Many delayed-choice experiments based on Mach-Zehnder interferometers (MZI) have been considered and made to address the fundamental problem of wave-particle duality. Conventional wisdom long holds that by inserting...Many delayed-choice experiments based on Mach-Zehnder interferometers (MZI) have been considered and made to address the fundamental problem of wave-particle duality. Conventional wisdom long holds that by inserting or removing the second beam splitter (BS2) in a controllable way, microscopic particles (photons, electrons, etc.) transporting within the MZI can lie in the quantum superposition of the wave and particle state as ψ= aw ψ wave + ap ψ particle. Here we present an alternative interpretation to these delayed-choice experiments. We notice that as the BS2 is purely classical, the inserting and removing operation of the BS2 imposes a time- modulated Hamiltonian H mod (t) = a(t)Hin + b(t)Hout, instead of a quantum superposition of H in and Hour as H = awHin + apHout, to act upon the incident wave function. Solution of this quantum scattering problem, rather than the long held quantum eigen-problem yields a synchronically time-modulated output wave function as ψ mod (t) = a(t) ψ wave +b(t) ψ particle, instead of the stationary quantum superposition state ψ = aw ψ wave + ap ψ particle. As a result, the probability of particle output from the MZI behaves as if they are in the superposition of the wave and particle state when many events over time accumulation are counted and averaged. We expect that these elementary but insightful analyses will shed a new light on exploring basic physics beyond the long-held wisdom of wave-particle duality and the principle of complementarity.展开更多
A distributed optical fiber disturbance detection system consisted of a Sagnac interferometer and a Mach-Zehnder interferometer is demonstrated. Two interferometers outputs are connected to an electric band-pass filte...A distributed optical fiber disturbance detection system consisted of a Sagnac interferometer and a Mach-Zehnder interferometer is demonstrated. Two interferometers outputs are connected to an electric band-pass filter via a detector respectively. The central frequencies of the two filters are selected adaptively according to the disturbance frequency. The disturbance frequency is obtained by either frequency spectrum of the two interferometers outputs. An alarm is given out only when the Sagnac interferometer output is changed. A disturbance position is determined by calculating a time difference with a cross-correlation method between the filter output connected to the Sagnac interferometer and derivative of the filter output connected to the Mach-Zehnder interferometer. The frequency spectrum, derivative and cross-correlation are obtained by a signal processing system. Theory analysis and simulation results are presented. They show that the system structure and location method are effective, accurate, and immune to environmental variations.展开更多
An in-fiber Mach-Zehnder interferometer for strain measurement is proposed and experimentally demonstrated. The sensor consists of a taper followed by a short section of a multi-mode fiber (MMF) and a dispersion com...An in-fiber Mach-Zehnder interferometer for strain measurement is proposed and experimentally demonstrated. The sensor consists of a taper followed by a short section of a multi-mode fiber (MMF) and a dispersion com- pensating fiber (DCF), which is sandwiched between two single mode fibers (SMFs). The taper is used as a fiber coupler to excite cladding modes in the SMF, and these cladding modes transmit within the MMF and the DCF. The core mode and the cladding modes interfere in the DCF SMF fusion point to form intermodal interference. A well-defined interference spectrum is obtained in the experiment. Selected interference dips are used to measure the strain changes. The experimental results show that this device is sensitive to strain with the wavelength-referenced sensitivity of 2.6 pm/με and the power-referenced sensitivity of 0. 0027 dB/με, respectively.展开更多
The temperature-induced complex refractive index(CRI) effect of graphene is demonstrated theoretically and experimentally based on a graphene coated in-fiber MZI(Mach-Zehnder interferometer). The relationships bet...The temperature-induced complex refractive index(CRI) effect of graphene is demonstrated theoretically and experimentally based on a graphene coated in-fiber MZI(Mach-Zehnder interferometer). The relationships between real and imaginary parts of the graphene CRI and temperature are obtained through investigating the dip wavelength and intensity of the MZI interference spectrum changing with temperature, respectively. The temperature effect of CRI of the graphene is also analyzed theoretically. Both experimental and theoretical studies show that the real part and imaginary part of the CRI nonlinearly decrease and increase with temperature increasing, respectively. This graphene-coated in-fiber MZI structure also possesses the advantages of easy fabrication, miniaturization, low cost and robustness. It has potential applications in nanomaterial-based optic devices for communication and sensing.展开更多
