Few mode Er^3+-doped fiber with micro-structured core for mode division multiplexing in the C-band

Cocq, Guillaume Le; Quiquempois, Yves; Rouge, Antoine Le; Bouwmans, Géraud; Hamzaoui, Hicham El; Delplace, Karen; Bouazaoui, Mohamed; Bigot, Laurent

doi:10.1364/oe.21.031646

Cited by 46 publications

(10 citation statements)

References 14 publications

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“…It includes a ground state, metastable state, and excited state, which is suitable to realize the population inversion between the metastable state and ground state to amplify a signal light whose wavelength is around the 1550 nm window (C-band). We used the Giles and Desurvire model to carry out the analyses upon the population conversion, which is widely used in simulations for fiber amplifiers [29][30][31][32][33]. Owing to the lifetime of the Erbium ion in the metastable state, which is much larger than that in the excited state, the particles of the excited state can be ignored; therefore, the model is considered as a two-level system.…”

Section: Theorymentioning

confidence: 99%

Two-Layer Erbium-Doped Air-Core Circular Photonic Crystal Fiber Amplifier for Orbital Angular Momentum Mode Division Multiplexing System

Zhang

Han

et al. 2019

Crystals

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Orbital angular momentum (OAM) mode-division multiplexing (MDM) has recently been under intense investigations as a new way to increase the capacity of fiber communication. In this paper, a two-layer Erbium-doped fiber amplifier (EDFA) for an OAM multiplexing system is proposed. The amplifier is based on the circular photonic crystal fiber (C-PCF), which can maintain a stable transmission for 14 OAM modes by a large index difference between the fiber core and the cladding. Further, the two-layer doped region can balance the amplification performance of different modes. The relationship between the performance and the parameters of the amplifier is analyzed numerically to optimize the amplifier design. The optimized amplifier can amplify 18 modes (14 OAM modes) simultaneously over the C-band with a differential mode gain (DMG) lower than 0.1 dB while keeping the modal gain over 23 dB and noise figure below 4 dB. Finally, the fabrication tolerance and feasibility are discussed. The result shows a relatively large fabrication tolerance in the OAM EDFA parameters.Crystals 2019, 9, 156 2 of 10 capacity in a MDM system [5]. For communications using OAM beams, there are two key problems to be solved. One is the optical vortex generation, which is the most fundamental technique to implement OAM multiplexing. The optical vortex can be generated by a variety of schemes, such as spatial light modulator [6] and modified interference of different modes [7]. A liquid-crystal spatial light modulator is another promising scheme for generating OAM modes, which exhibits some good properties including simplicity, high efficiency, and reconfiguration [8][9][10]. Another is the optical vortex beam transmission, which needs the fiber supporting OAM modes. In current research, the ring fiber was designed mostly to transmit OAM modes [11][12][13][14][15]. The circular photonic crystal fiber (C-PCF) was also proposed as a potential OAM fiber structure [16][17][18][19]. One fiber can transmit several dozens of mutually orthogonal modes. To date, terabit data transmission based on an OAM fiber has been demonstrated [20]. The transmission distance of the OAM mode in fibers has already reached 50 km [21]. However, many techniques are still needed for handling the implementation of long-haul MDM systems based on OAM modes. OAM carrier signal amplification is one of the critical techniques.The Erbium-doped fiber amplifier (EDFA) not only allows the light signal to be amplified online directly but also possesses the same range between amplification wavelength and the low loss wavelength of optical fibers, which is suitable for MDM systems based on OAM modes. However, unlike the single-mode fiber amplifier, there are tens (even dozens) of modes in the OAM fiber amplifier. The transverse distribution of each mode is different. The biggest difference of these mode gains was defined as differential mode gain (DMG) [22]. DMG should be low enough to ensure approximately equal amplification of the multimode in the fiber.In recent studies, most designs...

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Section: Theorymentioning

confidence: 99%

Two-Layer Erbium-Doped Air-Core Circular Photonic Crystal Fiber Amplifier for Orbital Angular Momentum Mode Division Multiplexing System

Zhang

Han

et al. 2019

Crystals

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“…The development of in-line OAM mode amplifiers is essential for the serious consideration of fiber communication network based on OAM modes. Similar to few-mode erbium-doped fiber amplifiers (FM-EDFAs) [9,10] used in few-mode transmission, the differential modal gain (DMG) for independent OAM modes will be a key characteristic of OAM EDFAs and must be minimized to optimize the system performance.…”

Section: Introductionmentioning

confidence: 99%

Amplification of 12 OAM Modes in an air-core erbium doped fiber

Kang¹,

Gregg²,

Jung³

et al. 2015

Opt. Express

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Abstract:We theoretically propose an air-core erbium doped fiber amplifier capable of providing relatively uniform gain for 12 orbital angular momentum (OAM) modes (|L| = 5, 6 and 7, where |L| is the OAM mode order) over the C-band. Amplifier performance under core pumping conditions for a uniformly doped core for each of the supported pump modes (110 in total) was separately assessed. The differential modal gain (DMG) was found to vary significantly depending on the pump mode used, and the minimum DMG was found to be 0.25 dB at 1550 nm provided by the OAM (8,1) pump mode. A tailored confined doping profile can help to reduce the pump mode dependency for core pumped operation and help to increase the number of pump modes that can support a DMG below 1 dB. For the more practical case of cladding-pumped operation, where the pump mode dependency is almost removed, a DMG of 0.25 dB and a small signal gain of >20 dB can be achieved for the 12 OAM modes across the full Cband.

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“…Although it presents good results, the optimization method used in [8] and [9] require a fairly timeconsuming numerical solution for the rate and propagation equations describing the behavior of the FM-EDFA. For WDM signals, the optimization procedure significant computational effort, since the necessary processing is much higher than that in the single channel case.…”

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confidence: 99%