An in-fiber Mach-Zehnder interferometer is proposed for the discrimination of strain and temperature.The sensor is based on two cascaded standard single mode fibers using three peanut tapers fabricated by simple splic...An in-fiber Mach-Zehnder interferometer is proposed for the discrimination of strain and temperature.The sensor is based on two cascaded standard single mode fibers using three peanut tapers fabricated by simple splicing.The cascaded structure excites more frequency components,which induce four sets of interference dips in the transmission spectrum.One set of the spectrum dips have different sensitivities to temperature and strain from those of the other three.The sensor can discriminate strain and temperature by monitoring the wavelength shifts of two spectrum dips.Repeated experiments are taken both for strain and temperature increasing and decreasing scenarios.Experimental results show that Dip 1 has an average strain sensitivity of-0.911 pm/με and an average temperature sensitivity of 49.98pm/℃.The strain sensitivity for Dip 2 is negligible and its average temperature sensitivity is 60.52pm/℃.The strain and temperature resolutions are±3.82με and±0.33℃.展开更多
Proposed is a novel optical pulse compression technique based on high-doped erbium fiber amplifier and standard single-mode fiber(SMF). We used the amplifier with the erbium ion concentration of 6.3×10-3 to ampli...Proposed is a novel optical pulse compression technique based on high-doped erbium fiber amplifier and standard single-mode fiber(SMF). We used the amplifier with the erbium ion concentration of 6.3×10-3 to amplify a hyperbolic secant pulse from a regeneratively mode-locked fiber laser. The central wavelength, pulsewidth and peak power of the pulse are 1 550 nm, 12.5 ps and 3 mW, respectively. Then the amplified pulse with peak power level corresponding to a higher-order soliton is compressed when it propagates through a 3-km-long single-mode fiber. Studied are the compressed pulses under different pump powers and fiber lengths. The results show that it can get a narrower pulse, and solve the difficulty that pulses at low power can not be compressed directly in the fiber. And the construct is compact.展开更多
This paperdetails experimental work done to quantify stress measurements made optically utilizing ordinary single mode optical fibers. Strain-induced changes of birefringence for ordinary single mode optical fiber res...This paperdetails experimental work done to quantify stress measurements made optically utilizing ordinary single mode optical fibers. Strain-induced changes of birefringence for ordinary single mode optical fiber responses are characterized against standard stress measurements in a well understand configuration. The experimental scheme for this work and the results are presented in detaial. In this paper, POssible applications for this transverse stress character of single mode fibers are also proposed.展开更多
Gradient-index rod lens (GRIN-lens) whose pitch is ordinary value with bevel ferrule coupling system is analyzed, an equivalent method which can be used to analyze this system is put forward, and a general formula for...Gradient-index rod lens (GRIN-lens) whose pitch is ordinary value with bevel ferrule coupling system is analyzed, an equivalent method which can be used to analyze this system is put forward, and a general formula for determining the coupling loss with axes mismatch, radial mismatch, and angular mismatch is derived by use of the Gaussian field approximation and mode-field coupling theory. The experimental results are in good agreement with the theory prediction. It indicates that these formulas are suitable to analyze the gradient-index rod lens coupling system with pigtail fiber.展开更多
The phenomenon of stochastic resonance (SR) is found in a single-mode laser system driven by the colored pump noise with signal modulation and the quantum noise with cross-correlation between the real and imaginary pa...The phenomenon of stochastic resonance (SR) is found in a single-mode laser system driven by the colored pump noise with signal modulation and the quantum noise with cross-correlation between the real and imaginary parts. When the net gain a0 changes, it is found that, 1) the shape of the curve of the signal-to-noise ratio (SNR) versus the pump noise self-correlation time τ exhibits a changing process of multiform SR, from single-peak SR, to simultaneous existence of resonances and suppressions; 2) the curve of SNR. versus signal frequency Ω experiences a complicated changing process from the monotonous descending to the simultaneous appearances of a maximum and a minimum, and finally to monotonous descending; 3) the curve of SNR versus cross-correlation coefficient between the real and imaginary parts of the quantum noise λq appears an acute single-peak SR. Therefore, the net gain ao greatly influences the characteristic of SR of laser system.展开更多