We argue that the modification proposed by Li et al. [Chin. Phys. Lett. 32 (2015)050303] to the experiment of Danan et al. [Phys. Rev. Lett. 111 (2013) 240402] does not test the past of the photon as characterized...We argue that the modification proposed by Li et al. [Chin. Phys. Lett. 32 (2015)050303] to the experiment of Danan et al. [Phys. Rev. Lett. 111 (2013) 240402] does not test the past of the photon as characterized by local weak traces. Instead of answering the questions: (i) were the photons in A? (ii) were the photons in B? and (iii) were the photons in C? the proposed experiment measures a degenerate operator answering the questions: (i) were the photons in A? and (ii) were the photons in B and C together? A negative answer to the last question does not tell us if photons were present in B or C. On the other hand, a simple variation of the proposal by Li et al. does provide conceptually better evidence for the past of the pre- and post-selected photon, but this evidence will be in agreement with the results of Danan et al.展开更多
On the silicon-on-insulator platform, an ultra compact temperature-insensitive modulator based on a cascaded microring assistant Mach-Zehnder interferometer is proposed and demonstrated with numerical simulation. Acco...On the silicon-on-insulator platform, an ultra compact temperature-insensitive modulator based on a cascaded microring assistant Mach-Zehnder interferometer is proposed and demonstrated with numerical simulation. According to the calculated results, the tolerated variation of ambient temperature can be as high as 134 ℃ while the footprint of such a silicon modulator is only 340 μm2.展开更多
An ideal experiment is designed to determine the past of a particle in the nested Mach-Zehnder interferometer (MZI) by using standard quantum mechanics with quantum non-demolition measurements. We find that when the...An ideal experiment is designed to determine the past of a particle in the nested Mach-Zehnder interferometer (MZI) by using standard quantum mechanics with quantum non-demolition measurements. We find that when the photon reaches the detector, it only follows one arm of the outer interferometer and leaves no trace in the inner MZI. When it goes through the inner MZI, it cannot reach the detector. Our result obtained from the standard quantum mechanics contradicts the statement based on two-state vector formulism, 'the photon did not enter the (inner) interferometer, the photon never left the interferometer, but it was there'. Therefore, the statement and also the overlapping claim are incorrect.展开更多
We present a two-photon interference experiment in a modified Mach-Zehnder (MZ) interferometer in which two Hong-Ou-Mandel effects occur in tandem and construct superposed two-photon states. The signal photons pass ...We present a two-photon interference experiment in a modified Mach-Zehnder (MZ) interferometer in which two Hong-Ou-Mandel effects occur in tandem and construct superposed two-photon states. The signal photons pass both the arms of the MZ interferometer while the idler photons pass one arm only. Interestingly, the probability of the idler photons emerging from any output port still shows a sine oscillation with the two-photon phase difference and it can be characterized only by the indistinguishability of the two-photon amplitudes. We also observe a two-photon interference pattern with a period being equal to the wavelength of the parametric photons instead of the two-photon photonie de Broglie wavelength due to the presence of two-photon phase difference, in particular, with complementary probabilities of finding the two-photon pairs in two output ports. The abundant observations can facilitate a more comprehensive understanding of the two-photon interference.展开更多
This study focuses on the experimental measurements of the heat transfer coefficient over a flat plate with a 30° leading edge. Under forced convection by a hot/cold air and flow over a cooled/heated flat plate, ...This study focuses on the experimental measurements of the heat transfer coefficient over a flat plate with a 30° leading edge. Under forced convection by a hot/cold air and flow over a cooled/heated flat plate, the thermal boundary layer and its thickness are quantitatively visualized and measured using a Mach-Zehnder interferometer. In addition, the variation in the local heat transfer coefficient is evaluated experimentally with respect to the air flow velocity and temperature. Differences within the heat transfer performance between the plates are confirmed and discussed. As a result, the average heat transfer performance is about the same for the heated plate and the cooled plate under all air velocity conditions. This contrasts with the theoretical prediction in the case of low air velocity, the reason considered was that the buoyancy at the 30° leading edge blocked air from flowing across the surface of the plate.展开更多
