Correlated photon pairs are the core resources for photonic quantum information technology. Multiplexed quantum light sources can appreciably improve the efficiency of quantum information processing. Here, we develop a coupled-mode mean-field model and its corresponding semiclassical theory analysis to investigate the multiple parametric-gain sidebands in dispersion-oscillation fiber-ring cavities. We present a cycle transfer matrix method to give the analytic expressions for parametric gain. From this, we can reach a physical insight, that is additional degree of freedom introduced by the modulation along fiber length is responsible for the multiple parametric-gain sidebands, where the underlying mechanism is the quasi-phase matching of four-wave mixing. Two twin signal and idler photons generated from parametric-gain sidebands are appreciably of frequency and temporal correlation, revealing promising applications in frequency-multiplexed photon pair sources. When we construct an optical cavity with spliced single mode fiber and dispersion shifted fibers, numerous parametric-gain sidebands grow in the vicinity of zero group-velocity-dispersion wavelengths of two fibers, i.e., 1310 nm and 1550 nm, both corresponding to low transmission loss windows of fibers. Therefore, frequency-multiplexed quantum light sources established on dispersion-oscillation fiber-ring cavities have the advantages in economy, remote transmission, scalability and compatibility with fiber communication network. Our work offers inspiration for the development of a multiplexed quantum light source.
Correlated photon pairs are the core resources for photonic quantum information technology. Multiplexed quantum light sources can appreciably improve the efficiency of quantum information processing. Here, we develop a coupled-mode mean-field model and its corresponding semiclassical theory analysis to investigate the multiple parametric-gain sidebands in dispersion-oscillation fiber-ring cavities. We present a cycle transfer matrix method to give the analytic expressions for parametric gain. From this, we can reach a physical insight, that is additional degree of freedom introduced by the modulation along fiber length is responsible for the multiple parametric-gain sidebands, where the underlying mechanism is the quasi-phase matching of four-wave mixing. Two twin signal and idler photons generated from parametric-gain sidebands are appreciably of frequency and temporal correlation, revealing promising applications in frequency-multiplexed photon pair sources. When we construct an optical cavity with spliced single mode fiber and dispersion shifted fibers, numerous parametric-gain sidebands grow in the vicinity of zero group-velocity-dispersion wavelengths of two fibers, i.e., 1310 nm and 1550 nm, both corresponding to low transmission loss windows of fibers. Therefore, frequency-multiplexed quantum light sources established on dispersion-oscillation fiber-ring cavities have the advantages in economy, remote transmission, scalability and compatibility with fiber communication network. Our work offers inspiration for the development of a multiplexed quantum light source.
A fiber-based photon-pair source in the telecom C-band is suitable for quantum information science including quantum communications.Spontaneous four-wave mixing effects are known to create photon pairs that are slightly detuned from the pump wavelength only in the anomalous groupvelocity-dispersion (GVD) regime.Here, we achieve high-quality photon-pair generation slightly detuned from the pump wavelength in the normal GVD regime through a dispersion shifted fiber, for the first time.The photon pairs in C-band exhibit strong temporal correlation with each other and excellent heralded anti-bunching property.This photon-pair generation scheme can be exploited as telecom-band quantum light sources for quantum information applications.A non-classical light source is one of the key elements of quantum information processing systems, and several types of these sources have been investigated, including molecules [1], trapped atoms [2], quantum dots [3], diamond vacancy centers [4], spontaneous parametric down-conversion (SPDC) [5], and spontaneous fourwave mixing (SFWM) [6]. Among these processes, the SPDC and the SFWM processes create quantumcorrelated photon pairs from one and two pump photons, respectively, and both processes require satisfying the energy conservation as well as phase matching [7].Typically, the nonlinear coefficient of SPDC in second-order nonlinear crystals is larger than that of SFWM in amorphous single mode optical fibers as SFWM is a third-order nonlinear process.In the case of several hundred meters long single-mode fibers, however, the SFWM conversion efficiency from pump beam to photon pairs can be similar with that of the SPDC process in nonlinear crystals.In addition, the fiber based photon-pair sources are able to be directly coupled to fiber systems with negligible coupling loss, but waveguide-to-fiber coupling efficiency of a periodically poled SPDC crystal is reported about 50% [8].The SFWM process has been studied intensively for the fiber-based photon generation [6, 9-20] for quantum information applications including quantum key distribution.Photon-pair generation via SFWM is active near the zero group-velocity-dispersion (GVD) wavelength, λ ZGVD , in the anomalous GVD regime [6, 9-15] or normal GVD regime [16][17][18][19][20].In the normal GVD regime, the wavelength of the generated photon pairs is significantly detuned from the pump wavelength.In this case, Raman noise can be avoided, but the generated photon pair do not exhibit telecom-band wavelength together.On the other hand, in the anomalous GVD regime, the wavelength of the generated photon pair is slightly detuned from the pump in the telecom C-band and is strongly power dependent [16].Since the wavelength of the generated pair is sensitive to the λ ZGVD of the generation medium, several types of commercial fibers which have λ ZGVD in the telecom C-band have been investigated as the telecom C-band pair sources.Even if commercial optical fibers have small tolerances in their physical properties, it is common to have sizeable λ ZGVD variance along an optical fiber [21,22].Therefore, the precise measurement of the GVD spectrum is required, but it is often tricky with short length optical fibers.One way to overcome this problem is engineering the dispersion of a commercial fiber by heating and pulling the fiber, but this method is an ambitious research field [19,20,23].On the other hand, if a slightly detuned pair can be generated in the normal GVD regime, the constraint for the λ ZGVD of medium can be weakened, but it has not been reported to the best of our knowledge because phases are mis-matched in this regime due to the Kerr effects of the media.