A cladding-pumped ytterbium-doped fiber laser is described in this letter. Using unusual pumping source with 915-nm wavelength, slope efficiency up to 75% with respect to absorbed input power and output power is obtai...A cladding-pumped ytterbium-doped fiber laser is described in this letter. Using unusual pumping source with 915-nm wavelength, slope efficiency up to 75% with respect to absorbed input power and output power is obtained, a maximum output power of 4.006 W with fundamental mode is measured.展开更多
Spectral characteristics of the amplified spontaneous emission (ASE) from a novel single mode Er^(3+) doped tellurite fiber with D-type cladding is reported in this letter. When pumped at 980 nm, an ASE source that ha...Spectral characteristics of the amplified spontaneous emission (ASE) from a novel single mode Er^(3+) doped tellurite fiber with D-type cladding is reported in this letter. When pumped at 980 nm, an ASE source that has nearly a 100-nm flat FWHM bandwidth is obtained with a fiber length of 30-60 cm. Variation of ASE spectra with pump powers and fiber lengths are measured. Output power up to 2.0 mW is obtained with a launched pump power of 660 mW.展开更多
We experimentally investigate an optimum scheme of coupling a collimated light from a Ti:sapphire laser source into a standard single-mode fiber (SMF). By adjusting the effective numerical aperture (NA) of coupli...We experimentally investigate an optimum scheme of coupling a collimated light from a Ti:sapphire laser source into a standard single-mode fiber (SMF). By adjusting the effective numerical aperture (NA) of coupling lens and eliminating the chromatic aberration, a coupling efficiency of around 70% is finally obtained. This result is close to the maximum value predicted by theoretical simulation. It is well demonstrated that high coupling efficiency between Ti:sapphire laser and SMF can also be obtained by optimizing certain parameters of a coupling lens, without employing any special optical components, or the specific fiber with complex structure.展开更多
This paper presents the design and analysis of optical filters that are placed at the output of directly modulated vertical cavity surface emitting laser (VCSEL) in the process of inexpensive transmitter's implemen...This paper presents the design and analysis of optical filters that are placed at the output of directly modulated vertical cavity surface emitting laser (VCSEL) in the process of inexpensive transmitter's implementation for upcoming generation optical access network. Generation of non return to zero (NRZ) optical signal from the transmitter for 110 km error-free single mode fiber (SMF) transmission at 10 Gb/s with bit error rate (BER) of 10-30 in the absence of the external modulator and encoder was proposed. Effects of super-Gaussian and Butterworth optical filters at VCSEL output were demonstrated to maximize performance of SMF optical systems without need of any dispersion compensation technique.展开更多
In this paper,an efficient 8-channel 32Gbps RoF(Radio over Fiber)system incorporating Bessel Filter(8/32 RoFBF)has been demonstrated to reduce the impact of non-linear transmission effects,specifically Four-Wave Mixin...In this paper,an efficient 8-channel 32Gbps RoF(Radio over Fiber)system incorporating Bessel Filter(8/32 RoFBF)has been demonstrated to reduce the impact of non-linear transmission effects,specifically Four-Wave Mixing(FWM).The simulation results indicate that the proposed 8/32 RoF-BF system provides an optimum result w.r.t.channel spacing(75 GHz),input source power(0 dBm)and number of input channels(8).In comparison with the existing RoF system,the proposed 8/32 RoF-BF system has been validated analytically and it is found that the performance of the proposed system is in close proximity particularly in FWM sideband power reduction of the order of 4 dBm for the 8-channel 32Gbps RoF system.展开更多
A frequency domain analysis is presented to determine the performance characteristics of a tunable all-optical wavelength converter using four-wave mixing (FWM) in a single mode fiber (SMF) around the zero dispersion ...A frequency domain analysis is presented to determine the performance characteristics of a tunable all-optical wavelength converter using four-wave mixing (FWM) in a single mode fiber (SMF) around the zero dispersion wavelength using two pump lasers. The output converted signal power as well as efficiency evaluated at a bit rate of 10 Gb/s show that the signal power is substantially higher at lower values of wavelength separation.展开更多
Transmission of 40Gbit/s NRZ signal was successfully demonstrated over 219km of installed SMF in KT's Daejeon area network. After transmission, the measured power penalty was 0.5dB for all the tributary channels.
