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
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
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
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
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.
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
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
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
A new method to obtain linear polarization operation by Brewster's angle-polished fiber end is demonstrated. By using the special polarization operation technique together with introducing a narrow-linewidth fiber gr...A new method to obtain linear polarization operation by Brewster's angle-polished fiber end is demonstrated. By using the special polarization operation technique together with introducing a narrow-linewidth fiber grating into the laser cavity, a cladding-pumped linear polarization and single-transverse-mode (M2 〈 1.1) Yb-doped fiber laser with narrow linewidth whose full-width at half-maximm (FWHM) is less than 0.2 nm, is obtained in a simple configuration. The output power is up to 10 W which is continuous- wave output at 1085 nm, and the slope efficiency is 63% with respect to the coupled pump power and 75% with respect to the absorbed pump power, respectively. The measured 21-dB polarization extinction ratio does not degrade with the output power. The simplicity of such an approach is highly beneficial for a number of applications, including the use of a fiber laser for the nonlinear wavelength conversion (especially for the intracavity frequency doubling) and for the coherent and spectral beam combination.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
A micro Fabry-Perot interferometer (M-FPI) is constructed by splicing a short section of polarization- maintaining photonic crystal fiber (PM-PCF) to an end-cleaved single-mode fiber with controllable offset. Due ...A micro Fabry-Perot interferometer (M-FPI) is constructed by splicing a short section of polarization- maintaining photonic crystal fiber (PM-PCF) to an end-cleaved single-mode fiber with controllable offset. Due to the high effective optical path difference induced by the solid core of the PCF, the M-FPI has an ultrasmall cavity of approximately 110 μm. The temperature sensitivity within a range from 33 ℃ to approximately 600 ℃ is measured to be 13.8 pm/℃, which shows good agreement with the theoretical result. This proposed sensor has the advantages of ultracompact size and high stability. Therefore, it is suitable for various space-limited sensing applications in harsh environments.展开更多
A compact fiber optic accelerometer based on a Michelson interferometer is proposed and demonstrated. In the proposed system, the sensing element consists of two single-mode fibers glued together by epoxy, which then ...A compact fiber optic accelerometer based on a Michelson interferometer is proposed and demonstrated. In the proposed system, the sensing element consists of two single-mode fibers glued together by epoxy, which then act as a simple supported beam. By demodulating the optical phase shift, the acceleration is determined as proportional to the force applied on the central position of the two single-mode fibers. This simple model is able to calculate the sensitivity and the resonant frequency of the compact accelerometer. The experimental results show that the sensitivity and the resonant frequency of the accelerometer are 0.42 rad/g and 600 Hz, respectively.展开更多
A simple fiber tip sensor for refractive index (RI) measurement based on Fabry-Perot (FP) interference modulated by Fresnel reflection is proposed and demonstrated. The sensor head consists of an etching- induced ...A simple fiber tip sensor for refractive index (RI) measurement based on Fabry-Perot (FP) interference modulated by Fresnel reflection is proposed and demonstrated. The sensor head consists of an etching- induced micro air gap near the tip of a single-mode fiber. The microgap and the fiber tip function as two reflectors to form a FP cavity. The external RI can be unambiguously measured by monitoring the fringe contrast of the interference pattern from the reflection spectrum. The experimental results show that the proposed sensor achieves temperature-independent RI measurement with good linear response. The proposed sensor achieves a high RI resolution of up to 3.4× 10^-5 and has advantages of low cost and easy fabrication.展开更多
A novel coherent Doppler lidar (CDL) system based on single-mode fiber (SMF) components and instruments is presented to measure the speed of target. A fiber interferometer used in CDL system is reported. This fibe...A novel coherent Doppler lidar (CDL) system based on single-mode fiber (SMF) components and instruments is presented to measure the speed of target. A fiber interferometer used in CDL system is reported. This fiber mixer is employed as a coherent receiver to resolve the shifts of signal-to-noise ratio (SNR) and mixing efficiency induced by backscattered field's wavefront error. For a certain wavelength, the maximum coupling efficiency between signal and SMF is determined by the ratio of pupil diameter to focal length of the coupling lens. The legible interference patterns and spectrum signals show that fiber interferometer is suitable to compensate for amplitude and phase vibrations. This robust coherent receiver can achieve improved CDL system performance with less transmitter power.展开更多
