Accepted papers to appear in an upcoming issue
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Silicon Photonic Integration for Mid-infrared
Ting Hu, Bowei Dong, Xianshu Luo, Tsung-Yang Liow, Junfeng Song, Chengkuo Lee, and Guo-Qiang Lo
Doc ID: 297458 Received 05 Jun 2017; Accepted 12 Jul 2017; Posted 12 Jul 2017 View: PDF
Abstract: Silicon photonic integrated circuits for tele-communication and data-center application have been well studied in the past decade and now most of the efforts have been progressing towards commercialization. Scaling up the silicon-on-insulator (SOI) based device dimensions in order to extend the operation wavelength to mid-infrared (MIR) range are starting to attract research interests recently, owing to their host of potential applications in lab-on-chip sensors, thermal imaging, free-space communications, and many more. Other material systems and technology platforms, including silicon-on-silicon nitride (SOSN), Germanium-on-Silicon (GOS), Germanium-on-SOI (GOI), Germanium-on-silicon nitride (GOSN), sapphire-on-silicon (SOS), SiGe alloy-on-Si (SGOS), and aluminum nitride-on-insulator (ANOI) are explored as well in order to realize low loss waveguide devices for different MIR wavelengths. In this paper, we will comprehensively review silicon photonics for MIR applications, with regard to the state-of-the-art achievements from various device demonstrations in different material platforms by various groups. We will then introduce in detail of our institute’s research and development efforts on the MIR photonic platforms as one case study. Meanwhile, we will discuss the integration schemes along with remaining challenges in devices (e.g., light source) and integration. Few application-oriented examples will be examined to illustrate the issues needing critical solution towards the final production path (e.g., gas sensors). Finally, we will provide our assessment of the outlook of potential future research topics and engineering challenges along with opportunities.
Performance analysis of ghost imaging lidar in background lightenvironment
chenjin Deng, Long Pan, Chenglong Wang, Xin Gao, Wenlin Gong, and Shensheng Han
Doc ID: 297457 Received 08 Jun 2017; Accepted 10 Jul 2017; Posted 20 Jul 2017 View: PDF
Abstract: The effect of background light on the imaging quality of three typical ghost imaging (GI) lidar system (namely narrow pulsed GI lidar, heterodyne GI lidar, and pulse-compression GI lidar via coherent detection) is investigated. By computing the signal-to-noise ratio (SNR) of fluctuation-correlation GI, our analytical results, which are backed up by numerical simulations, demonstrate that pulse-compression GI lidar via coherent detection has the strongest capacity against background light, whereas the reconstruction quality of narrow pulsed GI lidar is the most vulnerable to background light. The relationship between the peak signal-to-noise ratio of reconstruction image and σ (namely the signal power to background power ratio) for above three GI lidar systems, which accords with the curve of SNR-σ, is also presented.
Q-switching of waveguide laser based on graphene/WS2 van der Waals heterostructure
Ziqi Li, Chen Cheng, Ningning Dong, Carolina Romero, Qingming Lu, Jun Wang, Javier Vazquez de Aldana, Yang Tan, and Feng Chen
Doc ID: 297054 Received 02 Jun 2017; Accepted 10 Jul 2017; Posted 12 Jul 2017 View: PDF
Abstract: We report on the operation of passively Q-switched waveguide lasers at 1μm wavelength based on a graphene/WS2 heterostructure as a saturable absorber (SA). The gain medium is a crystalline Nd:YVO4 cladding waveguide produced by femtosecond laser writing. The nanosecond waveguide laser operation at 1064 nm has been realized with the maximum average output power of 275 mW and slope efficiency of 37%. In comparison to the systems based on single WS2 or graphene SA, the lasing Q-switched by graphene/WS2 heterostructure SA possesses advantages of higher pulse energy and enhanced slope efficiency, indicating the promising applications of van der Waals heterostructures for ultrafast photonic devices.
All-fiber acousto-optic modulator based on cladding-etched optical fiber for active mode-locking
Jihwan Kim, Joonhoi Koo, and Ju Han Lee
Doc ID: 295568 Received 09 May 2017; Accepted 09 Jul 2017; Posted 10 Jul 2017 View: PDF
Abstract: An all-fiber acousto-optic modulator (AOM) that features a compact structure and a low-driving voltage is experimentally demonstrated for the active mode-locking of a fiber laser. The proposed AOM is based on the short length of the cladding-etched fiber, the ends of which are fixed on a slide glass. On top of the cladding-etched fiber, a piezoelectric transducer (PZT) was overlaid. A chemical wet-etching technique that is based on a mixed solution of NH4F and (NH4)2SO4, was used to reduce the fiber diameter down to ~ 25 μm, and the length of the etched section is only 0.5 cm. The fabricated device exhibited a modulation depth of 73.10 % at an acoustic frequency of 918.9 kHz and a peak-to-peak electrical voltage of 10 V, while a laser beam was coupled at 1560 nm. By using the prepared AOM within an erbium-doped-fiber (EDF) ring cavity, the mode-locked pulses with a temporal width of 2.66 ps were readily obtained at a repetition rate of 1.838 MHz.