The fiber Bragg grating (FBG) is a passive optical fiber component with the refractive index modulated along the fiber length and has been widely applied in fiber sensing systems. High-temperature stable fiber grati...The fiber Bragg grating (FBG) is a passive optical fiber component with the refractive index modulated along the fiber length and has been widely applied in fiber sensing systems. High-temperature stable fiber gratings are promising for uses at high temperatures and attract extensive attention. In this paper, FBGs were inscribed in hydrogen loaded standard single mode fibers with the 248-nm excimer laser, and regenerated gratings were obtained through heat treatment. The shift of the central wavelength of the regenerated FBG had a good linearity with temperature, and the reflectivity of the regenerated FBG could almost keep unchanged at 800 ℃.展开更多
The modulation phase shift method was used to measure chromatic dispersion in a standard single mode fiber for telecommunication. The modulation phase difference of the transmitted light at the wavelength of 1532.16 n...The modulation phase shift method was used to measure chromatic dispersion in a standard single mode fiber for telecommunication. The modulation phase difference of the transmitted light at the wavelength of 1532.16 nm modulated by a radio frequency signal was measured, relative to the transmitted light at the wavelength of 1549.33 nm modulated by the same signal. By introducing a reference light at the wavelength of 1310 nm, a 1310/1550 nm wavelength division multiplexing was used instead of the high cost dense wavelength division multiplexing. In the experiment, two testing lights were coupled with the reference light to the fiber spools of different lengths, respectively. By finite difference method, the chromatic dispersion between the two testing lights was measured, and the fixed errors generated during transmission were less than 0.5 ps/(nm·km).展开更多
A 10 Gbit/s recirculating system is configured with Chirped Fiber Bragg Grating (CFBG) for the dispersion compensation. For the first time, the transmission distance in the loop reaches 1000km with bit error rate of 1...A 10 Gbit/s recirculating system is configured with Chirped Fiber Bragg Grating (CFBG) for the dispersion compensation. For the first time, the transmission distance in the loop reaches 1000km with bit error rate of 10-9. The effect of the group delay ripple of the fiber grating is also investigated in the recirculating systems, and it is shown that the transmission distance is limited to 4 cycles (4× 167.1km ) in the loop with the power penalty fluctuation below 1.0dB. Thus the group delay ripple should be reduced to allow for the wavelength drift of ±5GHz.At the end of this letter, the principles are given for designing long haul recirculating systems with dispersion compensation CFBG.展开更多
The synthetic effects of group-velocity mismatch and cubic-quintic nonlinearity on cross-phase modulation induced modulation instability in loss single-mode optical fibers have been numerically investigated. The resul...The synthetic effects of group-velocity mismatch and cubic-quintic nonlinearity on cross-phase modulation induced modulation instability in loss single-mode optical fibers have been numerically investigated. The results show that the quintic nonlinearity plays a role similar to the case of neglecting the group-velocity mismatch in modifying the modulation instability, namely, the positive and negative quintic nonlinearities can still enhance and weaken the modulation instability, respectively. The group-velocity mismatch can considerably change the gain spectrum of modulation instability in terms of its shape, peak value, and position. In the normal dispersion regime, with the increase of the group-velocity mismatch parameter, the gain spectrum widens and then narrows, shifts to higher frequencies, and the peak value gets higher before approaching a saturable value. In the abnormal dispersion regime, two separated spectra may occur when the group-velocity mismatch is taken into account. With the increase of the group-velocity mismatch parameter, the peak value of the gain spectrum gets higher and shorter before tending to a saturable value for the first and second spectral regimes, respectively.展开更多
We demonstrate a novel 40-Gb/s transmission system over a 10×101-km standard single mode fiber (SSMF) loop. This system features polarization multiplexed quadrature phase shift keying (PolMux-QPSK), lowvoltag...We demonstrate a novel 40-Gb/s transmission system over a 10×101-km standard single mode fiber (SSMF) loop. This system features polarization multiplexed quadrature phase shift keying (PolMux-QPSK), lowvoltage modulation of 2-V peak-to-peak signal amplitude, and home-made 90° optical hybrid with singleended digital coherent detection. Any power amplifers before the modulator and balanced detectors are not used. In the case of low-voltage modulation, coherent detection is much less sensitive to modulator bias offset than delay interferometer-based demodulation.展开更多