Fiber optic Mach Zehnder interferometer(MZI) can be used as wavelength multiplexers and demultiplexers. The △ L and △ directly influence the properties of MZI. To lengthen the △ L can demultiplex much more wavelen...Fiber optic Mach Zehnder interferometer(MZI) can be used as wavelength multiplexers and demultiplexers. The △ L and △ directly influence the properties of MZI. To lengthen the △ L can demultiplex much more wavelengths, but when the △ L is longer, the temperature will influence MZI more seriously. A method to solve this problem is proposed, which enables MZI to work stably. The wavelength distance is 0.8 nm, and the extinction ratio is high.展开更多
In order to improve the multiplexing capability of the optical sensors based on the lower interferential optic fiber sensing technology and the white light fiber-optic Mach-Zehnder interferometer,reflective ladder top...In order to improve the multiplexing capability of the optical sensors based on the lower interferential optic fiber sensing technology and the white light fiber-optic Mach-Zehnder interferometer,reflective ladder topology network ( RLT) with tailored formula was proposed. The topology network consists of 6 rungs sensing elements linked by 5 couplers. Two cases with different choices of couplers were contrasted: one is equal coupling ratio,and the other is tailored coupling ratio. Through the simulation of these two cases,the detailed multiplexing capability was analyzed,and accordingly the experiments were also carried out. The simulation results showed that,the tailored formula enhances the multiplexing capability of the structure. In the first case, the maximum number of sensors which can be multiplexed is 8,and in the other case is 12 fiber optic sensors. The experimental results have a good agreement with numerical simulation results. Thus,it is considered expedient to incorporate RLT into large-scale building,grounds,bridges,dams,tunnels,highways and perimeter security.展开更多
A novel Mach–Zehnder(M-Z)interferometer used to measure the dispersion and phase shift of a light beam is reported.The interferometer consists of two identical beam displacing polarizers,which makes two beams of inte...A novel Mach–Zehnder(M-Z)interferometer used to measure the dispersion and phase shift of a light beam is reported.The interferometer consists of two identical beam displacing polarizers,which makes two beams of interference light pass through the same optical device and greatly improves the stability of the M-Z interferometer.The basic method of dispersion and phase measuring through the present interferometer is introduced in detail,and the actual application is demonstrated by a specific example.Because the measuring of dispersion and phase shift is the heating point in the field of optics,it is obvious that the M-Z interferometer will have important applications in aspects of optics,especially quantum optics and optical information processing.展开更多
A novel 2×2 wavelength selective cross-connect (WSXC) module, which is composed of a Bragg-grating-based Mach- Zehnder interferometer (MZI), a pair of optical waveguides, a pair of 1×2 optical switches (OSWs...A novel 2×2 wavelength selective cross-connect (WSXC) module, which is composed of a Bragg-grating-based Mach- Zehnder interferometer (MZI), a pair of optical waveguides, a pair of 1×2 optical switches (OSWs) and a pair of Y-model combiners is proposed. The mathematical description of the proposed 2×2 WSXC module is given and explained. Multi- channel multi-wavelength selective cross-connect can be fabricated with the proposed 2×2 WSXC module, together with multistage interconnection networks (MINs). A four-wavelength 4×4 WSXC is demonstrated by simulation to validate the flexibility of the proposed WSXC.展开更多
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
The multilongitudinal mode[MLM]high-spectral-resolution lidar[HSRL]based on the Mach±Zehnder interferometer[MZI]is constructed in Xi’an for accurate measurements of aerosol optical properties.The critical requir...The multilongitudinal mode[MLM]high-spectral-resolution lidar[HSRL]based on the Mach±Zehnder interferometer[MZI]is constructed in Xi’an for accurate measurements of aerosol optical properties.The critical requirement of the optimal match between the free spectral range of MZI and the longitudinal mode interval of the MLM laser is influenced by the laboratory temperature,pressure,and vibration.To realize the optimal separation of aerosol Mie scattering signals and molecular Rayleigh scattering signals excited by the MLM laser,a self-tuning technique to dynamically adjust the optical path difference[OPD]of the MZI is proposed,which utilizes the maximum ratio between the received power of the Mie channel and Rayleigh channel as the criterion of the OPD displacement.The preliminary experiments show the feasibility of the MLM-HSRL with self-tuning MZI and the stable performance in the separation of aerosol Mie scattering signals and molecular Rayleigh scattering signals.展开更多
