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Watt-level and spectrally flat mid-infrared supercontinuum in fluoroindate fibers

Francis Theberge, nancy bérubé, Samuel Poulain, Solenn Cozic, Louis-Rafaël Robichaud, Martin Bernier, and Real Vallee

Doc ID: 322969 Received 12 Feb 2018; Accepted 17 Apr 2018; Posted 19 Apr 2018  View: PDF

Abstract: We report on infrared supercontinuum (SC) generation in step-index fluoroindate based fiber by using an all-fiber laser source. In comparison to widely used ZBLAN fibers for high-power mid-infrared (MIR) SC generation, fluoroindate fibers have multiphoton absorption edges at significantly longer wavelengths and can sustain similar power densities. Recent development highlighted in the present study allowed the production of fluoroindate fibers with MIR background loss of 2 dB/km, which is similar or even better than for ZBLAN fibers. By using an all-fiber picosecond laser source based on an erbium amplifier followed by a thulium power amplifier, we demonstrate the generation of 1.0 W infrared SC spanning over 2.25 octaves from 1 μm to 5 μm. The generated MIR SC also exhibits high spectral flatness with a 0.6 dB spectral bandwidth from 1.91 μm to 4.77 μm and an average power 2 orders of magnitude greater than in previous demonstrations with a similar spectral distribution.

Ultraflat, Broadband and Highly Coherent Supercontinuum Generation in All-solid Microstructured Optical Fibers with All-normal Dispersion

Chunlei Huang, Meisong Liao, wanjun bi, Xia Li, Lili Hu, Long Zhang, Longfei Wang, Guanshi Qin, Tianfeng Xue, Danping Chen, and Weiqing Gao

Doc ID: 320692 Received 26 Jan 2018; Accepted 14 Apr 2018; Posted 17 Apr 2018  View: PDF

Abstract: High flatness, wide bandwidth and high coherence properties of supercontinuum (SC) generation in fibers are crucial in many applications. It is challenging to achieve SC spectra in the combination of the properties since special dispersion profiles are required, especially when the pump pulses with duration over 100 fs are employed. We propose an all-solid microstructured fiber composed only of hexagonal glass elements. The optimized fiber possesses an ultraflat all-normal dispersion profile covering a wide wavelength interval of approximately 1.55 μm. An SC spectrum spanning from 1030 to 2030 nm (corresponding to nearly one octave) with flatness <3 dB is numerically generated in the fiber with 200 fs pump pulses at 1.55 μm. The results indicate that the broadband ultraflat SC sources can be all-fiber and miniaturized due to commercially achievable 200-fs fiber lasers. Moreover, the SC pulses feature high coherence and a single pulse in the time domain, which can be compressed to 13.9-fs pulses with high quality even for simple linear chirp compensation. The Fourier-limited pulse duration of the spectrum is 2.16 fs, corresponding to only 0.42 optical cycles.

Enhancement of stimulated emission by a metallic optofluidic resonator

Xianfeng Chen, Bei Jiang, and Hailang Dai

Doc ID: 318922 Received 04 Jan 2018; Accepted 08 Apr 2018; Posted 12 Apr 2018  View: PDF

Abstract: Stimulated emission can be controlled by material molecular energy band and intensity of pump laser, which can provide some of population inversion and promote ground electron transition, respectively. We use a metallic optofluidic resonator to enhance stimulated emission intensity. The quality factor Q and the spontaneous emission coupling factor β of the metallic optofluidic resonator are discussed in detail to explain the enhancement mechanism. Experimental data demonstrate that the operated emission from Rhodamin 6G solution can be observed due to the enhancement of stimulated emission from the optofluidic resonator.

Active /Passive Q-switching operation of 2μm Tm,Ho:YAP laser with acousto-optical Q-switch / MoS2 saturable absorber mirror

Linjun Li, xining yang, Long Zhou, Wenqiang Xie, Yunlong Wang, yingjie shen, Yuqiang Yang, Wenlong Yang, Wei Wang, Zhiwei Lv, Xiaoming Duan, and minghua Chen

Doc ID: 324784 Received 26 Feb 2018; Accepted 06 Apr 2018; Posted 06 Apr 2018  View: PDF

Abstract: Active /passive Q-switching operation of 2 μm a-cut Tm,Ho:YAP laser was experimentally demonstrated with an acousto-optical (AO) Q-switch / MoS2 saturable absorber (SA) mirror. The active Q-switch laser was operated, for the first time, with an average output power of 12.3 W and a maximum pulse energy of 10.3 mJ. The passive Q-switch laser was also the first acquired with an average output power of 3.3 W and per pulse energy of .31 μJ, and the beam quality factors of M_x^2=1.06 and M_y^2=1.06 were measured at the average output power of 2 W.