We propose the single feeder fiber architecture for wavelength division multiplexing passive optical network(WDM-PON)based on directly modulated chirp managed laser(CML).The downlink(DL)signal output from the laser is...We propose the single feeder fiber architecture for wavelength division multiplexing passive optical network(WDM-PON)based on directly modulated chirp managed laser(CML).The downlink(DL)signal output from the laser is converted to return-to-zero(RZ)differential phase shift signal using a pulse carver.The downstream signal is reused as a carrier for the upstream using intensity modulation technique.Simulation results show the error-free performance at symmetric data rate of 10 Gbit/s per channel with negligible power penalty and improved receiver sensitivity for the uplink(UL),over 25 km standard single-mode fiber(SSMF).A low-cost and reduced circuitry network design is implemented on a single feeder fiber with the elimination of differential encoder and one external modulator.展开更多
In this paper,a novel refractive index(RI) sensor is proposed based on the fused tapered special multi-mode fiber(SMMF).Firstly,a section of SMMF is spliced between two single-mode fibers(SMFs).Then,the SMMF is proces...In this paper,a novel refractive index(RI) sensor is proposed based on the fused tapered special multi-mode fiber(SMMF).Firstly,a section of SMMF is spliced between two single-mode fibers(SMFs).Then,the SMMF is processed by a fused tapering machine,and a tapered fiber structure is fabricated.Finally,a fused tapered SMMF sensor is obtained for measuring external RI.The RI sensing mechanism of tapered SMMF sensor is analyzed in detail.For different fused tapering lengths,the experimental results show that the RI sensitivity can be up to 444.517 81 nm/RIU in the RI range of 1.334 9—1.347 0.The RI sensitivity is increased with the increase of fused tapering length.Moreover,it has many advantages,including high sensitivity,compact structure,fast response and wide application range.So it can be used to measure the solution concentration in the fields of biochemistry,health care and food processing.展开更多
We propose a stable multi-longitudinal Brillouin/semiconductor fiber laser (BSFL) as the upstream source in a bidirectional single-fiber wavelength-division multiplexing-passive optical network (WDM-PON). The down...We propose a stable multi-longitudinal Brillouin/semiconductor fiber laser (BSFL) as the upstream source in a bidirectional single-fiber wavelength-division multiplexing-passive optical network (WDM-PON). The downstream wavelength serves as the pump of the BSFL. Brillouin-frequency-shifted (-10.8 GHz) upstream carrier is generated to suppress the Rayleigh backscattering and back reflection-induced crosstalk. The stable multi-longitudinal operation of the BSFL, attributed to the four-wave mixing (FWM) effect in the semiconductor optical amplifier (SOA) reduces the difficulty of generating a stable single-longitudinal fiber laser-based upstream carrier. Bidirectional symmetric transmission at 10 Gb/s over a 12.5-km single mode fiber with less than 2-dB power penalty is demonstrated.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.62005011,61801017,and.62005013)the Beijing Municipal Natural Science Foundation(Grant No.4212009)the Fundamental Research Funds for the Central Universities(Grant No.2020RC015).
文摘An in-fiber Mach-Zehnder interferometer is proposed for the discrimination of strain and temperature.The sensor is based on two cascaded standard single mode fibers using three peanut tapers fabricated by simple splicing.The cascaded structure excites more frequency components,which induce four sets of interference dips in the transmission spectrum.One set of the spectrum dips have different sensitivities to temperature and strain from those of the other three.The sensor can discriminate strain and temperature by monitoring the wavelength shifts of two spectrum dips.Repeated experiments are taken both for strain and temperature increasing and decreasing scenarios.Experimental results show that Dip 1 has an average strain sensitivity of-0.911 pm/με and an average temperature sensitivity of 49.98pm/℃.The strain sensitivity for Dip 2 is negligible and its average temperature sensitivity is 60.52pm/℃.The strain and temperature resolutions are±3.82με and±0.33℃.
基金National Natural Science Foundation of China(60507001 60477022 06YFGPGX08500)
文摘Proposed is a novel optical pulse compression technique based on high-doped erbium fiber amplifier and standard single-mode fiber(SMF). We used the amplifier with the erbium ion concentration of 6.3×10-3 to amplify a hyperbolic secant pulse from a regeneratively mode-locked fiber laser. The central wavelength, pulsewidth and peak power of the pulse are 1 550 nm, 12.5 ps and 3 mW, respectively. Then the amplified pulse with peak power level corresponding to a higher-order soliton is compressed when it propagates through a 3-km-long single-mode fiber. Studied are the compressed pulses under different pump powers and fiber lengths. The results show that it can get a narrower pulse, and solve the difficulty that pulses at low power can not be compressed directly in the fiber. And the construct is compact.