An all-fiber temperature and curvature sensor based on Mach-Zehnder interferometer(MZI)was proposed.The MZI was a sandwich structure which is composed of ring-core fiber(RCF),no-core fiber(NCF)and single-mode fiber(SM...An all-fiber temperature and curvature sensor based on Mach-Zehnder interferometer(MZI)was proposed.The MZI was a sandwich structure which is composed of ring-core fiber(RCF),no-core fiber(NCF)and single-mode fiber(SMF).The temperature and curvature can be demodulated by the wavelength shift and the intensity variation of the dips respectively in the transmission spectrum.The measurement results show that the sensitivity of curvature is−7.88 dBm/m^(−1)in the range from 3.0 m^(−1)to 4.2 m^(−1)and the sensitivity of temperature is 53.5 pm/°C in the range from 60°C to 200°C.In addition,the cascaded FBG in the proposed structure,also sensitive to temperature,was used to monitor the fluctuation of temperature.The compact structure,the real-time temperature and the high curvature sensitivity make the sensor have the potential in the field of construction health monitoring and mining safety production.展开更多
Wavelength-tunable dissipative solitons and amplifier similaritons have been obtained by inserting all-fiber Mach-Zehnder interferometer(MZI) filters with different free spectral ranges(FSRs) in a Yb-doped mode-locked...Wavelength-tunable dissipative solitons and amplifier similaritons have been obtained by inserting all-fiber Mach-Zehnder interferometer(MZI) filters with different free spectral ranges(FSRs) in a Yb-doped mode-locked fiber laser.The MZI filter is fabricated by splicing one segment of seven-core fiber(SCF) between two segments of single-mode fibers.The bandwidth of the filter depends on the FSR of the modulated interference curve and consequently depends on the tapered fiber diameter.Inserting MZI filters with bandwidths in a fiber laser and applying a tensile strain on the tapered SCF,both wavelengthtunable dissipative solitons and amplifier similaritons have been obtained.展开更多
A novel fiber inline Mach-Zehnder interferometer(MZI)is proposed for simultaneous measurement of curvature and temperature.The sensor composes of single mode-multimode-dispersion compensation-multimode-single mode fib...A novel fiber inline Mach-Zehnder interferometer(MZI)is proposed for simultaneous measurement of curvature and temperature.The sensor composes of single mode-multimode-dispersion compensation-multimode-single mode fiber(MMF-DCF-MMF)structure,using the direct fusion technology.The experimental results show curvature sensitivities of−12.82 nm/m^(−1) and−14.42 nm/m^(−1) in the range of 0−0.65 m^(−1) for two resonant dips,as well as temperature sensitivities of 57.6 pm/and 74.3℃pm/within the range of 20℃℃−150.In addition,℃the sensor has unique advantages of easy fabrication,low cost,high fringe visibility of 24 dB,and high sensitivity,which shows a good application prospect in dual-parameters of sensing of curvature and temperature.展开更多
A Mach-Zehnder interferometer(MZI)for high temperature(1000°C)sensing based on few mode fiber(FMF)was proposed and experimentally demonstrated.The sensor was fabricated by fusing a section of FMF between two sing...A Mach-Zehnder interferometer(MZI)for high temperature(1000°C)sensing based on few mode fiber(FMF)was proposed and experimentally demonstrated.The sensor was fabricated by fusing a section of FMF between two single-mode fibers(SMFs).The structure was proven to be an excellent high temperature sensor with good stability,repeatability,and high temperature sensitivity(48.2 pm/C)after annealing process at a high temperature lasting some hours,and a wide working temperature range(from room temperature to 1000 C).In addition,the simple fabrication process and the low cost offered a great potential for sensing in high temperature environments.展开更多
基金Supported by the National Basic Research Program of China under Grant No 2013CB632704the National Natural Science Foundation of China under Grant No 11434017
文摘Many delayed-choice experiments based on Mach-Zehnder interferometers (MZI) have been considered and made to address the fundamental problem of wave-particle duality. Conventional wisdom long holds that by inserting or removing the second beam splitter (BS2) in a controllable way, microscopic particles (photons, electrons, etc.) transporting within the MZI can lie in the quantum superposition of the wave and particle state as ψ= aw ψ wave + ap ψ particle. Here we present an alternative interpretation to these delayed-choice experiments. We notice that as the BS2 is purely classical, the inserting and removing operation of the BS2 imposes a time- modulated Hamiltonian H mod (t) = a(t)Hin + b(t)Hout, instead of a quantum superposition of H in and Hour as H = awHin + apHout, to act upon the incident wave function. Solution of this quantum scattering problem, rather than the long held quantum eigen-problem yields a synchronically time-modulated output wave function as ψ mod (t) = a(t) ψ wave +b(t) ψ particle, instead of the stationary quantum superposition state ψ = aw ψ wave + ap ψ particle. As a result, the probability of particle output from the MZI behaves as if they are in the superposition of the wave and particle state when many events over time accumulation are counted and averaged. We expect that these elementary but insightful analyses will shed a new light on exploring basic physics beyond the long-held wisdom of wave-particle duality and the principle of complementarity.