Backcoupling manipulation in silicon ring resonators

ang li and Wim Bogaerts

Doc ID: 324866 Received 26 Feb 2018; Accepted 05 Apr 2018; Posted 06 Apr 2018  View: PDF

Abstract: In this paper we theoretically propose and experimentally demonstrate the manipulation of a novel degree of freedom in ring resonator, which is the coupling from the clockwise input to the counterclockwise propagating mode (and vice versa). We name this mechanism backcoupling, in contrast with the normal forward coupling of a directional coupler. It is well known that internal reflections will cause peak splitting to a ring resonator. Our previous research demonstrated that the peak asymmetry will be strongly influenced by the backcoupling. Thus it's worthy manipulating the backcoupling in order to get full control of a split resonance for the benefit of various resonance splitting based applications. While it's very difficult to directly manipulate the backcoupling of a conventional directional coupler, here we design a circuit explicitly for manipulating the backcoupling. It can be potentially developed for applications like single sideband filter, resonance splitting elimination, Fano resonance and ultra high Q and Finesse.

Electric field tunable strong transverse light current from nanoparticles embedded in liquid crystal

Xiangdong Zhang and Jinhua Li

Doc ID: 325675 Received 08 Mar 2018; Accepted 05 Apr 2018; Posted 06 Apr 2018  View: PDF

Abstract: We present an exact solution to the problem of electromagnetic scattering by nanosphere clusters embedded in a liquid crystal cell based on the Mie theory. The dependence of the scattering property on the structure parameters has been investigated in detail. It is shown that strong transverse light currents in the optical frequency can be obtained from these complex structures. Furthermore, we find that sign reversal of the transverse light current can also be realized by changing frequency and voltage. The physical origins for these phenomena have been analyzed. The transverse light current for subwavelength nanoscale dimensions is of practical significance. Thus, the applications of these phenomena to optical devices are anticipated.

Optical vortex copier and regenerator in the Fourier domain

Xiaodong Qiu, Fangshu Li, Haigang Liu, Xianfeng Chen, and Lixiang Chen

Doc ID: 319681 Received 12 Jan 2018; Accepted 05 Apr 2018; Posted 12 Apr 2018  View: PDF

Abstract: The generation and manipulation of optical vortices are of fundamental importance in a variety of promising applications. Here we develop a nonlinear optical paradigm to implement self- and cross-convolution of optical vortex arrays, demonstrating the features of vortex copier and regenerator. We use a phase-only spatial light modulator (SLM) to prepare the 1064nm invisible fundamental light to carry special optical vortex arrays, and use a Potassium titanyl phosphate (KTP) crystal to perform type II second harmonic generation (SHG) in the Fourier domain to achieve 532nm visible structured vortices. Based on pure cross-convolution, we succeed in copying arbitrary-order single vortices as well as their superposition states onto a prearranged array of fundamental Gaussian spots. Also, based on simultaneous effect of self- and cross-convolutions, we can expand the initial vortex lattices to regenerate more vortices carrying various higher topological charges. Our present method of realizing optical vortex copier and regenerator could find direct applications in optical manipulation, optical imaging, optical communication, and quantum information processing with structured vortex arrays.

Robust cavity soliton formation with hybrid dispersion

Jing Wang, Yuhao Guo, Henan Liu, Lionel Kimerling, Jurgen Michel, Anuradha Agarwal, Guifang Li, and Lin Zhang

Doc ID: 320234 Received 22 Jan 2018; Accepted 03 Apr 2018; Posted 18 Apr 2018  View: PDF

Abstract: Microresonator-based Kerr frequency combs have attracted a great deal of attention in recent years, in which mode-locking of the generated combs is associated with bright or dark cavity soliton formation. In this paper, we show that, different from solitons propagating along a waveguide, cavity solitons can be robustly formed under a unique dispersion profile with four zero-dispersion wavelengths. More importantly, such a dispersion profile exhibits much smaller average dispersion, thus making it possible to greatly reduce the pump power by 5 to 6 times.

