Germanium microsphere high-Q resonator

In this Letter, the fabrication and characterization of a microsphere resonator from the semiconductor germanium is demonstrated. Whispering gallery modes are excited in a 46 μm diameter germanium microsphere resonator using evanescent coupling from a tapered silica optical fiber with a waist diameter of 2 μm. Resonances with Q factors as high as 3.8×10(4) at wavelengths near 2 μm are observed. Because of their ultrahigh optical nonlinearities and extremely broad transparency window, germanium microsphere resonators offer the potential for optical processing devices, in particular at long wavelengths, such as around 2 μm.     

掺铒磷酸盐玻璃微球吸收光谱上的形貌共振

利用高温熔融冷却法制备了直径为82．4μm的掺铒磷酸盐玻璃微球，并利用熔融拉丝法制备了锥腰直径为2．3μm的熔锥光纤与其进行耦合，发现了掺铒玻璃微球吸收光谱中出现的等间距分布的滤波谱线。利用光学微球腔理论讨论了玻璃微球吸收光谱中的形貌共振现象，计算出该耦合系统的品质因数为1．31×10^4。利用Mie散射理论计算了谱线的吸收峰位置和峰间间距，计算结果与实验结果相符合。最后比较了两种峰间间距算法的优劣。     

Single-input spherical microbubble resonator

A single-input whispering gallery optical microbubble resonator is presented. Spherical microbubbles with diameters less than 100 μm, micrometer-sized wall thicknesses, and a single opening or input were fabricated by heating the tapered tip of a pressurized glass capillary using a CO(2) laser. Optical whispering gallery modes with Q factors of ～10(5) were obtained. The bubbles were filled with water and mode shifts of ～20 GHz were observed. Fano-type resonances were detected when the coupling optical fiber diameter was less than 1 μm, causing the microresonator to switch from being a band-stop filter to a bandpass filter. Larger bubbles with submicrometer wall thickness were also fabricated.     

相位匹配下锥形光纤激发出的回廊模谐振

分别计算不同直径下锥形光纤基模和玻璃微球谐振腔内最低阶径向回廊模的传播常量,利用相位匹配条件,作出了锥形光纤与石英玻璃微球腔的直径对应关系曲线.在此基础上,选择锥腰直径2.8 μm左右的低损耗锥形光纤与直径143.1 μm球形度很好的玻璃微球腔进行近场耦合以激发球内的最低阶径向回廊模谐振,在锥形光纤的两端进行通光测试,在输出端获得了等间距分布的窄线宽滤波谱线,其吸收峰位置与利用Mie理论计算的球内最低阶径向回廊模谐振峰位置相一致.     

Optical microsphere amplification system

We demonstrated a compact optical amplification system using a fiber taper and rare-earth-doped microsphere. Both the signal and pump beams were injected into the microsphere via the fiber taper to increase the spatial matching between two whispering gallery modes. As the pump power was increased, the resonance dip in the transmission spectra due to intrinsic attenuation in the microsphere became filled and then transited to the resonance gain peak. An amplification factor of up to 2.5 was realized with a microsphere of 63 microm in diameter.     

Fiber-coupled diode end-pumped Q-switched Tm,Ho:YLiF4 laser

At liquid-nitrogen temperature, at 10-kHz pulse repetition rate, Q-switched 36-ns pulses with average output power of 4 W at 2.05 μm and 4.5-W continuous wave output power with a total optical-optical conversion efficiency of 30%, were achieved from a 6% Tm, 0.5% Ho:YLiF4 laser. This laser was endpumped by a fiber-coupled laser diode emitting up to 15 W around 792 nm. The 1-m-long optical fiber carrying the pump radiation has a core diameter of 700 μm with a numerical aperture of 0.22.     

面向谐振式微光学陀螺应用的球形谐振腔DQ乘积优化

基于谐振式光学陀螺高灵敏度、低成本与微型化的发展需求, 为了实现高灵敏度的谐振式微光机电陀螺, 提出了以集成光学微谐振腔领域里高Q值、大直径谐振腔的制作为目标, 应用方向为谐振式光学陀螺的球形光学微谐振腔核心敏感单元. 在实验中以氢火焰作为热源采用熔融法制备球形光学微谐振腔. 通过调节氢气的流量控制氢火焰热源面积, 制备了不同直径(300-2200 μm)的球形谐振腔, 分析了球形谐振腔Q 值、DQ乘积、陀螺灵敏度与谐振腔直径D的对应关系及其原因, 获得了最优参数的面向谐振式光学陀螺的球形谐振腔敏感单元. D=1260 μm时, 球腔品质因数 Q=7.18×10⁷, 得到的最优陀螺灵敏度约为10°/h, 满足商业级应用的需求, 为芯片级、高精度、低成本的新型谐振式光学微腔陀螺的研究奠定了实验基础.     

