Thailand2Advance Research Center for Photonics, Department of Applied PhysicsKing Mongkuts Institute of Technology Ladkrabang, Bangkok, Thailand

Abstract A novel verification and encryption methods using microring resonator is presented.By using the proposed system, the confidentiality and integrity of information in optical commu-nication can be formed. In this paper, chaostic noise sophisticates irreversible and unpredictablein nonlinear microring resonator that is used as the encrypted function. In our successfullysimulation results, the microring resonator and add/drop filter are uses to generate the mes-sage authentication code for maintaining data integrity. Additionally, the noisy signals/channelscreated by the microring resonator are combined with the encoded information to protect theman-in-the-middle attacks (decipher). By using the extremely small processing device, the pro-pose design can be easily applied to secure any form of communication in wireless network,mobile communication network and military applications with low power consumption and veryhigh-speed procedures.


Ferroelectric Properties of BiFeO3 Thin Film Grown on LaNiO3Buffered Si (100) Substrate via Pulsed Laser Deposition

Feng Yan1, Li Lu1, Man On Lai1, and Tiejun Zhu2

1Department of Mechanical Engineering, National University of Singapore9, Engineering Drive 1, 117576, Singapore

2Department of Materials Science and Engineering, Zhejiang UniversityHangzhou 310027, China

Abstract Ferroelectric properties of multiferroic BiFeO3 (BFO) thin films have been grownon a LaNiO3 conductive layer buffered Si (100) substrate via pulsed laser deposition method. Thecrystalline structure and surface morphology of the film were characterized by X-ray diffractionstudies and atomic force microscopy, which confirmed the strong (100) texture growth, the surfaceroughness, RMS 7.832 nm, and the polarization direction is close to 100. The BFO filmshowed a well saturated ferroelectric hysteresis loops with a remanent polarization of 55mC/cm2,and coercive field of approximately 180 kV/cm The dielectric property was obtained in a frequencyrange of 100 1MHz. The ferroelectric domain structure and piezoresponse behavior in the BFOthin film were also studies by piezoelectric force microscopy.

4A3 (1)

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