Coupled quantum molecular cavity optomechanics with surfaceplasmon enhancement
Ka-Di Zhu and Liu Jian
Doc ID: 291179 Received 22 Mar 2017; Accepted 06 Jul 2017; Posted 07 Jul 2017 View: PDF
Abstract: Cavity optomechanics is applied to study the coupling behavior ofthe interacting molecules in surface plasmon systems driven by twocolor laser beams. Different from the traditional force-distance measurement,due to a resonant frequency shift or a peak splitting on probe spectrum, we have proposed a convenient method tomeasure the van der Waals force strength and interaction energy via nonlinear spectroscopy. The minimum force value can reach approximately 10^(-16)N,which is 4-5 orders of magnitude smaller than the widelyapplied Atomic Force Microscope(AFM). It is also shown that two adjacent molecules with similar chemical structuresand nearly equal vibrational frequencies can be distinguished easilyby the splitting of the transparency peak. Based on this coupled optomechanical system, we alsoconceptually design a tunable optical switch by van der Waals interaction. Our results will provide new approaches for theunderstanding of the complex and dynamic interactions in molecule-plasmon systems.
Impact of nanoparticle-induced scattering of azimuthally propagating mode on the resonance of whispering gallery microcavities
Junda Zhu, Ying Zhong, and Haitao Liu
Doc ID: 296662 Received 25 May 2017; Accepted 01 Jul 2017; Posted 06 Jul 2017 View: PDF
Abstract: Optical whispering gallery microcavities with high quality factors have shown great potential to achieve ultra-high sensitivity sensing up to single molecule or nanoparticle, which raises a huge demand on a deep theoretical insight into the crucial phenomena such as the mode shift, mode splitting and mode broadening in sensing experiments. Here we propose an intuitive model to analyze these phenomena from the viewpoint of the nanoparticle-induced multiple-scattering of azimuthally propagating mode (APM). The model unveils explicit relations between these phenomena and the phase change and energy loss of the APM when scattered at the nanoparticle, and well explains the observed polarization-dependent preservation of one resonance and the particle-dependent redshift or blueshift. The model indicates that the particle-induced coupling between the pair of unperturbed degenerate whispering gallery modes (WGMs) and the coupling between the WGMs and the free-space radiation modes, which are widely adopted in current theoretical formalisms, are realized via the reflection and scattering-induced free-space radiation of the APM, respectively, and additionally exhibits the contribution of cross coupling between the unperturbed WGMs and other different WGMs to forming the splitting resonant modes especially for large particles.
Blue-detuned optical atom trapping in a compact plasmonic structure
zhao chen, Fan Zhang, Qi Zhang, Juanjuan Ren, He Hao, Xue Duan, Pengfei Zhang, Tiancai Zhang, Ying Gu, and Qihuang Gong
Doc ID: 292922 Received 17 Apr 2017; Accepted 28 Jun 2017; Posted 21 Jul 2017 View: PDF
Abstract: We theoretically propose an array of nanoholes for neutral atoms trapping via the strong near-field interfacing in a compact plasmonic structure. A plasmon resonant field that is blue-detuned from the atomic resonance, not only forms a nanoscale-trap potential with a full width at half-maximum of 200 nm that are about ~370 nm away from the nanohole, but also greatly reduces the input optical power. The effective trap depth is more than 1 mK when the optical power of the trapping light is only about 0.5 mW, the calculated atom scattering rates is merely about 3.31 s-1, and a trap lifetime is about 800 s. In addition, the proposed periodic system can provide high uniformity of trap depths. This kind of plasmonic structure is easy to fabricate and integrate, and an array of such atom nanotraps could have important applications in manipulation of cold atom arrays and resonance fluorescence.
Experimental investigation of ghost imaging of reflective objects with different surface roughness
Suqin Nan, Yanfeng Bai, Xiaohui Shi, Qian Shen, Hengxing Li, Lijie Qu, and Xiquan Fu
Doc ID: 291390 Received 24 Mar 2017; Accepted 27 Jun 2017; Posted 27 Jun 2017 View: PDF
Abstract: We present the first (to our knowledge) experimental demonstration of ghost imaging of reflective objects with different surface roughness. The influence of the surface roughness, the transverse size of the test detector, and the refective angle on the signal-to-noise ratio (SNR) is analyzed by measuring the second-order correlation of light field based on the classical statistical optics. It is shown that the SNR decreases with an increment of the surface roughness and the detector’s transverse size or a decrease of the reflective angle. Additionally, the comparative studies between the rough object and the smooth one under the same conditions are also discussed.
