Showing papers on "Mach–Zehnder interferometer published in 2016"

16 × 16 non-blocking silicon optical switch based on electro-optic Mach-Zehnder interferometers.

Abstract: We experimentally demonstrate a 16 × 16 non-blocking optical switch fabric with a footprint of 10.7 × 4.4 mm2. The switch fabric is composed of 56 2 × 2 silicon Mach-Zehnder interferometers (MZIs), with each integrated with a pair of TiN resistive micro-heaters and a p-i-n diode. The average on-chip insertion loss at 1560 nm wavelength is ~6.7 dB and ~14 dB for the "all-cross" and "all-bar" states, respectively, with a loss variation of ± 1 dB over all routing paths. The measured rise/fall time of the switch upon electrical tuning is 3.2/2.5 ns. The switching functionality is verified by transmission of 20 Gb/s on-off keying (OOK) and 50 Gb/s quadrature phase-shift keying (QPSK) optical signals.

High-performance and linear thin-film lithium niobate Mach-Zehnder modulators on silicon up to 50 GHz.

Abstract: Compact electro-optical modulators are demonstrated on thin films of lithium niobate on silicon operating up to 50 GHz. The half-wave voltage length product of the high-performance devices is 3.1 V.cm at DC and less than 6.5 V.cm up to 50 GHz. The 3 dB electrical bandwidth is 33 GHz, with an 18 dB extinction ratio. The third-order intermodulation distortion spurious free dynamic range is 97.3 dBHz2/3 at 1 GHz and 92.6 dBHz2/3 at 10 GHz. The performance demonstrated by the thin-film modulators is on par with conventional lithium niobate modulators but with lower drive voltages, smaller device footprints, and potential compatibility for integration with large-scale silicon photonics.

Low-loss and broadband 2 × 2 silicon thermo-optic Mach-Zehnder switch with bent directional couplers.

Abstract: A low-loss and broadband silicon thermo-optic switch is proposed and demonstrated experimentally by using a Mach-Zehnder Interferometer with 2×2 3 dB power splitters based on bent directional couplers (DCs). The bent DCs are introduced here to replace the traditional 2×2 3 dB power splitters based on multimode interferometers or straight DCs, so that one achieves a coupling ratio of ∼50%∶ 50%, as well as low excess loss over a broadband. The demonstrated Mach-Zehnder switch (MZS) has a ∼140 nm bandwidth for an excess loss of 20 dB. The present MZS also shows excellent reproducibility and good fabrication tolerance, which makes it promising for realizing N×N optical switches.

High sensitivity refractive index sensor based on splicing points tapered SMF-PCF-SMF structure Mach-Zehnder mode interferometer

Abstract: The paper proposed and studied a Mach-Zehnder mode interferometric refractive index sensor, which is based on splicing points tapered SMF-PCF-SMF (SMF, single-mode fiber; PCF, photonic crystal fiber) structure. For the reason that the effective refractive index of photonic crystal fiber cladding high-order modes near fiber core are more sensitive to surrounding refractive index changes, the refractive index measurement sensitivity of splicing points tapered SMF-PCF-SMF Mach-Zehnder mode interferometer can be enhanced further through tapering the splicing points. Relations between refractive index measurement sensitivity and photonic crystal fiber length and taper waist diameter are studied through numerical simulations and experiments. Simulation and experimental results show that sensitivity will be increased with the increase of photonic crystal fiber length and the decrease of taper waist diameter. In the refractive range of 1.3333–1.3737, splicing points tapered SMF-PCF-SMF Mach-Zehnder mode interferometer with PCF length of 4 cm and taper waist diameter of 60.4 μm has refractive index measurement sensitivity of 260.8 nm/RIU, compared with sensitivity of 224.2 nm/RIU of direct splicing SMF-PCF-SMF Mach-Zehnder mode interferometer with PCF length of 4 cm, the sensitivity increased by 16.3%. The research shows that the sensing structure is with good linearity and repeatability.

60 dB high-extinction auto-configured Mach-Zehnder interferometer

Abstract: Imperfections in integrated photonics manufacturing have a detrimental effect on the maximal achievable visibility in interferometric architectures. These limits have profound implications for further technological developments in photonics and in particular for quantum photonic technologies. Active optimization approaches, together with reconfigurable photonics, have been proposed as a solution to overcome this. In this Letter, we demonstrate an ultrahigh (>60 dB) extinction ratio in a silicon photonic device consisting of cascaded Mach-Zehnder interferometers, in which additional interferometers function as variable beamsplitters. The imperfections of fabricated beamsplitters are compensated using an automated progressive optimization algorithm with no requirement for pre-calibration. This work shows the possibility of integrating and accurately controlling linear-optical components for large-scale quantum information processing and other applications.