基金Project supported by the Innovation Program of Education Commission of Shanghai Municipality (Grant No.10YZ19)the Shanghai Leading Academic Discipline Project (Grant No.S30108)the Shanghai Key Laboratory of Specialty Fiber Optics and Optical Access Networks (Grant No.SKLSFO200903)
文摘A distributed optical fiber disturbance detection system consisted of a Sagnac interferometer and a Mach-Zehnder interferometer is demonstrated. Two interferometers outputs are connected to an electric band-pass filter via a detector respectively. The central frequencies of the two filters are selected adaptively according to the disturbance frequency. The disturbance frequency is obtained by either frequency spectrum of the two interferometers outputs. An alarm is given out only when the Sagnac interferometer output is changed. A disturbance position is determined by calculating a time difference with a cross-correlation method between the filter output connected to the Sagnac interferometer and derivative of the filter output connected to the Mach-Zehnder interferometer. The frequency spectrum, derivative and cross-correlation are obtained by a signal processing system. Theory analysis and simulation results are presented. They show that the system structure and location method are effective, accurate, and immune to environmental variations.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61077006,60727004,and 61077060the China National Petroleum Corporation Science and Technology Development Projects under Grant No 2014B-4012the Science Research Plan Projects of Shaanxi Education Department under Grant No 14JK1580
文摘An in-fiber Mach-Zehnder interferometer for strain measurement is proposed and experimentally demonstrated. The sensor consists of a taper followed by a short section of a multi-mode fiber (MMF) and a dispersion com- pensating fiber (DCF), which is sandwiched between two single mode fibers (SMFs). The taper is used as a fiber coupler to excite cladding modes in the SMF, and these cladding modes transmit within the MMF and the DCF. The core mode and the cladding modes interfere in the DCF SMF fusion point to form intermodal interference. A well-defined interference spectrum is obtained in the experiment. Selected interference dips are used to measure the strain changes. The experimental results show that this device is sensitive to strain with the wavelength-referenced sensitivity of 2.6 pm/με and the power-referenced sensitivity of 0. 0027 dB/με, respectively.
基金Project supported by the Shandong Provincial Natural Science Foundation of China(Grant Nos.ZR2009AM017 and ZR2013FM019)the National Postdoctoral Project of China(Grant Nos.200902574 and 20080441150)+2 种基金the Shandong Provincial Education Department Foundation of China(Grant No.J06P14)the Opening Foundation of State Key Lab of Minning Disaster Prevention and Control Co-founded by Shandong Provincethe Ministry of Science and Technology of China(Grant No.MDPC201602)
文摘The temperature-induced complex refractive index(CRI) effect of graphene is demonstrated theoretically and experimentally based on a graphene coated in-fiber MZI(Mach-Zehnder interferometer). The relationships between real and imaginary parts of the graphene CRI and temperature are obtained through investigating the dip wavelength and intensity of the MZI interference spectrum changing with temperature, respectively. The temperature effect of CRI of the graphene is also analyzed theoretically. Both experimental and theoretical studies show that the real part and imaginary part of the CRI nonlinearly decrease and increase with temperature increasing, respectively. This graphene-coated in-fiber MZI structure also possesses the advantages of easy fabrication, miniaturization, low cost and robustness. It has potential applications in nanomaterial-based optic devices for communication and sensing.