石英玻璃微球吸收光谱上的结构共振

通过CO2激光器熔融不同直径的熔锥光纤以得到相应直径的石英玻璃微球,利用此微球和熔锥光纤,构造了球微腔耦合系统。实验中利用光腰直径为3.1μm的熔锥光纤与直径为143.1μm的石英玻璃微球进行耦合,通过最大分辨力为1pm的可调谐半导体激光器对该耦合系统进行光谱扫描,发现石英玻璃微球的吸收光谱中出现分立的结构共振峰。利用光学微球腔理论讨论了石英玻璃微球吸收光谱中的结构共振,并用米氏散射理论公式对一阶TE模共振峰的位置以及它们的间隔进行了计算,共振峰位置实验结果与理论结果的误差仅为0.03%,表明实验与计算结果相符。     

Supercontinuum generation at 1.55μm using highly nonlinear photonic crystal fiber for telecommunication and medical applications

In this paper, we present a theoretical calculation of a highly nonlinear germanium (Ge) doped photonic crystal fiber with all-normal group velocity dispersion to design a supercontinuum (SC) light source at 1.55 μm. By doping 3% higher refractive index Ge inside the host silica, the nonlinear coefficient is increased to a value as large as 60.5 W^?1 km^?1 at 1.55 μm. A 10 dB bandwidth of a 120 nm SC spectrum for a 2.5 ps input optical pulse and a 10 dB bandwidth of a 190 nm SC spectrum for a 1.0 ps input optical pulse have been found using the same fiber length of 200m and input optical power of 18 W. The coherent lengths of the generated SC light sources are found to be 8.8 μm for a 2.5 ps input optical pulse and 5.6 μm for a 1.0 ps input optical pulse. Therefore, the highest longitudinal resolution at 1.55 μm is found to be about 4.0 μm for biological tissues.     

方形渐变空气孔微结构光纤的色散特性分析

提出了一种新型的方形分布渐变空气孔微结构光纤。借助时域有限差分法计算了孔间距取 2.0μm和2.5μm,最小孔直径分别取0.4μm、0.6μm、0.7μm、0.8μm和1.0μm,从第一层到第五层直径线性递增量分别为0.1μm/层和0.2μm/层的五层渐变空气孔微结构光纤的基模色散曲线图,结果表明渐变空气孔微结构光纤在控制色散的能力上明显优于空气孔不变的微结构光纤,这种光纤的色散曲线在1400~2000 nm波长范围内保持平坦且具有更低的色散量;当渐变空气孔微结构光纤第三层孔的直径取与孔直径不变微结构光纤的孔直径相同,且第一层到第五层孔直径按每层0.2μm的斜率增长时,其色散曲线最低最平坦,色散值保持在30 ps/(km·nm)左右。     

采用保偏光子晶体光纤在1.6μm区域产生超连续谱

报道了利用保偏光子晶体光纤在1.6 μm区域产生超连续谱.通过将光参量放大器产生的中心波长为1.5938 μm、重复频率为250 kHz、脉冲宽度为250 fs的光脉冲耦合进纤芯直径为2.0 μm、长度为0.2 m的保偏光子晶体光纤,获得了1.6 μm区域的光谱展宽,展宽的光谱带宽为45.8 nm (1.5892~1.6350 μm).     

超细低水峰抗弯损光纤的设计及制作

采用全合成预制棒制造法（VAD＋OVD）和改进的G.652.D光纤拉制法制造光纤.研究了工艺中光纤芯径的大小、第一包层的厚度、芯包折射率差、芯包比等参量与光纤弯曲性能的关系,并据此制作了几种超细低水峰抗弯损光纤.该光纤的裸光纤直径约80 μm,涂覆后成品光纤直径约140 μm,当弯曲半径不小于7.5 mm时,能够在1 260～1 625 nm整个波段内满足DWMD的传输要求.     

LD-clad-pumped nanosecond Tm<Superscript>3+</Superscript> doped silica fiber amplifier at 1.99 μm

ALD-clad-pumped nanosecond Tm³⁺ doped silica fiber amplifier was reported that provided up to a 2-W average power output with a slope efficiency of 48.6% with respect to the absorbed pumped power. The input signal central wavelength was at 1.99 μm, with a 119.5-ns pulse duration and 5-kHz repeat rates. The pump sources were a 793-nm LD output with a 400-μm pigtail fiber. The gain fiber was D-shaped Tm³⁺ doped silica double-clad fiber with a diameter of 27.5/400 μm. The output amplified pulse and spectrum were in accordance with the input signal. This is the first report to the authors’ knowledge on the general experimental investigation of a LD-clad-pumped Tm³⁺ doped silica nanosecond-fiber amplifier at 1.99 μm.     