Spatially-resolved measurement of plasmon dispersion using Fourier-plane spectral imaging

Amir Ohad, Katherine Akulov, Eran Granot, Uri Rossman, Fernando Patolsky, and Tal Schwartz

Doc ID: 308772 Received 10 Oct 2017; Accepted 02 Apr 2018; Posted 04 Apr 2018  View: PDF

Abstract: We show that Fourier-plane imaging in conjunction with the Kretschmann-Raether configuration can be used for measuring polariton dispersion with spatial discrimination of the sample, over the whole visible spectral range. We demonstrate the functionality of our design on several architectures, including plasmonic waveguides, and show that our new design enables the measurement of plasmonic dispersion curves of structures as small as 3μm in a single shot.

Ultra-compact broadband polarization beam splitter with strong expansibility

Jie Huang, Yang Junbo, Dingbo Chen, xin He, Yunxin Han, JingJing Zhang, and Zhaojian Zhang

Doc ID: 317901 Received 18 Dec 2017; Accepted 02 Apr 2018; Posted 04 Apr 2018  View: PDF

Abstract: Based on the traditional directional coupler, we proposed a new scheme to design on-chip polarization beam splitters by using inverse design method. In our scheme, the coupling area of the designed devices are only 0.48 μm × 6.4 μm. By manipulating the refractive index of the coupling region, the devices can work in C-band, L-band, O-band or any other communication bands. Different from conventional design methods, which need to adjust the design parameters artificially, if the initial conditions are determined, the proposed scheme can automatically design devices according to requirements. The simulation results show that the insertion losses of the designed polarization beam splitters can be less than 0.4 dB (0.35 dB) for TE (TM) at the wavelength of 1310 nm, 1550 nm and 1600 nm, and the extinction ratios are larger than 19.9 dB for TE and TM mode at all three wavelengths. Besides, the extinction ratios of both polarization states are more than 14.5 dB within the wavelength range of 1286 nm-1364 nm, 1497 nm-1568 nm and 1553 nm-1634 nm. At the same time, the insertion losses are smaller than 0.46 dB.

Generation rate scaling: the quality factor optimization of micro-ring resonator for photon-pair sources

Kai Guo, Xiaodong Shi, Xiaolin Wang, Junbo Yang, Yunhong Ding, Haiyan Ou, and Yijun Zhao

Doc ID: 320070 Received 17 Jan 2018; Accepted 29 Mar 2018; Posted 04 Apr 2018  View: PDF

Abstract: To achieve photon-pair generation scaling, we optimize the quality factor of micro-ring resonators for efficient continuous-wave-pumped spontaneous four-wave mixing. Numerical studies indicate that high intrinsic quality factor makes possible high pair rate and pair brightness, of which the maximums take place in the over-coupling and critical-coupling conditions, respectively. We fabricate six all-pass type micro-ring resonator samples on a silicon-on-insulator chip involving gap width as the only degree of freedom. The pair rate, pair brightness and coincidence rate of all the samples are characterized, which are then compared to the modified simulations by taking the detector saturation and nonlinear loss into account. Being experimentally validated for the first time to our best knowledge, this work explicitly demonstrates that reducing the round-trip loss in ring cavity and designing the corresponding optimized gap width are more effective to generate high-rate or high-brightness photon pairs than the conventional strategy of simply increasing the quality factor.

Numerical modeling of Linear Photonic System for Accurate and Efficient Time-Domain Simulations

Yinghao Ye, Domenico Spina, Yufei Xing, Wim Bogaerts, and Tom Dhaene

Doc ID: 312773 Received 21 Nov 2017; Accepted 29 Mar 2018; Posted 30 Mar 2018  View: PDF

Abstract: In this paper, a novel modeling and simulation method for general linear, time-invariant, passive photonic devices and circuits is proposed. This technique, starting from the scattering parameters of the photonic system under study, builds a lowpass equivalent state-space model which splits the optical carrier frequency and operates at baseband, thereby significantly reducing the modeling and simulation complexity without losing accuracy. Indeed, it is possible to analytically reconstruct the port signals of the photonic system under study starting from the time-domain simulation of the corresponding lowpass equivalent model. However, such equivalent models are complex-valued systems and, in this scenario, the conventional passivity constraints are not applicable anymore. Hence, the passivity constraints for scattering parameters and state-space models of lowpass equivalent systems are presented, which are essential for time-domain simulations. Three suitable examples demonstrate the feasibility, accuracy and efficiency of the proposed method.

