Han Zhihang   Sun Cuiting   Jin Xiren   Jiang Hang   Yao Chong   Zhang Shuo   Liu Weiliang   Geng Tao   Peng Feng   Sun weimin   Yuan Libo  

      摘要 + ：(浏览：6次) | 此论文可免费阅读 (可能需要登录)

A torsion sensor based on the near-helical long period fiber grating (NH-LPFG) is fabricated by using a high frequency pulsed CO2 laser. Each groove of the NH-LPFG is spirally written in the four sides of a single mode fiber. The NH-LPFG has a helical periodic vertical index modulation. This is different from the screw-type index modulation of the common H-LPFGs fabricated in a twisted fiber. The torsion and temperature characteristics of the NH-LPFG are experimentally investigated. The temperature sensitivity is about 0.0668 nm/°C. The torsion sensitivity is 0.103 nm/(rad/m) and independent to the polarization state of incident light.

       PDF全文 (下载：2)        Chinese Optics Letters ，2018年第16卷第10期 pp.10      

Zhang Li   Li Fangye   Wang Shuai   Wang Qi   Luan Kairan   Chen Xi   liu xiuhuan   Qiu Lingying   Chen Zhanguo   Zhao Ji-Hong   Hou Lixin   Gao Yanjun   jia Gang  

      摘要 + ：(浏览：5次) | 此论文可免费阅读 (可能需要登录)

In this paper, we have demonstrated significant electric field induced (EFI) optical rectification (OR) effects existing in the surface layers of germanium (Ge), and measured the distributions of EFI OR signals along the normal directions of surface layers of Ge samples. Based on the experimental results, the ratios of the two effective second-order susceptibility componentsχ_zzz^((2eff))/χ_zxx^((2eff)) for Ge(001) , Ge(110) and Ge(111) surface layers can be estimated to be about 0.92, 0.91, and 1.07, respectively. The results indicated that the EFI OR can be used for analyzing the properties on surface layers of Ge, which has potential applications in Ge photonics and optoelectronics.

       PDF全文 (下载：3)        Chinese Optics Letters ，2018年第16卷第10期 pp.10      

zhou linjie   Wang Xinyi   Lu Liangjun   Chen Jianping  

      摘要 + ：(浏览：6次) | 此论文可免费阅读 (可能需要登录)

Optical delay lines (ODLs) are one of the key enabling components in photonic integrated circuits and systems. They are widely used in time-division multiplexing, optical signal synchronization and buffering, microwave signal processing, beam forming and steering etc. The development of integrated photonics pushes forward the miniaturization of ODLs, offering improved performances in terms of stability, tuning speed and power consumption. The integrated ODLs can be implemented using various structures, such as single or coupled resonators, gratings, photonic crystals, multi-paths switchable structures, recirculating loop structures. The delay tuning in ODLs is enabled by either changing the group refractive index of the waveguide or changing the length of the optical path. This paper reviews the recent development of integrated ODLs, with a focus on their abundant applications and flexible implementations. The challenges and potentials of each type of ODLs are pointed out.

       PDF全文 (下载：3)        Chinese Optics Letters ，2018年第16卷第10期 pp.10      

Liu Jiao   Liu Yang   Tang Xiaojun   Wang Chao  

      摘要 + ：(浏览：11次) | 此论文可免费阅读 (可能需要登录)

We demonstrate a high-efficiency and high-power quasi-three-level laser based on a trapezoidal composite slab architecture with a 270 μm-thick Yb-doping surface. The design of surface-doped slab architecture, temperature effects, laser oscillator model and laser oscillator experiments with surface-doped slab as laser host media have been presented. By theoretical calculation, the temperature rise in the surface-doped slab is only seventh of that is in the bulk doped slab at the same maximum pump power of 30 kW. Finally, in the laser oscillator experiments, the output energy of 21.6 J is obtained when the pump energy is 48 J with the repetition rate of 5 Hz and pulse width of 1 ms. The optical-optical efficiency is 45%.