Phase sensing beyond the standard quantum limit with a truncated SU(1,1) interferometer

Abstract: An SU(1,1) interferometer replaces the beamsplitters in a Mach-Zehnder interferometer with nonlinear interactions and offers the potential of achieving high phase sensitivity in applications with low optical powers. We present a novel variation in which the second nonlinear interaction is replaced with balanced homodyne detection. The phase-sensing quantum state is a two-mode squeezed state produced by seeded four-wave-mixing in Rb vapor. Measurements as a function of operating point show that even with $\approx35~\%$ loss this device can surpass the standard quantum limit by 4~dB.

Phase sensitivity at the Heisenberg limit in an SU(1,1) interferometer via parity detection

Abstract: We theoretically investigate the phase sensitivity with parity detection on an SU(1,1) interferometer with a coherent state combined with a squeezed vacuum state. This interferometer is formed with two parametric amplifiers for beam splitting and recombination instead of beam splitters. We show that the sensitivity of phase estimation approaches the Heisenberg limit and give the corresponding optimal condition. Moreover, we derive the quantum Cram\'er-Rao bound of the SU(1,1) interferometer.

Polarization-dependent humidity sensor based on an in-fiber Mach-Zehnder interferometer coated with graphene oxide

Abstract: A polarization-dependent humidity sensor based on an in-fiber Mach-Zehnder interferometer (MZI) coated with graphene oxide (GO) film was proposed. The MZI was constructed by fusion splicing a ∼15-mm long polarization maintaining fiber (PMF) between a waist-enlarged taper and a core-offset. The cladding of the PMF was etched off 10 μm, A GO film with the maximum thickness of 4–5 μm was coated on the etched cladding by optically driven deposition. With the strong hydrophilic of the GO and the characteristics of the MZI, the maximum sensitivity of 0.349 dB/%RH with a good stability at the RH range of 60–77% was obtained, which has a linear correlation coefficient of 98.9%.

Optimization of cascaded fiber tapered Mach–Zehnder interferometer and refractive index sensing technology

Abstract: A novel refractive index sensor with high sensitivity based on Mach–Zehnder interferometer formed by cascaded two single-mode fiber tapers was proposed and experimentally demonstrated The dip of the measured spectrum signal caused by Mach–Zehnder interference shifted obviously when the surrounding refractive index changed The approximate linear relationship between surrounding refractive index and spectrum dip wavelength shift was obtained experimentally The measurement sensitivity up to 1584 nm/RIU was showed with the surrounding RI ranged from 133 to 13792, which meant the measurement resolution about 63 × 10 −6 could be implemented if wavelength shift measurement resolution of the optical spectrum analyzer is 1 pm Meanwhile, its ease of fabrication makes itself a low-cost alternative to existing sensing applications

Particle Path Through a Nested Mach-Zehnder Interferometer

Abstract: Possible paths of a photon passing through a nested Mach-Zehnder interferometer on its way to a detector are analyzed using the consistent histories formulation of quantum mechanics, and confirmed using a set of weak measurements (but not weak values). The results disagree with an analysis by Vaidman [Phys. Rev. A 87, 052104 (2013)], and agree with a conclusion reached by Li et al. [Phys. Rev. A 88, 046102 (2013)]. However, the analysis casts serious doubt on the claim of Salih et al. (whose authorship includes Li et al.) [Phys. Rev. Lett. 110, 170502 (2013)] to have constructed a protocol for counterfactual communication: a channel which can transmit information even though it contains a negligible number of photons.