文摘This paperdetails experimental work done to quantify stress measurements made optically utilizing ordinary single mode optical fibers. Strain-induced changes of birefringence for ordinary single mode optical fiber responses are characterized against standard stress measurements in a well understand configuration. The experimental scheme for this work and the results are presented in detaial. In this paper, POssible applications for this transverse stress character of single mode fibers are also proposed.
文摘Gradient-index rod lens (GRIN-lens) whose pitch is ordinary value with bevel ferrule coupling system is analyzed, an equivalent method which can be used to analyze this system is put forward, and a general formula for determining the coupling loss with axes mismatch, radial mismatch, and angular mismatch is derived by use of the Gaussian field approximation and mode-field coupling theory. The experimental results are in good agreement with the theory prediction. It indicates that these formulas are suitable to analyze the gradient-index rod lens coupling system with pigtail fiber.
基金This work was supported by the National Natural Science Foundation of China under Grant No. 10275025.
文摘The phenomenon of stochastic resonance (SR) is found in a single-mode laser system driven by the colored pump noise with signal modulation and the quantum noise with cross-correlation between the real and imaginary parts. When the net gain a0 changes, it is found that, 1) the shape of the curve of the signal-to-noise ratio (SNR) versus the pump noise self-correlation time τ exhibits a changing process of multiform SR, from single-peak SR, to simultaneous existence of resonances and suppressions; 2) the curve of SNR. versus signal frequency Ω experiences a complicated changing process from the monotonous descending to the simultaneous appearances of a maximum and a minimum, and finally to monotonous descending; 3) the curve of SNR versus cross-correlation coefficient between the real and imaginary parts of the quantum noise λq appears an acute single-peak SR. Therefore, the net gain ao greatly influences the characteristic of SR of laser system.
文摘A cladding-pumped ytterbium-doped fiber laser is described in this letter. Using unusual pumping source with 915-nm wavelength, slope efficiency up to 75% with respect to absorbed input power and output power is obtained, a maximum output power of 4.006 W with fundamental mode is measured.
基金This work was supported by the Rising-Star Project (No. 04QMX1488)of Shanghai Municipal Science and Technology Commission and the National Natural Science Foundation of China(No. 60207006).
文摘Spectral characteristics of the amplified spontaneous emission (ASE) from a novel single mode Er^(3+) doped tellurite fiber with D-type cladding is reported in this letter. When pumped at 980 nm, an ASE source that has nearly a 100-nm flat FWHM bandwidth is obtained with a fiber length of 30-60 cm. Variation of ASE spectra with pump powers and fiber lengths are measured. Output power up to 2.0 mW is obtained with a launched pump power of 660 mW.
基金supported by the"Hundreds of Talents Programs"of Chinese Academy of Sciences(No.J08-029)the Innovative Project of Chinese Academy of Sciences(No.YYYJ-1123-4)+1 种基金the National Basic Research Program of China(No.2007CB310405)the CAS/SAFEA International Partnership Program for Creative Research Teams
文摘We experimentally investigate an optimum scheme of coupling a collimated light from a Ti:sapphire laser source into a standard single-mode fiber (SMF). By adjusting the effective numerical aperture (NA) of coupling lens and eliminating the chromatic aberration, a coupling efficiency of around 70% is finally obtained. This result is close to the maximum value predicted by theoretical simulation. It is well demonstrated that high coupling efficiency between Ti:sapphire laser and SMF can also be obtained by optimizing certain parameters of a coupling lens, without employing any special optical components, or the specific fiber with complex structure.
文摘This paper presents the design and analysis of optical filters that are placed at the output of directly modulated vertical cavity surface emitting laser (VCSEL) in the process of inexpensive transmitter's implementation for upcoming generation optical access network. Generation of non return to zero (NRZ) optical signal from the transmitter for 110 km error-free single mode fiber (SMF) transmission at 10 Gb/s with bit error rate (BER) of 10-30 in the absence of the external modulator and encoder was proposed. Effects of super-Gaussian and Butterworth optical filters at VCSEL output were demonstrated to maximize performance of SMF optical systems without need of any dispersion compensation technique.