Elastic scattering from a sapphire microsphere placed on a silica optical fiber coupler: Possible applications to biosensing

Elastic light scattering is performed in the original band of optical fiber communication at 1300 nm for a 500 μm sapphire microsphere placed on a silica optical fiber half coupler. The morphology dependent resonances (MDRs) are observed in the transverse magnetically (TM) polarized and transverse electrically (TE) polarized 0^° transmission and 90^° elastic scattering obtained from the sapphire microsphere. The TE and TM MDRs can be detected selectively with the use of a Glan polarizer. The TE and TM polarization selectivity provides the ability to select relative MDR to BG levels. The TM polarization provides higher MDR signal to background ratio (SBR) and is suitable for optical monitoring, biological sensing or any other optoelectronic application that requires a high resolution optical filter. The polar angular mode spacing of 0.36 nm of the resonances correlates well with the optical size of the sapphire microsphere. The autocorrelation of the 90^° elastic scattering spectra also shows peaks at 0.36 nm. The spectral linewidths of the resonances are on the order of 0.1 nm, which corresponds to quality factors on the order of 10⁴. A sapphire sphere with a radius of 500 μm and relative refractive index of 1.31, resonances will red-shift by 1.01 nm (0.077%). This shift is on the order of 10 linewidths, making sapphire biophotonic sensors an interesting alternative to silica biophotonic sensors.     

A Study of the Optical Properties of a Multimode Silica Optical Fiber with a Reflective Shell from a Fluorinated Thermoplastic Polymer

Optics and Spectroscopy - The optical properties of a silica–polymer optical fiber with a light-guide core with a diameter of 430 μm and a reflecting shell with a thickness of 70 μm...     

A method for reducing optical fiber diameter fluctuations

An optical fiber diameter monitor, Type GY-A, was developed especially for fiber drawing. A new method, the pulling force-temperature method, is presented. The fiber drawing stability is improved and the fluctuation of the fiber diameter is 0.3 μm (rms).     

光纤传输激光驱动飞片实验研究

构建了一种基于光纤传输高功率激光的飞片发射系统,并测试了飞片速度.飞片膜层为三明治结构:铝烧蚀层、氧化铝隔离层和铝飞片产生层.飞片膜层采用磁控溅射技术沉积在玻璃衬底上,总厚度为5.5 μm.激光辐照铝膜层产生高温高压等离子体,驱动剩余膜层产生高速飞片,速度达数km/s.同时,实验研究了光纤传能系统的输出激光空间分布特性和传输激光能量容量,它们决定了飞片的平面性和最大速度.光纤端面损伤是限制光纤传输激光能量容量的关键因素,光纤端面通过精密机械抛光和激光预处理可以获得理想的抗激光损伤能力.采用基于光纤阵列探针的时间序列测试技术获得了飞片的平均速度,并评估了飞片的平面性.采用搭建的基于光纤传输高功率激光的飞片发射系统获得了速度达1.7 km/s、直径接近1 mm的高速飞片. 关键词： 激光驱动飞片 激光辐照 光纤阵列探针 激光等离子体     

Compact, high-pulse-energy, picosecond optical parametric oscillator

We report a high-energy optical parametric oscillator (OPO) synchronously pumped by a 7.19 MHz, Yb:fiber-amplified, picosecond, gain-switched laser diode. The 42-m-long ring cavity maintains a compact design through the use of an intracavity optical fiber. The periodically poled MgO-doped LiNbO(3) OPO provides output pulse energies as high as 0.49 μJ at 1.5 μm (signal) and 0.19 μJ at 3.6 μm (idler). Tunability from 1.5 to 1.7 μm and from 2.9 to 3.6 μm is demonstrated, and typical M(2) values of 1.5 × 1.3 and 2.8 × 1.9 are measured for the signal and idler, respectively, at high power.     

微磨削斜面光纤透镜平面度试验研究

为了研究微磨削参数对斜面光纤透镜平面度的影响,减小微磨削方法加工斜面光纤透镜的平面度误差,采用正交试验法对直径Ф125 μm单模光纤的30°斜面光纤透镜的微磨削进行了试验。结合微磨削的磨削力模型和材料力学弹性梁变形理论, 分析微磨削过程中随着磨削用量的变化所导致的光纤透镜被磨削斜面的平面度的变化规律。理论分析和实验结果表明:光纤悬伸长度对斜面光纤透镜平面度的影响最大,增大光纤悬伸长度将导致较大的斜面光纤透镜平面度的轮廓误差,恰当的磨削用量组合能够获得较小的平面轮廓误差。通过试验磨削出了平面度误差为3 μm的30°斜面光纤透镜。     

The Effect of the Geometry and Mode Composition of Radiation on the Diffusing Properties of a Quartz–Polymer Optical Fiber with a Tefzel Light-Reflecting Shell

Optics and Spectroscopy - Numerical calculation of the hybrid modes is performed for a quartz–polymer optical fiber with the diameter of the optical fiber core of 400 μm and a diffusing...