Ultrasensitive magnetic field sensor based on an in-fiber Mach–Zehnder interferometer with a magnetic fluid component

Abstract: An ultrasensitive magnetic field sensor based on a compact in-fiber Mach–Zehnder interferometer (MZI) created in twin-core fiber (TCF) is proposed, and its performance is experimentally demonstrated. A section of TCF was spliced between two sections of standard single-mode fibers, and then a microchannel was drilled through one core of the TCF by means of femtosecond laser micromachining. The TCF with one microchannel was then immersed in a water-based Fe3O4 magnetic fluid (MF), forming a direct component of the light propagation path, and then sealed in a capillary tube, achieving a magnetic sensing element, which merges the advantages of an MZI with an MF. Experiments were conducted to investigate the magnetic response of the proposed sensor. The developed magnetic field sensor exhibits a linear response within a measurement range from 5 to 9.5 mT and an ultrahigh sensitivity of 20.8 nm/mT, which, to our best knowledge, is 2 orders of magnitude greater than other previously reported magnetic sensors. The proposed sensor is expected to offer significant potential for detecting weak magnetic fields.

Long-Range Distributed Fiber Vibration Sensor Using an Asymmetric Dual Mach–Zehnder Interferometers

Abstract: An asymmetric dual Mach–Zehnder interferometry (ADMZI) design is proposed to achieve distributed fiber vibration sensing at long range. In this structure, we utilized two distributed feedback laser beams and dense wavelength-division multiplexing to significantly reduce the influence of Rayleigh backscattering noise, which will seriously deteriorate the signal noise ratio (SNR) in traditional dual Mach–Zehnder interferometer (DMZI) sensor. At the sensing length of 61 km, the SNR achieved using the ADMZI design is 20 dB higher than that using the DMZI design. Using a positioning algorithm based on the time–frequency analysis, the positioning mean square error can reach 52.5 m at this distance.

Mach-Zehnder interferometric photonic crystal fiber for low acoustic frequency detections

Abstract: Low frequency under-water acoustic signal detections are challenging, especially for marine applications. A Mach-Zehnder interferometric hydrophone is demonstrated using polarization-maintaining photonic-crystal-fiber (PM-PCF), spliced between two single-mode-fibers, operated at 1550 nm source. These data are compared with standard hydrophone, single-mode and multimode fiber. The PM-PCF sensor shows the highest response with a power shift (2.32 dBm) and a wavelength shift (392.8 pm) at 200 Hz. High birefringence values and the effect of the imparted acoustic pressure on this fiber, introducing the difference between the fast and slow axis changes, owing to the phase change in the propagation waves, demonstrate the strain-optic properties of the sensor.

Wavelength and bandwidth-tunable silicon comb filter based on Sagnac loop mirrors with Mach-Zehnder interferometer couplers

Abstract: We propose and experimentally demonstrate a wavelength and bandwidth-tunable comb filter based on silicon Sagnac loop mirrors (SLMs) with Mach-Zehnder interferometer (MZI) couplers. By thermally tuning the MZI couplers in common and differential modes, the phase shift and reflectivity of the SLMs can be changed, respectively, leading to tunable wavelength and bandwidth of the comb filter. The fabricated comb filter has 93 comb lines in the wavelength range from 1535 nm to 1565 nm spaced by ~0.322 nm. The central wavelength can be red-shifted by ~0.462 nm with a tuning efficiency of ~0.019 nm/mW. A continuously tunable bandwidth from 5.88 GHz to 24.89 GHz is also achieved with a differential heating power ranging from 0.00 mW to 0.53 mW.

Highly sensitive refractive index fiber inline Mach–Zehnder interferometer fabricated by femtosecond laser micromachining and chemical etching

Abstract: A High sensitive refractive index (RI) sensor based on Mach–Zehnder interferometer (MZI) in a conventional single-mode optical fiber is proposed, which is fabricated by femtosecond laser transversal-scanning inscription method and chemical etching A rectangular cavity structure is formed in part of fiber core and cladding interface The MZI sensor shows excellent refractive index sensitivity and linearity, which exhibits an extremely high RI sensitivity of −17197 nm/RIU (refractive index unit) with the linearity of 09996 within the refractive index range of 13371–13407 The experimental results are consistent with theoretical analysis

Optical Fiber Relative Humidity Sensor Based on Inline Mach–Zehnder Interferometer With ZnO Nanowires Coating

Abstract: A simple optical fiber relative humidity (RH) sensor was proposed and demonstrated using a dumbbell-shaped inline Mach–Zehnder interferometer (IMZI) as a probe. The humidity sensor was constructed by coating the tapered waist region of the IMZI with ZnO nanowires. Based on an optical interferometric technique, the response of the sensor probe was examined by changing the RH within a range of 35%–60% RH. A wavelength shift of 0.490 nm was achieved for a humidity variation from 35% to 60% RH. It was also found that the sensitivity of IMZI-based sensor improved from 0.0002 to 0.020 nm/%RH with the ZnO coating.