       PDF全文 (下载：3)        Chinese Optics Letters ，2018年第16卷第10期 pp.10      

xu longbo   Liu Shijie   Zhu Ri Hong   Zhou You   chen jie  

      摘要 + ：(浏览：3次) | 此论文可免费阅读 (可能需要登录)

In this paper, a test method based on oblique incidence is practically implemented in the interferometric measurement process. Three sets of wavefront data are achieved through cavity interference measurement with a Fizeau interferometer and one oblique incidence measurement. An iterative algorithm is applied to retrieve the matrix of transmission flatness and reference flatness. The new method can not only calibrate the reference flat error of interferometer, but also provide the absolute measurement method for high precision optical components applied in high power laser systems.

       PDF全文 (下载：2)        Chinese Optics Letters ，2018年第16卷第10期 pp.10      

Zhao Zixin   Zhuang Yiying   Xiao Zhaoxian   Zhang Hangying   Fan Chen   Geng Hehui   Zhao Hong  

      摘要 + ：(浏览：23次) | 此论文可免费阅读 (可能需要登录)

The phase modulation characteristics of a reflective liquid crystal spatial light modulator (LC-SLM) under oblique incidence are studied by using our proposed self-interference method. The experimental setup of the method is very simple and has good robustness to mechanical vibrations. By changing the gray value of the combined grayscale loaded on the LC-SLM, different sheared fringe patterns, generated by the interference between the constant phase-modulated beam and the +1 order diffracted beam of the blazed grating, can be obtained. The amount of phase modulation of the LC-SLM is obtained by subtracting the phase of the two side lobes in frequency domain. By turning the turntable where the SLM is mounted, the phase modulation characteristics at different incident angles can be measured. The experimental results show that the phase modulation curves do not change significantly with the small angle. When the angle is large (i.e. larger than 10 degrees), the phase modulation curves become different especially for the high gray levels. With the increase of the incident angle, phase modulation depth is reduced. The results indicate that the incident angle plays an important role in the performance of the phase modulation of an LC-SLM.

       PDF全文 (下载：10)        Chinese Optics Letters ，2018年第16卷第9期 pp.09      

zhang hao   yao lei   Pang Yuyan   Xia Jun  

      摘要 + ：(浏览：22次) | 此论文可免费阅读 (可能需要登录)

We propose theoretically and verify experimentally a compact optical configuration to directly generate arbitrary vector vortex beams on hybrid-order Poincaré sphere with a good flexibility and a high efficiency based on a reflective phase-only liquid crystal spatial light modulator (LC-SLM). The conversion system, consisting of a LC-SLM and a quarter-wave plate, can be considered as a flexible dielectric metasurface to simultaneously modulate inhomogeneous polarization and helical phase-front. This approach has some advantages, including a simple experimental setup, good flexibility, and high efficiency. Orthogonally polarized modes alignment and an explicit superposition existed in conventional method are not necessary in the proposed method, exhibiting potential applications in many advanced domains.

       PDF全文 (下载：7)        Chinese Optics Letters ，2018年第16卷第9期 pp.09      

Liu Dun   Wu Shibin   Yang Wei   Wang Lihua   Wu Fan   Fan Bin  

      摘要 + ：(浏览：22次) | 此论文可免费阅读 (可能需要登录)

The full aperture complex amplitude transmittance function of multi-level diffraction lens with mask-alignment errors was derived based on scalar diffraction theory. The point spread function(PSF) was calculated by Kirchhoff diffraction integral. It is found that the radius of Airy disk increases with the increase of the error in the direction of misalignment and the image center shift along the misalignment. A 4-level diffractive lens with a diameter of 80 mm was fabricated and the PSF and its diffraction efficiency of +1 order were calculated and measured. The distribution of PSF is consistent with the calculated results and the tested diffraction efficiency is slightly smaller than calculated value, the relative error is 5.71%.