A high-efficiency Brillouin fiber ring laser is demonstrated using the standard single-mode fiber. The laser exhibits a 3.6-mW threshold. The output power is 22 mW with 40-mW pump power, and the maximum optical-to-opt...A high-efficiency Brillouin fiber ring laser is demonstrated using the standard single-mode fiber. The laser exhibits a 3.6-mW threshold. The output power is 22 mW with 40-mW pump power, and the maximum optical-to-optical efficiency is 5570. The output is single wavelength with a 3-dB linewidth of 5 MHz, and the interval of center frequency between the laser and the pump light is 11 GHz (0.088 nm). It is shown that the stimulated Brillouin scattering threshold of ring resonator is lower and the energy transfer efficiency is higher than those in fiber.展开更多
The Raman gain coefficients in polarization maintaining photonic crystal fibers (PM-PCFs) are analyzedin in order to design fibers for linearly polarized Raman fiber laser with enhanced performances. The results sho...The Raman gain coefficients in polarization maintaining photonic crystal fibers (PM-PCFs) are analyzedin in order to design fibers for linearly polarized Raman fiber laser with enhanced performances. The results show that a well designed germanium-doped PM-PCF can attain the value of Raman gain coefficient over 50 W^-1·km^-1, going with very high birefringence and single mode operation at 1.55-μm signal wavelengthand 1.45-μm pump wavelength.展开更多
The visibility in magnetostrictive fiber-optic interferometric sensors using a Gaussian laser beam is analyzed. It is shown that the conventional Gaussian laser beam has little influence on the visibility. The visibil...The visibility in magnetostrictive fiber-optic interferometric sensors using a Gaussian laser beam is analyzed. It is shown that the conventional Gaussian laser beam has little influence on the visibility. The visibility depends strongly on the input state of polarization (SOP). We implement a cylindrical transducer and build a measurement setup with a polarization controller. The visibility dependent on the SOP of input light is measured. The estimated values are similar to the experiment results, which verifies the analysis.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℃.
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.
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.
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.
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.
基金supported by the National High Technology Research and Development Program of China (No.2008AA03Z405)the Shanghai Natural Science Foundation(No.10ZR1433600).
文摘A new method to obtain linear polarization operation by Brewster's angle-polished fiber end is demonstrated. By using the special polarization operation technique together with introducing a narrow-linewidth fiber grating into the laser cavity, a cladding-pumped linear polarization and single-transverse-mode (M2 〈 1.1) Yb-doped fiber laser with narrow linewidth whose full-width at half-maximm (FWHM) is less than 0.2 nm, is obtained in a simple configuration. The output power is up to 10 W which is continuous- wave output at 1085 nm, and the slope efficiency is 63% with respect to the coupled pump power and 75% with respect to the absorbed pump power, respectively. The measured 21-dB polarization extinction ratio does not degrade with the output power. The simplicity of such an approach is highly beneficial for a number of applications, including the use of a fiber laser for the nonlinear wavelength conversion (especially for the intracavity frequency doubling) and for the coherent and spectral beam combination.
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 Natural Science Foundation of China(Nos.61077006,60727004,and 61077060)the National "863" Program of China(Nos. 2007AA03Z413 and 2009AA06Z203)+3 种基金the Ministry of Education Project of Science and Technology Innovation (No.Z08119)the Ministry of Science and Technology Project of International Cooperation(No.2008CR1063)Shaanxi Province Project of Science and Technology Innovation (Nos.2009ZKC01-19 and 2008ZDGC-14)Northwestern University Teaching and Research Project (Nos.YC07059 and KJG10036)
文摘A micro Fabry-Perot interferometer (M-FPI) is constructed by splicing a short section of polarization- maintaining photonic crystal fiber (PM-PCF) to an end-cleaved single-mode fiber with controllable offset. Due to the high effective optical path difference induced by the solid core of the PCF, the M-FPI has an ultrasmall cavity of approximately 110 μm. The temperature sensitivity within a range from 33 ℃ to approximately 600 ℃ is measured to be 13.8 pm/℃, which shows good agreement with the theoretical result. This proposed sensor has the advantages of ultracompact size and high stability. Therefore, it is suitable for various space-limited sensing applications in harsh environments.