文摘In this paper,an efficient 8-channel 32Gbps RoF(Radio over Fiber)system incorporating Bessel Filter(8/32 RoFBF)has been demonstrated to reduce the impact of non-linear transmission effects,specifically Four-Wave Mixing(FWM).The simulation results indicate that the proposed 8/32 RoF-BF system provides an optimum result w.r.t.channel spacing(75 GHz),input source power(0 dBm)and number of input channels(8).In comparison with the existing RoF system,the proposed 8/32 RoF-BF system has been validated analytically and it is found that the performance of the proposed system is in close proximity particularly in FWM sideband power reduction of the order of 4 dBm for the 8-channel 32Gbps RoF system.
文摘A frequency domain analysis is presented to determine the performance characteristics of a tunable all-optical wavelength converter using four-wave mixing (FWM) in a single mode fiber (SMF) around the zero dispersion wavelength using two pump lasers. The output converted signal power as well as efficiency evaluated at a bit rate of 10 Gb/s show that the signal power is substantially higher at lower values of wavelength separation.
文摘Transmission of 40Gbit/s NRZ signal was successfully demonstrated over 219km of installed SMF in KT's Daejeon area network. After transmission, the measured power penalty was 0.5dB for all the tributary channels.
基金This work was supported by the Major Program of the National Natural Science Foundation of China (Grant No. 61290311).
文摘The fiber Bragg grating (FBG) is a passive optical fiber component with the refractive index modulated along the fiber length and has been widely applied in fiber sensing systems. High-temperature stable fiber gratings are promising for uses at high temperatures and attract extensive attention. In this paper, FBGs were inscribed in hydrogen loaded standard single mode fibers with the 248-nm excimer laser, and regenerated gratings were obtained through heat treatment. The shift of the central wavelength of the regenerated FBG had a good linearity with temperature, and the reflectivity of the regenerated FBG could almost keep unchanged at 800 ℃.
基金Doctoral Foundation of Education Ministry of China(No 20040056008) National Natural Science Foundation ofChina (No 50539060)
文摘The modulation phase shift method was used to measure chromatic dispersion in a standard single mode fiber for telecommunication. The modulation phase difference of the transmitted light at the wavelength of 1532.16 nm modulated by a radio frequency signal was measured, relative to the transmitted light at the wavelength of 1549.33 nm modulated by the same signal. By introducing a reference light at the wavelength of 1310 nm, a 1310/1550 nm wavelength division multiplexing was used instead of the high cost dense wavelength division multiplexing. In the experiment, two testing lights were coupled with the reference light to the fiber spools of different lengths, respectively. By finite difference method, the chromatic dispersion between the two testing lights was measured, and the fixed errors generated during transmission were less than 0.5 ps/(nm·km).
基金the National 863 High Technology Development Program of China (No.2001 AA122012)
文摘A 10 Gbit/s recirculating system is configured with Chirped Fiber Bragg Grating (CFBG) for the dispersion compensation. For the first time, the transmission distance in the loop reaches 1000km with bit error rate of 10-9. The effect of the group delay ripple of the fiber grating is also investigated in the recirculating systems, and it is shown that the transmission distance is limited to 4 cycles (4× 167.1km ) in the loop with the power penalty fluctuation below 1.0dB. Thus the group delay ripple should be reduced to allow for the wavelength drift of ±5GHz.At the end of this letter, the principles are given for designing long haul recirculating systems with dispersion compensation CFBG.
基金the Fundamental Application Research Project Supported by the Science and Technology Department of Sichuan Province(No.05JY029-084,04JY029-103)the Major Project of Natural Science Supported by the Education Department of Sichuan Province(No.2006A124)and the Science and Technology Development Foundation of Chengdu University of Information Technology(No.KYTZ20060604).
文摘The synthetic effects of group-velocity mismatch and cubic-quintic nonlinearity on cross-phase modulation induced modulation instability in loss single-mode optical fibers have been numerically investigated. The results show that the quintic nonlinearity plays a role similar to the case of neglecting the group-velocity mismatch in modifying the modulation instability, namely, the positive and negative quintic nonlinearities can still enhance and weaken the modulation instability, respectively. The group-velocity mismatch can considerably change the gain spectrum of modulation instability in terms of its shape, peak value, and position. In the normal dispersion regime, with the increase of the group-velocity mismatch parameter, the gain spectrum widens and then narrows, shifts to higher frequencies, and the peak value gets higher before approaching a saturable value. In the abnormal dispersion regime, two separated spectra may occur when the group-velocity mismatch is taken into account. With the increase of the group-velocity mismatch parameter, the peak value of the gain spectrum gets higher and shorter before tending to a saturable value for the first and second spectral regimes, respectively.