Multiple resonant excitations of surface plasmonic in a graphene stratified slab by Otto configuration and their independent tuning
Jin Yao, Ying Chen, Longfang Ye, Na Liu, Guoxiong Cai, and Qing Huo Liu
Doc ID: 295192 Received 19 May 2017; Accepted 27 Jun 2017; Posted 27 Jun 2017 View: PDF
Abstract: The multiple resonant excitations of surface plasmonic in a graphene stratified slab are realized by Otto configuration at terahertz frequencies. The proposed graphene stratified slab consists of alternating dielectric layers and graphene sheets, and is sandwiched between a prism and another semi-infinite medium. Optical response as well as field distribution are determined by the transfer matrix method with surface current-density boundary condition. Multiple resonant excitations are emerged on the angular reflection spectrum, which are analyzed theoretically by phase matching condition. Furthermore, the influences by the system parameters are investigated. Among them, the Fermi levels can tune the corresponding resonances independently. The proposed concept can be engineered for promising applications, including angular selective or multiplex filters, multiple channel sensors, and directional energy delivering.
Optical Crosstalk Reduction in Quantum-Dot-Based Full-Color μLED Display by Lithographic-Fabricated Potoresist Mold
Lin Huang Yu, Chin Wei Sher, Dan-Hua Hsieh, Xin-Yin Chen, Huang-Ming Chen, Teng-Ming Chen, Kei May Lau, Chyong-Hua Chen, Chien-Chung Lin, and Hao-chung Kuo
Doc ID: 291611 Received 29 Mar 2017; Accepted 23 Jun 2017; Posted 26 Jun 2017 View: PDF
Abstract: In this study, the full-color emission RGB quantum dot (QD)-based μLED array with reduced optical crosstalk effect by photoresist mold has been demonstrated. The UV μLED array is used for efficient excitation source for the QDs. The aerosol jet technique provides narrow linewidth in micro meter scale for precise jet of QDs on the μLEDs. To reduce the optical crosstalk effect, simple lithography method and photo-resist is carried out to fabricate the mold, which consists the window for QDs jetting, and blocking wall for crosstalk reduction. The crosstalk effect of the well-confined QDs in the window is confirmed by the fluorescence microscope, which shows clear separation between QD pixels. The distributed Bragg reflector is covered on the μLED array and QDs jetted mold to further increase the reuse of UV light, and the enhanced light emission from QDs is 5 %, 32 % and % for blue, green and red QDs.
Enhanced magneto-optical Kerr effect and index sensitivity in Au/FexCo1-x magnetoplasmonic transducers
Haipeng Lu, liu chuan, Jun Qin, Chuangtang Wang, Yan Zhang, Longjiang Deng, and Lei Bi
Doc ID: 292686 Received 13 Apr 2017; Accepted 20 Jun 2017; Posted 21 Jun 2017 View: PDF
Abstract: Magnetoplasmonic sensors using noble metal and ferromagnetic metal multilayers are attractive candidates for ultrasensitive chemical and biomedical sensor applications. A variety of ferromagnetic metal thin films have been used for magnetoplasmonic device applications, yet the dependence of the sensor performance on the ferromagnetic metal materials is rarely studied. In this work, we report the study of enhanced magneto-optical Kerr effect and sensing performance in Au/FexCo1-x bilayer magnetoplasmonic (MOSPR) transducers. The optical constants of FexCo1-x (x=0, 0.3, 0.5, 0.7, 1) in a sputter-deposited Au/FexCo1-x device are characterized by the attenuated total internal reflection method. FexCo1-x thin films show different magneto-optical Kerr effect (MOKE) as a function of the chemical concentration, with the highest TMOKE signal observed in Fe0.7Co0.3. The index sensing performance is closely related to the material’s optical and magneto-optical constants. By studying the sensing performance in the parameter space of the Au/FexCo1-x bilayer thicknesses, the highest sensitivity is found to be 0.385 (theoretical) and 0.306 RIU-1 (experimental) in the Au/Fe0.7Co0.3 MOSPR devices. Our research highlights the influence of ferromagnetic material optical properties to the device sensitivity in the MOSPR transducers. The high sensitivity in Au/FexCo1-x MOSPR devices make these structures attractive candidates for chemical and biomedical sensing applications.