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Accepted papers to appear in an upcoming issue

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Optimal design of Er/Yb co-doped fiber amplifiers with an Yb-band fiber Bragg grating

Qun Han, Wenchuan Yan, Yunzhi Yao, Yaofei Chen, and T. Liu

Doc ID: 256644 Received 05 Jan 2016; Accepted 03 Feb 2016; Posted 04 Feb 2016  View: PDF

Abstract: In this paper, Er/Yb co-doped fiber amplifiers (EYDFAs) with an Yb-band fiber Bragg grating (FBG) at the pump end to improve the performance of the amplifier is systematically studied. The influence of the reflectivity and center-wavelength of the FBG, and the gain-fiber length on the performance of an EYDFA are numerically analyzed. The results show that the wavelength of the FBG has a critical influence on the efficiency of the EYDFA, whereas the requirement to its reflectivity is much relaxed. It is an effective and very promising way to improve the efficiency of a high-power pumped EYDFA by introducing a suitable Yb-band FBG at the pump end. Based on the analysis of the underlying principles, suggestions for the practical design and possible further improving strategies are also proposed.

Stochastic Collocation for Device-level Variability Analysis in Integrated Photonics

Yufei Xing, Domenico Spina, ang li, Tom Dhaene, and Wim Bogaerts

Doc ID: 251989 Received 14 Oct 2015; Accepted 26 Jan 2016; Posted 26 Jan 2016  View: PDF

Abstract: We demonstrate the use of stochastic collocation to assess the performance of photonic devices under the effect of uncertainty. This approach combines high accuracy and efficiency in analyzing device variability with the ease of implementation of sampling-based methods. Its flexibility makes it suitable to be applied to a large range of photonic devices. We compare the stochastic collocation method to a Monte Carlo technique on a numerical analysis of the variability in silicon directional couplers.

Periodic structural defects in Bragg grating and its application in multi-wavelength devices

Yuechun Shi, Rulei Xiao, Renjia Guo, Chen Ting, Lijun Hao, and Xiangfei Chen

Doc ID: 253631 Received 09 Nov 2015; Accepted 12 Jan 2016; Posted 15 Jan 2016  View: PDF

Abstract: We present that periodic structural defects (PSDs) along the Bragg grating can lead the Bragg wavelength to a red shift. This effect is completely proved by numerical calculation and theory analysis. We find that the red-shift is determined by the defect size and the period of the defects. The Bragg wavelength can be well tuned by properly designing the PSDs and it may provide an alternative method to fabricate the grating based multi-wavelength devices, including the optical filter arrays and laser arrays. In regard of the wavelength precision, the proposed method has an obvious advantage over the traditional one, where the grating periods are changed in ultra-small steps. In addition, the proposed method can maintain the grating strength when tuning the wavelength. It shows an advantage over a recently improved method, where gratings with two periods are stitched alternately to average the Bragg wavelength.

High-energy plain and composite pulses in a laser modeled by the complex Swift-Hohenberg equation

Sofia Latas

Doc ID: 252953 Received 29 Oct 2015; Accepted 10 Jan 2016; Posted 15 Jan 2016  View: PDF

Abstract: In this work, new plain and composite high energy solitons of the cubic-quintic Swift-Hohenberg equation were numerically found. Starting from a composite pulse found by Soto-Crespo and Akhmediev and changing some parameter values allowed us to find these high energy pulses. We also found the region in the parameters space, in which these solutions exist. Some pulse characteristics, namely, temporal and spectral profiles and chirp are presented. The study of the pulse energy shows its independence of the dispersion parameter but its dependence on the nonlinear gain. An extreme amplitude pulse has also been found.

Optical pulse repetition rate multiplication based on series-coupled double-ring resonator

Xiaowei Dong, Qiangqiang Zhang, and Xu Mengzhen

Doc ID: 251088 Received 30 Sep 2015; Accepted 10 Jan 2016; Posted 12 Feb 2016  View: PDF

Abstract: In this paper, optical pulse repetition rate multiplication based on series-coupled double-ring resonator is proposed. Firstly, the spectral characteristic of series-coupled double-ring resonator is investigated and the optimum coupling coefficients to achieve periodic flat-top passband are obtained. Then, high-quality pulse repetition rate multiplication is realized by periodically filtering out spectral lines of input pulse train. Different multiplication factor N =2, 3, 4, 5 can be obtained by adjusting ring radii. In addition, compared with single-ring resonator, multiplied output pulse train by series-coupled double-ring resonator exhibits much better amplitude uniformity.

Design of a single all-silicon ring resonator with a 150 nm FSR and a 100 nm tuning range around 1550 nm

ang li, Huang Qiangsheng, and Wim Bogaerts

Doc ID: 251933 Received 04 Nov 2015; Accepted 05 Jan 2016; Posted 15 Jan 2016  View: PDF

Abstract: We present a novel and simple method to obtain an ultra-wide free spectral range (FSR) silicon ring resonator together with a tuning range covering the entire spectrum from 1500 nm to 1600 nm. A ring resonator with a large FSR together with a high Q factor, high tuning efficiency, low fabrication cost and complexity is desired for many applications. In this paper, we introduce a novel way to make such a ring resonator, which takes advantage of the well known resonance-splitting phenomenon. It is a single ring resonator with a FSR more than 150 nm around 1550 nm and has an easy thermo-optic tunability which can produce a tuning range around 90 nm or even more. Moreover, the device is simple to implement and can be fabricated in standard CMOS technology without requiring any kind of complicated processing or extra materials. The potential applications include single mode laser cavities, WDM filters, (de)multiplexers, optical sensors and integrated reflectors.