       PDF全文 (下载：4)        Chinese Optics Letters ，2018年第16卷第9期 pp.09      

Bian Yayan   Liu Yongji   Jiang Lai  

      摘要 + ：(浏览：22次) | 此论文可免费阅读 (可能需要登录)

A double-zone aspheric diffractive intraocular lens (IOL) was designed and manufactured aiming to regain a continuous range of clear vision for pseudophakic presbyopia. After obtaining the IOL structure parameters through optimization based on an aphakic model eye, its imaging performances were analyzed in the model eye. The modulation transfer function at 50 cycles/mm remained above 0.29 within ± 5° field of view for object distance ranging from 6 m to 0.66 m. In addition, the imaging qualities are robust for pupil changes, polychromatic light and different corneal asphericities. The manufactured IOL exhibits the ability to extend depth of focus.

       PDF全文 (下载：4)        Chinese Optics Letters ，2018年第16卷第9期 pp.09      

Lyapin Andrey   Gushchin Sergey   Ermakov Alexander   Kuznetsov Sergey   Ryabochkina Polina   Proydakova Vera   Voronov Valerii   Fedorov Pavel   Chernov Maxim  

      摘要 + ：(浏览：24次) | 此论文可免费阅读 (可能需要登录)

Mechanisms of upconversion luminescence of SrF₂:Er phosphors corresponding to the ⁴G_11/2→⁴I_15/2, ²H_9/2→⁴I_15/2, ⁴F_5/2→⁴I_15/2, ⁴F_7/2→⁴I_15/2, ²H_11/2→⁴I_15/2, ⁴S_3/2→⁴I_15/2, ⁴F_9/2→⁴I_15/2 and ⁴I_9/2→⁴I_15/2 transitions upon excitation of the ⁴I_11/2 level of Er³⁺ ions were investigated. Energy transfer upconversion processes are responsible for the populating of the ²H_9/2, ²H_11/2, ⁴S_3/2, ⁴F_9/2 levels. Cooperative process is the dominant mechanism of luminescence from ⁴S_3/2 and ⁴F_9/2 levels for SrF₂:Er with high concentrations of Er³⁺ ions. The upconversion luminescence from ⁴G_11/2 and ⁴F_5/2 is explained by excited-state absorption. Cross-relaxation processes take part in the population of ⁴F_9/2 and ⁴I_9/2 levels. For quantifying material performance the Er³⁺-concentration-dependent of upconversion luminescence and absolute quantum yields of SrF₂:Er were studied. The most intensive visible luminescence was obtained for SrF₂:Er (14.2%). Maximum quantum yield was achieved 0.28% for SrF₂:Er (14.2%).

       PDF全文 (下载：2)        Chinese Optics Letters ，2018年第16卷第9期 pp.09      

Lin Kai   Jia Xin-Hong   Ma Huiliang   Xu Cong   Zhang Xuan   Ao Lei  

      摘要 + ：(浏览：40次) | 此论文可免费阅读 (可能需要登录)

The impacts of Brillouin pump depletion and nonlinear amplification in coded long-range Brillouin optical time-domain analysis (BOTDA) based on distributed Brillouin amplification (DBA) were studied. The error of Brillouin frequency shift (BFS) due to Brillouin pump depletion was compared for DBA-BOTDA using non-cyclic and cyclic coding. For non-cyclic coding, significant over- and under-shoots of BFS were found at the range with larger BFS variation, such as hot-spot. The impact of Brillouin pump depletion can be reduced considerably by cyclic coding. Furthermore, to compensate the BFS error due to nonlinear amplification, a simple and effective log linearization was proposed and demonstrated.