基金Supported by the German-Israeli Foundation for Scientific Research and Development under Grant No I-1275-303.14
文摘We argue that the modification proposed by Li et al. [Chin. Phys. Lett. 32 (2015)050303] to the experiment of Danan et al. [Phys. Rev. Lett. 111 (2013) 240402] does not test the past of the photon as characterized by local weak traces. Instead of answering the questions: (i) were the photons in A? (ii) were the photons in B? and (iii) were the photons in C? the proposed experiment measures a degenerate operator answering the questions: (i) were the photons in A? and (ii) were the photons in B and C together? A negative answer to the last question does not tell us if photons were present in B or C. On the other hand, a simple variation of the proposal by Li et al. does provide conceptually better evidence for the past of the pre- and post-selected photon, but this evidence will be in agreement with the results of Danan et al.
基金Project supported by the National Basic Research Program of China(Grant Nos.2011CBA00608,2011CBA00303,2011CB301803, and 2010CB327405)the National Natural Science Foundation of China(Grant Nos.61036011 and 61036010)the Project of Science and Technology from the Communication Information Security Control Laboratory
文摘On the silicon-on-insulator platform, an ultra compact temperature-insensitive modulator based on a cascaded microring assistant Mach-Zehnder interferometer is proposed and demonstrated with numerical simulation. According to the calculated results, the tolerated variation of ambient temperature can be as high as 134 ℃ while the footprint of such a silicon modulator is only 340 μm2.
基金Supported by the National Basic Research Program of China under Grant Nos 2011CB922203 and 2012CB921603the National Natural Science Foundation of China under Grant Nos 1174026 and U1330203
文摘An ideal experiment is designed to determine the past of a particle in the nested Mach-Zehnder interferometer (MZI) by using standard quantum mechanics with quantum non-demolition measurements. We find that when the photon reaches the detector, it only follows one arm of the outer interferometer and leaves no trace in the inner MZI. When it goes through the inner MZI, it cannot reach the detector. Our result obtained from the standard quantum mechanics contradicts the statement based on two-state vector formulism, 'the photon did not enter the (inner) interferometer, the photon never left the interferometer, but it was there'. Therefore, the statement and also the overlapping claim are incorrect.
基金Supported by the National Key R&D Program of China under Grant Nos 2017YFA0303800 and 2017YFA0303700the National Natural Science Foundation of China under Grant Nos 11534006,11774183 and 11674184+1 种基金the Natural Science Foundation of Tianjin under Grant No 16JCZDJC31300the Collaborative Innovation Center of Extreme Optics
文摘We present a two-photon interference experiment in a modified Mach-Zehnder (MZ) interferometer in which two Hong-Ou-Mandel effects occur in tandem and construct superposed two-photon states. The signal photons pass both the arms of the MZ interferometer while the idler photons pass one arm only. Interestingly, the probability of the idler photons emerging from any output port still shows a sine oscillation with the two-photon phase difference and it can be characterized only by the indistinguishability of the two-photon amplitudes. We also observe a two-photon interference pattern with a period being equal to the wavelength of the parametric photons instead of the two-photon photonie de Broglie wavelength due to the presence of two-photon phase difference, in particular, with complementary probabilities of finding the two-photon pairs in two output ports. The abundant observations can facilitate a more comprehensive understanding of the two-photon interference.
文摘This study focuses on the experimental measurements of the heat transfer coefficient over a flat plate with a 30° leading edge. Under forced convection by a hot/cold air and flow over a cooled/heated flat plate, the thermal boundary layer and its thickness are quantitatively visualized and measured using a Mach-Zehnder interferometer. In addition, the variation in the local heat transfer coefficient is evaluated experimentally with respect to the air flow velocity and temperature. Differences within the heat transfer performance between the plates are confirmed and discussed. As a result, the average heat transfer performance is about the same for the heated plate and the cooled plate under all air velocity conditions. This contrasts with the theoretical prediction in the case of low air velocity, the reason considered was that the buoyancy at the 30° leading edge blocked air from flowing across the surface of the plate.