Wavelet modulus maxima method for online wavelength location of pulsed lidar in CO2 DIAL detection

Chengzhi Xiang, Xin Ma, Ailin Liang, Gong Wei, and Feiyue MAO

Doc ID: 252356 Received 20 Oct 2015; Accepted 05 Jan 2016; Posted 15 Jan 2016  View: PDF

Abstract: Differential absorption lidar (DIAL) is an excellent technology for atmospheric CO2 detection. However, the accuracy and stability of transmitted online wavelength are strictly required in a DIAL system. The fluctuation of a tunable pulsed laser system is relatively more serious than that of other laser sources, and this condition leads to a large measurement error for the lidar signal, especially under rapid atmospheric aerosol and cloud changes. These concerns pose a significant challenge in online wavelength calibration. This study proposes a method based on wavelet modulus maxima for the accurate online wavelength calibration of pulsed laser. Because of the different propagation characteristics of the wavelet transform modulus maxima between signal and noise, the singularities of a signal can be obtained by detection of the local modulus maxima in the wavelet transform maximum at fine scales. Simulated analysis shows that the method is superior to general method such as quintic polynomial fitting and can steadily maintain high calibration precision at different Signal to Noise Ratios (SNRs). Lastly, sixteen groups of real experiments were conducted to verify the simulated analysis. Compared with other methods, the method proposed in this study improves the accuracy of online wavelength calibration. In addition, a unique characteristic of the proposed method is that it can suppress noises in the process of wavelength calibration, which makes it has a significant advantage in accurate online wavelength calibration with a low SNR.

Long-period grating inscription on polymer functionalized optical microfibers and its applications in optical sensing

Yuhang Li, Zhongyang Xu, and Lijun Wang

Doc ID: 249089 Received 01 Sep 2015; Accepted 04 Jan 2016; Posted 05 Jan 2016  View: PDF

Abstract: We demonstrated long-period grating (LPGs) inscription on polymer functionalized optical microfibers and its applications in optical sensing. The LPG inscription on optical microfiber is enabled by PMMA jacket on it via point-by-point ultraviolet laser exposure. For a 2 mm-long microfiber LPG (MLPG) inscribed on optical microfiber with a diameter of 5.4 μm, a resonant dip of 15 dB at 1377 nm was observed. This MLPG showed a high sensitivity of strain and axial force, i.e., -1.93 pm/με and -867 μN/nm, respectively. Although the intrinsic temperature sensitivity of the LPGs is relatively low, i.e., -12.75 pm/°C, it can be increased to be -385.11 pm/°C by appropriate sealing. Benefited from the small footprint and high sensitivity, MLPGs could have potential applications in optical sensing of strain, axial force and temperature.

Fabrication and Application of a Graphene Polarizer with Strong Saturable Absorption

Lilin Yi, Weixiong Li, Ran Zheng, Zhenhua Ni, and Weisheng Hu

Doc ID: 252307 Received 20 Oct 2015; Accepted 21 Dec 2015; Posted 23 Dec 2015  View: PDF

Abstract: By transferring 100-nm gold coated CVD monolayer graphene onto the well-polished surface of D-shape fiber, we achieve a graphene in-line polarizer with high polarization extinction ratio of ~27 dB and low insertion loss of 5 dB @1550nm, meanwhile achieve strong saturable absorption effect of 14%. The manufacture of this graphene in-line polarizer also simplify the graphene transfer process. To explore the potential applications of the new device, we also demonstrate noise-like pulse generation and supercontinuum spectrum generation. By launching the designed graphene device into a fiber ring laser cavity, 51-nm bandwidth noise-like pulse is obtained. Then launching the high power noise-like pulse into high nonlinear fiber, 1000-nm wide supercontinuum spectrum is obtained, which is favorable for sensing and nonlinearities scientific fields.

Bessel Gauss photon beams with fractional order vortex propagation in weak non-Kolmogorov turbulence

YiXin Zhang, Gao Jie, Yu Zhu, Zhengda Hu, Dong Wang, and cheng jian

Doc ID: 252458 Received 21 Oct 2015; Accepted 21 Dec 2015; Posted 23 Dec 2015  View: PDF

Abstract: We model the effects of the weak fluctuations on the probability densities and the normalized powers of vortex models the Bessel Gauss photon beams with fractional topological charge in paraxial non-Kolmogorov turbulence channel. We find that probability density of signal vortex models is a function of deviation position from the center of photon beam, and the farther away from the beam center it is, the smaller the probability density has. fractional topological charge, the average probability densities of signal/crosstalk vortex modes oscillate along the beam radius except the half-integer order. When the beam waist of photon source increases or the coherence radius of non-Kolmogorov turbulence decreases, the average probability density of the signal vortex mode drops. The peak of the average probability density of crosstalk vortex modes shifts to outward of the beam center as beam waist gets larger. In the nearby region of beam center, the larger the topological charge deviation, the smaller the beam waist and the smaller the turbulence coherence radius are, the lower average probability densities of crosstalk vortex modes are. Lower coherence radius or beam waist can give rise to less reducing of the normalized powers of the signal vortex modes, which is opposite to the normalized powers of crosstalk vortex modes.

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