基金supported in part by the National Natural Science Foundation of China (No. 60932004)the "863" Project of China (Nos. 2009AA01Z223 and 2009AA01Z253)the Open Fund of the Key Lab-oratory of Information Photonics and Optical Commu-nications (Beijing University of Posts and Telecommu-nications), Ministry of Education
文摘We demonstrate a novel 40-Gb/s transmission system over a 10×101-km standard single mode fiber (SSMF) loop. This system features polarization multiplexed quadrature phase shift keying (PolMux-QPSK), lowvoltage modulation of 2-V peak-to-peak signal amplitude, and home-made 90° optical hybrid with singleended digital coherent detection. Any power amplifers before the modulator and balanced detectors are not used. In the case of low-voltage modulation, coherent detection is much less sensitive to modulator bias offset than delay interferometer-based demodulation.
基金supported by the National Basic Research Program of China(No.2010CB328300)the Fundamental Research Funds for the Central Universities(No.2009RC0314)+3 种基金the National Natural Science Foundation of China(Nos.61077050,61077014and60932004)the BUPT Young Foundation(No.2009CZ07)the Fundamental Research Funds for the Central Universitiesthe Open Foundation of State Key Laboratory of Optical Communication Technologies and Networks(WRI)(No.2010OCTN-02)
文摘We propose the single feeder fiber architecture for wavelength division multiplexing passive optical network(WDM-PON)based on directly modulated chirp managed laser(CML).The downlink(DL)signal output from the laser is converted to return-to-zero(RZ)differential phase shift signal using a pulse carver.The downstream signal is reused as a carrier for the upstream using intensity modulation technique.Simulation results show the error-free performance at symmetric data rate of 10 Gbit/s per channel with negligible power penalty and improved receiver sensitivity for the uplink(UL),over 25 km standard single-mode fiber(SSMF).A low-cost and reduced circuitry network design is implemented on a single feeder fiber with the elimination of differential encoder and one external modulator.
基金supported by the National Natural Science Foundation of China(Nos.61205068 and 61475133)the Hebei Province Science and Technology Support Program(Nos.15273304D and 14273301D)+1 种基金the College Youth Talent Project of Hebei Province(No.BJ2014057)the“Xin Rui Gong Cheng”Talent Project and the Excellent Youth Funds for School of Information Science and Engineering in Yanshan University(No.2014201)
文摘In this paper,a novel refractive index(RI) sensor is proposed based on the fused tapered special multi-mode fiber(SMMF).Firstly,a section of SMMF is spliced between two single-mode fibers(SMFs).Then,the SMMF is processed by a fused tapering machine,and a tapered fiber structure is fabricated.Finally,a fused tapered SMMF sensor is obtained for measuring external RI.The RI sensing mechanism of tapered SMMF sensor is analyzed in detail.For different fused tapering lengths,the experimental results show that the RI sensitivity can be up to 444.517 81 nm/RIU in the RI range of 1.334 9—1.347 0.The RI sensitivity is increased with the increase of fused tapering length.Moreover,it has many advantages,including high sensitivity,compact structure,fast response and wide application range.So it can be used to measure the solution concentration in the fields of biochemistry,health care and food processing.
基金supported by the National "973" Program of China (Nos. 2010CB328204 and 2010CB328205)the Nature Natural Science Foundation of China (Nos.61007041,61090393,and 60825103)+1 种基金the National 863 Program of Chinathe Program of Shanghai Subject Chief Scientist (No. 09XD1402200)
文摘We propose a stable multi-longitudinal Brillouin/semiconductor fiber laser (BSFL) as the upstream source in a bidirectional single-fiber wavelength-division multiplexing-passive optical network (WDM-PON). The downstream wavelength serves as the pump of the BSFL. Brillouin-frequency-shifted (-10.8 GHz) upstream carrier is generated to suppress the Rayleigh backscattering and back reflection-induced crosstalk. The stable multi-longitudinal operation of the BSFL, attributed to the four-wave mixing (FWM) effect in the semiconductor optical amplifier (SOA) reduces the difficulty of generating a stable single-longitudinal fiber laser-based upstream carrier. Bidirectional symmetric transmission at 10 Gb/s over a 12.5-km single mode fiber with less than 2-dB power penalty is demonstrated.