Extraordinary characteristics for 1D PT-symmetric periodic ring optical waveguide networks

Yan Zhi, Xiangbo Yang, Jiaye Wu, Shiping Du, Peichao Cao, Dongmei Deng, and Chengyi Liu

Doc ID: 318894 Received 19 Jan 2018; Accepted 29 Mar 2018; Posted 30 Mar 2018  View: PDF

Abstract: In this paper, we design a one-dimensional (1D) PT-symmetric periodic ring optical waveguide network (PTSPROWN) and investigate its extraordinary optical characteristics. It is found that quite different from traditional vacuum/dielectric optical waveguide networks, 1D PTSPROWN can not produce photonic ordinary propagation mode (OPM), but can generate simultaneously two kinds of photonic non-propagation modes, attenuation propagation mode (APM) and gain propagation mode (GPM). It creates neither passband nor stopband and then possesses no photonic band structure. This makes 1D PTSPROWN possess richer spontaneous PT-symmetric breaking points and appear interesting extremum spontaneous PT-symmetric breaking points, where electromagnetic (EM) waves can create ultrastrong extraordinary transmission, reflection, and localization and the maximum can arrive at 6.6556*10^{12} and are more than seven orders of magnitude larger than the results reported previously. 1D PTSPROWN may possess potential in designing high efficiency optical energy saver devices, optical amplifiers, optical switches with ultrahigh monochromatity, and so on.

Ultrafast optical nonlinearity of blue-emitting perovskite nanocrystals

Junzi Li, Can Ren, Xin Qiu, Xiaodong Lin, Rui Chen, Cheng Yin, and Tingchao He

Doc ID: 318626 Received 10 Jan 2018; Accepted 28 Mar 2018; Posted 28 Mar 2018  View: PDF

Abstract: Perovskite nanocrystals (NCs) have strong nonlinear optical responses with a number of potential applications, ranging from upconverted blue-lasing to the tagging of specific cellular components in multicolor fluorescence microscopy. Here, we determine the one-photon linear absorption cross-section of two kinds of blue-emitting perovskite NCs, i.e., CsPbCl3 and CsPb(Cl0.53Br0.47)3, by utilizing femtosecond transient absorption spectroscopy. The wavelength dependent nonlinear refraction and two-photon absorption have been measured at wavelengths from 620 to 720 nm by performing Z-scan measurements. The nonlinear optical responses of CsPb(Cl0.53Br0.47)3 are much more pronounced than that of CsPbCl3 due to the larger structural destabilization of the former.

Passively Q-switched erbium doped fiber laser using gold nanostars based saturable absorber

Zhe Kang, Mingyi Liu, Li Zhenwei, Si Li, Zhixu Jia, Cheng-Zhi Liu, WP Qin, and Guanshi Qin

Doc ID: 318015 Received 19 Dec 2017; Accepted 25 Mar 2018; Posted 28 Mar 2018  View: PDF

Abstract: In this letter, we propose and demonstrate an all-fiber passively Q-switched erbium doped fiber laser (EDFL) by using gold nanostars (GNSs) as saturable absorber (SA) for the first time, to the best of our knowledge. In comparison with other gold nanomorphologies, GNSs have multiple localized surface plasmon resonances, which means that it can be used for construct wideband ultrafast pulse laser. By inserting the GNSs SA into an EDFL cavity pumped by a 980 nm laser diode, stable passively Q-switched laser at 1564.5 nm was achieved for a threshold pump power of 40 mW. By gradually increasing the pump power from 40 mW to 120 mW, the pulse duration decreases from 12.8 μs to 5.3 μs and the repetition rate increases from 10 kHz to 17 kHz. Our results indicate that the GNSs are a promising SA for constructing pulse lasers

High energy soliton pulses generation by MSDgrownMoTe2 saturable absorber

Jintao Wang, Zike Jiang, hao chen, Jiarong Li, Jinde Yin, Jinzhang Wang, Tingchao He, Peiguang Yan, and Shuangchen Ruan

Doc ID: 320274 Received 22 Jan 2018; Accepted 22 Mar 2018; Posted 23 Mar 2018  View: PDF

Abstract: The pulse energy in the ultrafast soliton fiber laser oscillators is usually limited by the well-known wave-breaking phenomenon owing to the absence of desirable real saturable absorber (SA) with high power tolerance and large modulation depth. Here, we reported a type of microfiber-based MoTe2 SA fabricated by the magnetron-sputtering deposition (MSD) method. High energy wave-breaking free soliton pulses were generated with pulse duration / pulse energy / average output power of 229 fs / 2.14 nJ / 57 mW at 1.5 μm regime and 1.3 ps / 13.8 nJ / 212 mW at 2 μm regime, respectively. To our knowledge, the generated soliton pulses at 1.5 μm had the shortest pulse duration and the highest output power among the reported erbium-doped fiber lasers mode locked by transition metal dichalcogenides (TMDs). Moreover, this was the first demonstration of MoTe2-based SA in fiber lasers at 2 μm regime, and the pulse energy / output power are the highest in the reported thulium-doped fiber lasers mode-locked by two-dimensional (2D) materials. Our results suggested that microfiber based MoTe2 SA could be used as an excellent photonic device for ultrafast pulse generation, and MSD technique opens a promising route to produce high-performance SA with high power tolerance and large modulation depth, which is beneficial for high energy wave-breaking free pulse generation.