文摘Fiber optic Mach Zehnder interferometer(MZI) can be used as wavelength multiplexers and demultiplexers. The △ L and △ directly influence the properties of MZI. To lengthen the △ L can demultiplex much more wavelengths, but when the △ L is longer, the temperature will influence MZI more seriously. A method to solve this problem is proposed, which enables MZI to work stably. The wavelength distance is 0.8 nm, and the extinction ratio is high.
基金Sponsored by the Natural Science Foundation of Heilongjiang Province (Grant No. QC2012C081)the Creative Qualified Scientists and Technicians Foundation of Harbin City (Grant No. RC2012QN001025)the National Natural Science Foundation of China (Grant No. 61107069 and 41174161)
文摘In order to improve the multiplexing capability of the optical sensors based on the lower interferential optic fiber sensing technology and the white light fiber-optic Mach-Zehnder interferometer,reflective ladder topology network ( RLT) with tailored formula was proposed. The topology network consists of 6 rungs sensing elements linked by 5 couplers. Two cases with different choices of couplers were contrasted: one is equal coupling ratio,and the other is tailored coupling ratio. Through the simulation of these two cases,the detailed multiplexing capability was analyzed,and accordingly the experiments were also carried out. The simulation results showed that,the tailored formula enhances the multiplexing capability of the structure. In the first case, the maximum number of sensors which can be multiplexed is 8,and in the other case is 12 fiber optic sensors. The experimental results have a good agreement with numerical simulation results. Thus,it is considered expedient to incorporate RLT into large-scale building,grounds,bridges,dams,tunnels,highways and perimeter security.
基金the National Natural Science Foundation of China(No 61178067)the Doctoral Starting-up Foundation of Taiyuan University of Science and Technology(No 20102003).
文摘A novel Mach–Zehnder(M-Z)interferometer used to measure the dispersion and phase shift of a light beam is reported.The interferometer consists of two identical beam displacing polarizers,which makes two beams of interference light pass through the same optical device and greatly improves the stability of the M-Z interferometer.The basic method of dispersion and phase measuring through the present interferometer is introduced in detail,and the actual application is demonstrated by a specific example.Because the measuring of dispersion and phase shift is the heating point in the field of optics,it is obvious that the M-Z interferometer will have important applications in aspects of optics,especially quantum optics and optical information processing.
基金This work has been supported in part by the Natural Science Fou- ndation of China (No.60677023)by Hi-Tech Research andDevelopment Program of China (No. 2006AA01Z240).
文摘A novel 2×2 wavelength selective cross-connect (WSXC) module, which is composed of a Bragg-grating-based Mach- Zehnder interferometer (MZI), a pair of optical waveguides, a pair of 1×2 optical switches (OSWs) and a pair of Y-model combiners is proposed. The mathematical description of the proposed 2×2 WSXC module is given and explained. Multi- channel multi-wavelength selective cross-connect can be fabricated with the proposed 2×2 WSXC module, together with multistage interconnection networks (MINs). A four-wavelength 4×4 WSXC is demonstrated by simulation to validate the flexibility of the proposed WSXC.
基金Supported by the National Natural Science Foundation of China (No.10174057, 90201011) and the Key Project of Chinese Ministry of Education (No.105148).
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supported by the National Natural Science Foundation of China(Nos.42175149 and 41775035)the China-CEEC Joint Higher Education Project(No.202017)the Natural Science Foundation of Shaanxi Province,China(No.2020JM-445)。
文摘The multilongitudinal mode[MLM]high-spectral-resolution lidar[HSRL]based on the Mach±Zehnder interferometer[MZI]is constructed in Xi’an for accurate measurements of aerosol optical properties.The critical requirement of the optimal match between the free spectral range of MZI and the longitudinal mode interval of the MLM laser is influenced by the laboratory temperature,pressure,and vibration.To realize the optimal separation of aerosol Mie scattering signals and molecular Rayleigh scattering signals excited by the MLM laser,a self-tuning technique to dynamically adjust the optical path difference[OPD]of the MZI is proposed,which utilizes the maximum ratio between the received power of the Mie channel and Rayleigh channel as the criterion of the OPD displacement.The preliminary experiments show the feasibility of the MLM-HSRL with self-tuning MZI and the stable performance in the separation of aerosol Mie scattering signals and molecular Rayleigh scattering signals.