Slow light Mach-Zehnder interferometer as label-free biosensor with scalable sensitivity

Abstract: The design, fabrication, and characterization of a label-free Mach-Zehnder interferometer (MZI) optical biosensor that incorporates a highly dispersive one-dimensional (1D) photonic crystal in one arm are presented. The sensitivity of this slow light MZI-based sensor scales with the length of the slow light photonic crystal region. The numerically simulated sensitivity of a MZI sensor with a 16 μm long slow light region is 115,000 rad/RIU-cm, which is sevenfold higher than traditional MZI biosensors with millimeter-length sensing regions. An experimental bulk refractive index detection sensitivity of 84,000 rad/RIU-cm is realized and nucleic acid detection is also demonstrated.

A Silicon Photonic PAM-4 Modulator Based on Dual-Parallel Mach–Zehnder Interferometers

Abstract: We present a silicon photonic dual-parallel Mach–Zehnder modulator (MZM) operating near 1550 nm used for four-level pulse amplitude modulation (PAM-4). The differential and integral nonlinearities of the device are investigated. A driving scheme and a biasing method that improves the linearity and PAM operation of the device are presented. The measured second harmonic distortion and two-tone, third-order intermodulation spurious-free dynamic range are 75 $\mbox{dB}\cdot\mbox{Hz}^{1/2}$ and 86 $\mbox{dB}\cdot\mbox{Hz}^{3/2}$ , respectively. We further investigate the performance of the device in a short-reach transmission system. We report a successful 50-Gbaud single-wavelength transmission of PAM-4 over 2 km of single-mode fiber (SMF) below hard decision pre forward error correction (pre-FEC) threshold of $4.4 \times 10^{-3}$ .

Ultralinear heterogeneously integrated ring-assisted Mach-Zehnder interferometer modulator on silicon

Abstract: A linear modulator is indispensable for radio frequency photonics or analog photonic link applications where high dynamic range is required. There is also great interest to integrate the modulator with other photonic components, to create a photonic integrated circuit for these applications, with particular focus on silicon photonics integration in order to take advantage of complementary metal–oxide–semiconductor compatible foundries for high-volume, low-cost devices. However, all silicon modulators, including the highest performing Mach–Zehnder interferometer (MZI) type, have poor linearity, partially due to the inherent nonlinearity of the MZI transfer characteristic, but mostly due to the nonlinearity of silicon’s electro-optic phase shift response. In this work, we demonstrate ultralinear ring-assisted MZI (RAMZI) modulators, incorporating heterogeneously integrated III–V multiple quantum wells on silicon phase modulation sections to eliminate the nonlinear silicon phase modulation response. The heterogeneously integrated III–V/Si RAMZI modulators achieve record-high spurious free dynamic range (SFDR) for silicon-based modulators, as high as 117.5 dB·Hz2/3 at 10 GHz for a weakly coupled ring design, and 117 dB·Hz2/3 for a strongly coupled ring design with higher output power. This is a higher SFDR than typically obtained with commercial lithium niobate modulators. This approach advances integrated modulator designs on silicon for applications in compact and high-performance analog optical systems.

60dB high-extinction auto-configured Mach--Zehnder interferometer

Abstract: Imperfections in integrated photonics manufacturing have a detrimental effect on the maximal achievable visibility in interferometric architectures. These limits have profound implications for further photonics technological developments and in particular for quantum photonics technologies. Active optimisation approaches, together with reconfigurable photonics, have been proposed as a solution to overcome this. In this paper, we demonstrate an ultra-high (>60 dB) extinction ratio in a silicon photonic device consisting of cascaded Mach-Zehnder interferometers, in which additional interferometers function as variable beamsplitters. The imperfections of fabricated beamsplitters are compensated using an automated progressive optimization algorithm with no requirement for pre-calibration. This work shows the possibility of integrating and accurately controlling linear-optical components for large-scale quantum information processing and other applications.

Optical temperature sensor with enhanced sensitivity by employing hybrid waveguides in a silicon Mach-Zehnder interferometer.