Wide-field in situ multiplexed Raman imaging with super-resolution

Houkai Chen, Wu Xiaojing, Yuquan Zhang, Yong Yang, Changjun Min, Siwei Zhu, Xiaocong Yuan, qiaoliang bao, and jing bu

Doc ID: 320120 Received 18 Jan 2018; Accepted 20 Mar 2018; Posted 23 Mar 2018  View: PDF

Abstract: Because of the fingerprint-like specificity of its characteristic spectrogram, Raman spectral imaging has been applied widely in various research areas. Using a combination of structured illumination with the surface enhanced Raman scattering (SERS) technique, wide-field Raman imaging is developed with a significant improvement in spatial resolution. As a result of the relatively narrow Raman characteristic peaks achieved here, optically encoded SERS nanoparticles can be used to perform multiplexed imaging. The results show excellent super-resolution wide-field multiplexed imaging performance. The developed technique has extraordinary potential for applications in biological imaging and other related fields.

Chirp control of fs-pulse scattering from drag-reducingsurface-relief gratings

Juliane Eggert, Bjorn Bourdon, Stefan Nolte, Jörg Rischmüller, and Mirco Imlau

Doc ID: 320238 Received 22 Jan 2018; Accepted 13 Mar 2018; Posted 14 Mar 2018  View: PDF

Abstract: The role of chirp on the light-matter interaction of femto- and picosecond laser pulses with functional structured surfaces is studied using drag reducing riblets as an example. The three-dimensional, periodic microstructure naturally gives rise to a mutual interplay of (i) reflection, (ii) scattering, and (iii) diffraction phenomena of incident coherent light. Furthermore, for femtosecond pulses, the structure induces (iv) an optical delay equivalent to a consecutive temporal delay of 0 fs in places of the pulse. These features enable to experimentally and numerically study the effect of tuning, both, pulse duration τ and spectral bandwidth Δω on the features of the wide-angle scattering pattern from the riblet structure. As a result, we discovered a significant break-down of fringes in the scattering pattern with decreasing pulse duration and/or increasing spectral bandwidth. This unique type of chirp control is straightforwardly explained and verified by numerical modeling considering the spectral and temporal interaction between different segments within the scattered, linearly chirped pulse andthe particular geometric features of the riblet structure. The visibility of the fringe pattern can be precisely adjusted, the off-state is achieved using τ < 0 fs or Δω > 2.85·10¹³ rad/s.

Single-Mode VCSEL for Pre-Emphasis PAM-4 transmission up to 64 Gbit/s over 100-300 m in OM4 MMF

Hsuan-Yun Kao, Cheng-Ting Tsai, Shan-Fong Leong, Chun-Yen Peng, Yu-Chieh Chi, Huai-Yung Wang, Hao-chung Kuo, Chao-Hsin Wu, Wood-Hi Cheng, and Gong-Ru Lin

Doc ID: 312994 Received 08 Nov 2017; Accepted 17 Dec 2017; Posted 22 Dec 2017  View: PDF

Abstract: A single-mode vertical cavity surface emitting laser (VCSEL) based data transmission is demonstrated, which enables 4-level pulse amplitude modulation (PAM-4) at 64 Gbit/s over 100-300 m in the OM4 multi-mode fiber (MMF). By optimizing the bias of the single-mode VCSEL with a differential resistance of 159 ohm the related electrical return loss of -5.7 dB is evaluated to provide an analog modulation bandwidth of 18.9 GHz. After pre-emphasizing waveform of the PAM-4 format, the PAM-4 data stream can be successfully delivered by the single-mode VCSEL at 64 Gbit/s under back-to-back and 100-m-long OM4 MMF conditions. Lengthening the transmission distance worsens the signal-to-noise ratio of PAM-4 data to the FEC criterion, as the waveform pre-emphasis of the PAM-4 data stream inevitably induces spectral power compensation from-low to high frequencies. Therefore, increasing the OM4 MMF distance from 200 to 300 m significantly reduces the peak-to-peak amplitude of data to suppress the SNR and reduce the transmission capacity from 52 to 48 Gbit/s.

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