       PDF全文 (下载：15)        Chinese Optics Letters ，2018年第16卷第9期 pp.09      

He Xi   Liu Cheng   Zhu Jianqiang  

      摘要 + ：(浏览：25次) | 此论文可免费阅读 (可能需要登录)

We propose a novel on-line beam diagnostic method based on beam splitting single-shot phase retrieval. The incident beam to be measured is diffracted into many replicas by a Dammann grating and then propagate through a weakly scattering phase plate with known structure, the exiting beams propagate along their original direction and form an array of diffraction pattern on the detector plane. By applying the intensity of diffraction patterns into an iterative algorithm and calculating between grating plane, weakly scattering plane, and the detector plane, the complex field of incident beam can be reconstructed rapidly, the feasibility of this method is verified experimentally with wavelength of 1053nm and 632.8nm.

       PDF全文 (下载：9)        Chinese Optics Letters ，2018年第16卷第9期 pp.09      

Guo Xin   Ding Jinbin   Zhou Yi   Wang Yu  

      摘要 + ：(浏览：24次) | 此论文可免费阅读 (可能需要登录)

The ablation of Sintered Silicon Carbide Ceramics by ArF excimer laser were studied. Three zones are generated: the ablation zone presented molten morphology and composed by Si and C phase; the condensation zone formed by vaporized SiC; the oxidation zone showed the characteristics of thermal oxidation. The ablation depth and oxidation range increase linearly with fluence and pulses within 0.5-4J/cm2, but the normalized ablation efficiency is constant (3.60±0.60). The theoretical photochemical ablation depth supplies 25% of the total depth at 1J/cm2 but decreases to 16% at 4J/cm2. The ablation is dominated by photothermal effect and conforms to thermal evaporation mechanism.

       PDF全文 (下载：4)        Chinese Optics Letters ，2018年第16卷第9期 pp.09      

Liu kai   Fan Huize   Huang Yongqing   Duan Xiaofeng   Wei Qi   Wang Qi   Ren Xiaomin   Cai Shiwei  

      摘要 + ：(浏览：21次) | 此论文可免费阅读 (可能需要登录)

In this paper, a pair of integrated optoelectronic transceiving chips are proposed. They are constructed by integrating a vertical cavity surface emitting laser (VCSEL) unit above a PIN photodetector (PIN-PD) unit. One of the transceiving chips emits light at the wavelength of 848.1nm, with a threshold current of 0.8mA and a slop efficiency of 0.81W/A. It receives light between 801 nm and 814 nm, with a quantum efficiency of higher than 70%. On its counterpart, the other one of the transceiving chips emits light at the wavelength of 805.3nm, with a threshold current of 1.1mA and a slop efficiency of 0.86W/A. It receives light between 838 nm and 855 nm, with a quantum efficiency of higher than 70%. So that the proposed pair of integrated optoelectronic transceiving chips can work full-duplex with each other. They can be applied for single fiber bidirectional optical interconnects.

       PDF全文 (下载：3)        Chinese Optics Letters ，2018年第16卷第9期 pp.09      

Wang Kejia   Gu Xinyang   Zhang Zhenwei   Yang Zhengang   Liu Jinsong   Wang Shenglie  

      摘要 + ：(浏览：25次) | 此论文可免费阅读 (可能需要登录)

Previous research shows that few-cycle laser (FCL) pulses with low energy and without a bias field can be used to coherently detect terahertz (THz) pulses. As we know, it is very difficult to stabilize the carrier envelop phase (CEP) of FCL pulses, i.e. there are some random fluctuations for the CEP. Here we theoretically investigate the influence of such instability on the accuracy of THz detection. Our results show that although there is an optimum CEP for THz detection, the fluctuations of CEP will lead to terrible thorns on the detected THz waveform. In order to solve this problem, we propose an approach via using two few-cycle laser pulses with opposite CEPs, i.e. their CEPs are differed by <i>π</i> .