High coherent frequency-entangled photons at telecom band are critical in quantum information protocols and quantum tele-communication. While photon pairs generated by spontaneous parametric down-conversion in nonlinear crystal or modulation instability in optical fiber exhibit random fluctuations, making the photons distinguishable among consecutive roundtrips. Here, we demonstrate a frequency-entangled photons based on parametric instability in an active fiber ring cavity, where periodic modulation of dispersion excites parametric resonance. The characteristic wave number in parametric instability is selected by the periodic modulation of resonator, and stable patterns with symmetric gains are formed. We find that the spectra of parametric instability sidebands possess a high degree of coherence, which is verified by the background-free autocorrelation of single-shot spectra. Two photon interference is performed by a fiber-based Mach-Zehnder interferometer without any stabilization. We obtain a Hong-Ou-Mandel interference visibility of 86.3% with a dip width of 4.3 mm. The correlation time measurement exhibits a linewidth of 68.36 MHz, indicating high coherence and indistinguishability among the photon pairs. Our results proves that the parametric instability in active fiber cavity is effective to generate high coherent frequency-entangled photon pairs, which would facilitate subsequent quantum applications.
We demonstrate an all-fiber broadband photon pair source based on four wave mixing (FWM) process in dispersion flattened highly non-linear fiber (DF-HNLF). The fiber exhibits a zero dispersion slope near 1550 nm, allowing phase-matched FWM over entire S, C, and L bands and thus efficient generation of signal and idler photons. A comparative theoretical study between conventional dispersion-shifted fiber (DSF) and DF-HNLF highlights the spectral range differences in the generation of photon pairs. We measure coincidence counts at three different sets of wavelengths. To study the effects of Raman scattering, which acts as noise source in these types of fibers, we calculate the correlationg(2)(τ)at different pump powers. We use stimulated emission tomography to characterize the generation of photon pairs across the S, C, and L bands. We show that DF-HNLF is an ideal medium for generating correlated photons over a broad spectral range (>100nm), making it suitable for frequency-multiplexed quantum communication systems. We estimate the photon pair generation efficiency to be 0.05mW−2/pulse.
The ultimate goal of quantum information science is to build a global quantum network, which enables quantum resources to be distributed and shared between remote parties. Such a quantum network can be realized using only fiber elements, thus deriving the advantages of low transmission loss, low cost, scalability, and integrability through mature fiber communication techniques such as dense wavelength division multiplexing. Hence high-quality entangled-photon sources based on fibers are in high demand. Here we report multiplexed polarization- and time-bin-entangled photon-pair sources based on the dispersion-shifted fiber operating at room temperature. The associated high quality of entanglement is characterized using interference, Bell’s inequality, and quantum state tomography. The simultaneous presence of both types of entanglement in multi-channel pairs of a 100-GHz dense wavelength division multiplexing device indicates a great capacity in distributing entangled photons over multiple users. Our design provides a versatile platform and takes a big step toward constructing an all-fiber quantum network.
The ultimate goal of quantum information science is to build a global quantum network, which enables quantum resources to be distributed and shared between remote parties. Such a quantum network can be realized using only fiber elements, thus deriving the advantages of low transmission loss, low cost, scalability, and integrability through mature fiber communication techniques such as dense wavelength division multiplexing. Hence high-quality entangled-photon sources based on fibers are in high demand. Here we report multiplexed polarization- and time-bin-entangled photon-pair sources based on the dispersion-shifted fiber operating at room temperature. The associated high quality of entanglement is characterized using interference, Bell's inequality, and quantum state tomography. The simultaneous presence of both types of entanglement in multichannel pairs of a 100-GHz dense wavelength division multiplexing device indicates a great capacity in distributing entangled photons over multiple users. Our design provides a versatile platform and takes a big step toward constructing an all-fiber quantum network.
Fiber optical parametric oscillators are being busily investigated as sources of classical light, but are comparatively neglected as potential quantum light sources. Squeezed light is a crucial resource for emerging quantum technologies for computing, communications, and measurement. The direct generation of squeezed light inside optical fiber is of particular interest due to minimal material loss, desirable mode properties and compatibility with long-distance optical networks. Here, we describe a novel all-fiber continuous-wave optical parametric oscillator developed with the aim of generating squeezed light. Our device is based on a 10 cm Fabry-Perot cavity formed by two high-reflectivity fiber Bragg gratings written directly into a single section of photonic crystal fiber. This enables low-loss optical feedback and strongly resonance-enhanced four-wave mixing, with a cavity finesse of up to 400. We observe resonance-enhanced four-wave mixing in these devices, demonstrating a step towards their application as quantum light sources.