基金partially supported by the National Nature Science Foundation of China (Nos.60877046,60707013,60807032,and 60927008)the Key Project of the Nature Science Foundation of Heilongjiang Province(No.ZD200810)the Fundamental Research Funds for the Central Universities (No.HEUCFZ1020)
文摘A compact fiber optic accelerometer based on a Michelson interferometer is proposed and demonstrated. In the proposed system, the sensing element consists of two single-mode fibers glued together by epoxy, which then act as a simple supported beam. By demodulating the optical phase shift, the acceleration is determined as proportional to the force applied on the central position of the two single-mode fibers. This simple model is able to calculate the sensitivity and the resonant frequency of the compact accelerometer. The experimental results show that the sensitivity and the resonant frequency of the accelerometer are 0.42 rad/g and 600 Hz, respectively.
基金supported by the National Natural Science Foundation of China (Nos. 60727004 and 61077060)the National "863" Program of China (Nos.2007AA03Z413 and 2009AA06Z203)+4 种基金the Ministry of Education Project of Science and Technology Innovation(No. Z08119)the Ministry of Science and Technology Project of International Cooperation (No. 2008CR1063)the Shaanxi Province Project of Science and Technology Innovation (Nos. 2009ZKC01-19 and 2008ZDGC-14)the Guangdong Nature Science Foundation (No.S2011010001631)the Fundamental Research Funds for the Central Universities of China (No. 11611601)
文摘A simple fiber tip sensor for refractive index (RI) measurement based on Fabry-Perot (FP) interference modulated by Fresnel reflection is proposed and demonstrated. The sensor head consists of an etching- induced micro air gap near the tip of a single-mode fiber. The microgap and the fiber tip function as two reflectors to form a FP cavity. The external RI can be unambiguously measured by monitoring the fringe contrast of the interference pattern from the reflection spectrum. The experimental results show that the proposed sensor achieves temperature-independent RI measurement with good linear response. The proposed sensor achieves a high RI resolution of up to 3.4× 10^-5 and has advantages of low cost and easy fabrication.
文摘A novel coherent Doppler lidar (CDL) system based on single-mode fiber (SMF) components and instruments is presented to measure the speed of target. A fiber interferometer used in CDL system is reported. This fiber mixer is employed as a coherent receiver to resolve the shifts of signal-to-noise ratio (SNR) and mixing efficiency induced by backscattered field's wavefront error. For a certain wavelength, the maximum coupling efficiency between signal and SMF is determined by the ratio of pupil diameter to focal length of the coupling lens. The legible interference patterns and spectrum signals show that fiber interferometer is suitable to compensate for amplitude and phase vibrations. This robust coherent receiver can achieve improved CDL system performance with less transmitter power.
文摘A high-efficiency Brillouin fiber ring laser is demonstrated using the standard single-mode fiber. The laser exhibits a 3.6-mW threshold. The output power is 22 mW with 40-mW pump power, and the maximum optical-to-optical efficiency is 5570. The output is single wavelength with a 3-dB linewidth of 5 MHz, and the interval of center frequency between the laser and the pump light is 11 GHz (0.088 nm). It is shown that the stimulated Brillouin scattering threshold of ring resonator is lower and the energy transfer efficiency is higher than those in fiber.
基金This work was supported by the National "863" Program of China (No. 2004AA31G200) and the Foundation of Beijing Jiaotong University. H. Fang's e-mail address
文摘The Raman gain coefficients in polarization maintaining photonic crystal fibers (PM-PCFs) are analyzedin in order to design fibers for linearly polarized Raman fiber laser with enhanced performances. The results show that a well designed germanium-doped PM-PCF can attain the value of Raman gain coefficient over 50 W^-1·km^-1, going with very high birefringence and single mode operation at 1.55-μm signal wavelengthand 1.45-μm pump wavelength.
基金This work was supported by the National Natural Science Foundation of China(No. 90204006 and 60377013)the Ministry of Education, China (No. 20030248035)the Science and Technology Committee of Shanghai Municipality (No. 036105009)
文摘The visibility in magnetostrictive fiber-optic interferometric sensors using a Gaussian laser beam is analyzed. It is shown that the conventional Gaussian laser beam has little influence on the visibility. The visibility depends strongly on the input state of polarization (SOP). We implement a cylindrical transducer and build a measurement setup with a polarization controller. The visibility dependent on the SOP of input light is measured. The estimated values are similar to the experiment results, which verifies the analysis.