基金supported by the National Natural Science Foundation of China (No.62175055)the Natural Science Foundation of Handan University (No.XZ2022408)
文摘An all-fiber temperature and curvature sensor based on Mach-Zehnder interferometer(MZI)was proposed.The MZI was a sandwich structure which is composed of ring-core fiber(RCF),no-core fiber(NCF)and single-mode fiber(SMF).The temperature and curvature can be demodulated by the wavelength shift and the intensity variation of the dips respectively in the transmission spectrum.The measurement results show that the sensitivity of curvature is−7.88 dBm/m^(−1)in the range from 3.0 m^(−1)to 4.2 m^(−1)and the sensitivity of temperature is 53.5 pm/°C in the range from 60°C to 200°C.In addition,the cascaded FBG in the proposed structure,also sensitive to temperature,was used to monitor the fluctuation of temperature.The compact structure,the real-time temperature and the high curvature sensitivity make the sensor have the potential in the field of construction health monitoring and mining safety production.
基金supported in part by the National Natural Science Foundation of China(No.61875247)the Natural Science Foundation of Shandong Province(Nos.ZR2020QF086 and ZR2022MF253)Liaocheng University(Nos.318052199,318012023,318051412,31805180101,319190301,and 318051411)。
文摘Wavelength-tunable dissipative solitons and amplifier similaritons have been obtained by inserting all-fiber Mach-Zehnder interferometer(MZI) filters with different free spectral ranges(FSRs) in a Yb-doped mode-locked fiber laser.The MZI filter is fabricated by splicing one segment of seven-core fiber(SCF) between two segments of single-mode fibers.The bandwidth of the filter depends on the FSR of the modulated interference curve and consequently depends on the tapered fiber diameter.Inserting MZI filters with bandwidths in a fiber laser and applying a tensile strain on the tapered SCF,both wavelengthtunable dissipative solitons and amplifier similaritons have been obtained.
基金supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.51875584 and 51875585)the National Key Research and Development Program of China(Grant Nos.2017YFB1104800 and 2018YFB1107803)the Fundamental Research Funds for the Central Universities of Central South University(Grant No.1053320170003).
文摘A novel fiber inline Mach-Zehnder interferometer(MZI)is proposed for simultaneous measurement of curvature and temperature.The sensor composes of single mode-multimode-dispersion compensation-multimode-single mode fiber(MMF-DCF-MMF)structure,using the direct fusion technology.The experimental results show curvature sensitivities of−12.82 nm/m^(−1) and−14.42 nm/m^(−1) in the range of 0−0.65 m^(−1) for two resonant dips,as well as temperature sensitivities of 57.6 pm/and 74.3℃pm/within the range of 20℃℃−150.In addition,℃the sensor has unique advantages of easy fabrication,low cost,high fringe visibility of 24 dB,and high sensitivity,which shows a good application prospect in dual-parameters of sensing of curvature and temperature.
基金This work was funded by the National Natural Science Foundation of China(NSFC)(Grant Nos.41266001,61665007,and 61865013)National Key Research and Development Project from the Ministry of Science and Technology(Grant No.2018YFE0115700)+1 种基金Science and Technology Project of Jiangxi Education Department(Grant No.GJJ180518)Nanchang Hangkong University graduate student innovation special fund project(Grant No.YC2019053).
文摘A Mach-Zehnder interferometer(MZI)for high temperature(1000°C)sensing based on few mode fiber(FMF)was proposed and experimentally demonstrated.The sensor was fabricated by fusing a section of FMF between two single-mode fibers(SMFs).The structure was proven to be an excellent high temperature sensor with good stability,repeatability,and high temperature sensitivity(48.2 pm/C)after annealing process at a high temperature lasting some hours,and a wide working temperature range(from room temperature to 1000 C).In addition,the simple fabrication process and the low cost offered a great potential for sensing in high temperature environments.