Abstract: We report on a novel design of an on-chip optical temperature sensor based on a Mach-Zehnder interferometer configuration where the two arms consist of hybrid waveguides providing opposite temperature-dependent phase changes to enhance the temperature sensitivity of the sensor. The sensitivity of the fabricated sensor with silicon/polymer hybrid waveguides is measured to be 172 pm/°C, which is two times larger than a conventional all-silicon optical temperature sensor (~80 pm/°C). Moreover, a design with silicon/titanium dioxide hybrid waveguides is by calculation expected to have a sensitivity as high as 775 pm/°C. The proposed design is found to be design-flexible and robust to fabrication errors.

Intensity-modulated abrupt tapered Fiber Mach-Zehnder Interferometer for the simultaneous sensing of temperature and curvature

Abstract: An abrupt tapered fiber In-Line Mach-Zehnder Interferometer sensor for simultaneous measurement of temperature and curvature is proposed and experimentally demonstrated. The sensor head is fabricated by arcing Corning SMF-28 using a commercial arc fusion splicer. The individual parameters discrimination was achieved by manipulating the unequal sensitivities of optical power to temperature and curvature obtained at two wavelengths within the sensing spectrum. The curvature and temperature sensitivities at λ1 (1537 nm) and λ2 (1568.7 nm) were found to be 11.8264 dBm/m−1, 12.4885 dBm/m−1 and 0.0829 dBm/°C, 0.0833 dBm/°C, respectively. The experimental results show unperturbed readings with rms deviation of ±0.1801 m−1 and ±0.0826 °C, for curvature and temperature measurements, respectively, through measurement of optical power response of the sensor. With this simultaneous sensing technique, the proposed sensor can be deployed for many field applications such as nondestructive structural health monitoring of civil infrastructure.

Fabrication and characterization of cascaded tapered Mach-Zehnder interferometer for refractive index sensing

Abstract: A highly sensitive glucose detection refractometer based on Mach- Zehnder Interferometer (MZI) formed by two cascaded tapered joints by using a fusion splicer was proposed and experimentally demonstrated. A section of 40 mm single mode fiber is spliced by arcing function with cascaded tapered joint between two single mode fibers to construct MZI. Experimental results show that the transmission spectrum of the proposed cascaded device has a blue shift with the decreasing concentration of glucose. The sensitivity coefficient of 380 nm/RIU was acquired within the refractive index range from 1.333 RIU to 1.349 RIU. This result shows that the proposed structure can be used as a sensor to detect glucose concentration, which enables its importance in physiological and biomedical applications. Its ease of fabrication makes this device itself a low-cost alternative to existing sensing applications.

16 × 16 silicon Mach–Zehnder interferometer switch actuated with waveguide microheaters

Abstract: We experimentally demonstrate a 16×16 reconfigurably nonblocking optical switch fabric using a Benes architecture. The switch fabric consists of 56 2×2 Mach–Zehnder interferometer based elementary switches, with each integrated with a pair of waveguide microheaters. The average on-chip insertion loss is ∼5.2 dB for both of the “all-cross” and the “all-bar” states, with a loss variation of 1 dB over all routing paths. The cross talk for all switching states is better than −30 dB. The switching time of the switch element is about 22 μs. The switching functionality is verified by transmission of a 40 Gb/s quadrature phase-shift keying optical signal.

Design of optical reversible logic gates using electro-optic effect of lithium niobate based Mach–Zehnder interferometers

Abstract: In recent years reversible logic has come as a promising solution in the optical computing domain. In reversible gates, there is one-to-one mapping between input and output, causing no loss of information. Reversible gates are useful for application in low power complementary metal-oxide semiconductors, with less dissipation, and in quantum computing. These benefits can be utilized by implementing reversible gate structures in the optical domain. In this paper, basic reversible Feynman and Fredkin logic gates using a lithium niobate based Mach-Zehnder interferometer are proposed. The different applications utilizing the proposed structures are also explained in this study.

Interactive tutorial to improve student understanding of single photon experiments involving a Mach-Zehnder Interferometer

Abstract: We have developed and evaluated a Quantum Interactive Learning Tutorial (QuILT) on a Mach-Zehnder Interferometer with single photons to expose upper-level students in quantum mechanics courses to contemporary quantum optics applications. The QuILT strives to help students develop the ability to apply fundamental quantum principles to physical situations in quantum optics and explore the differences between classical and quantum ideas. The QuILT adapts visualization tools to help students build physical intuition about counter-intuitive quantum optics phenomena with single photons including a quantum eraser setup and focuses on helping them integrate qualitative and quantitative understanding. We discuss findings from in-class evaluations.