       PDF全文 (下载：5)        Chinese Optics Letters ，2018年第16卷第9期 pp.09      

Sulaiman Abdul Hadi   Abdul kadir Muhammad Zamzuri   YUSOFF NELIDYA   Cholan Noran Azizan   Abdullah Fairuz   Abas Ahmad Fauzi   Alresheedi Mohammed Thamer   Adzir Mahdi Mohd  

      摘要 + ：(浏览：25次) | 此论文可免费阅读 (可能需要登录)

We demonstrate a broad bandwidth multiwavelength laser based on a bidirectional Lyot filter and semiconductor optical amplifier with a mechanism of intensity dependent loss as the flatness agent. A wide bandwidth of multiwavelength spectrum of 32.9 nm within 5 dB uniformity is obtained under optimized polarization parameters. For this case, the number of generated lasing lines is 329 with a fixed wavelength separation of 0.1 nm. The power stability of this multiwavelength laser is less than 1.35 dB within 200 minutes time frame. This shows that the bidirectional Lyot filter provides an alternative option for multiwavelength generation in laser systems.

       PDF全文 (下载：7)        Chinese Optics Letters ，2018年第16卷第9期 pp.09      

zhou daibing   Zhao Lingjuan  

      摘要 + ：(浏览：29次) | 此论文可免费阅读 (可能需要登录)

We report 20 Gb/s transmission of 4-level pulse amplitude modulation (PAM) signal using a directly modulated tunable distributed Bragg reflector (DBR) laser, Transmission distance over 20 km was achieved without using optical amplifiers and optical dispersion compensation modules. A wavelength tuning range of 11.5 nm and the 3-dB bandwidth greater than 10 GHz over the entire wavelength tuning range was obtained.

       PDF全文 (下载：11)        Chinese Optics Letters ，2018年第16卷第9期 pp.09      

Ma Lina   Chen Yu   Hu Zhengliang   Huang Jinxing   Wang Jun   Li Shiqing  

      摘要 + ：(浏览：28次) | 此论文可免费阅读 (可能需要登录)

We presented an interferometric phase shift fiber Bragg grating (PS-FBG) sensor, which inherited the advantages Of FBG sensors and at the same time, the greatly reduced full-width-half-maximum (FWHM) bandwidth brought longer coherent length, higher sensitivity and lower phase noise. Experiments show that at least 7 dB reduction of phase noise can be achieved compared to FBG sensors interrogated by interferometer with the same optical path difference (OPD).

       PDF全文 (下载：6)        Chinese Optics Letters ，2018年第16卷第9期 pp.09      

Samavati Zahra   SAMAVATI ALIREZA   Ismail Ahmad Fauzi   A. Rahman Mukhlis   Othman M. H. D.  

      摘要 + ：(浏览：36次) | 此论文可免费阅读 (可能需要登录)

Miniature optical fiber sensors with thin films as sensitive elements could open new fields for optical fiber sensor applications. Thin films work as sensitive elements and transducer to get response and feedback from environments, in which optical fibers act as signal carrier. A novel Ag coated intensity modulated optical fiber sensors based on refractive index changes using IR and UV-Vis light sources are proposed. The sensor with IR light source has more sensitivity compare to UV-Vis source. When the refractive index enhanced to 1.38, the normalized intensity of IR and UV-Vis light diminish to 0.2 and 0.8 respectively.

       PDF全文 (下载：9)        Chinese Optics Letters ，2018年第16卷第9期 pp.09      

Shi Junheng   Patera Giuseppe   Gui Youzhen   Kolobov Mikhail   Horoshko Dmitri   Han Shensheng  

      摘要 + ：(浏览：28次) | 此论文可免费阅读 (可能需要登录)

The point-spread function of an optical system determines its optical resolution for both spatial and temporal imaging. For spatial imaging it is given by a Fourier transform of the pupil function of the system. For temporal imaging based on nonlinear optical processes, such as sum-frequency generation or four-wave mixing, the point-spread function is related to the waveform of the pump wave by a nonlinear transformation. We compare the point-spread functions of three temporal imaging schemes: sum-frequency generation, co-propagating four-wave mixing, and counter-propagating four-wave mixing, and demonstrate that the last scheme provides the best temporal resolution. Our results is valid for both quantum and classical temporal imaging.

       PDF全文 (下载：12)        Chinese Optics Letters ，2018年第16卷第9期 pp.09