为提高光学认证技术的安全性及实用性，提出了基于三维空间正交偏振态复用的光学多级安全认证方法。用所设计的多衍射平面多信号窗口相位恢复算法，生成两个相位模板，使由认证图像分割得到的子块图像分布于其三维菲涅耳衍射场的特定位置。一个相位模板作为系统锁，另一个作为认证密钥。用正交偏振光分别照明两相位模板，实现了三维空间衍射场内不同位置强度分布和偏振态分布的控制。只有同时具备认证密钥和三维空间正交偏振态映射密钥，才能恢复认证图像，模拟及实验结果与认证图像的相关系数分别为0.93 和0.79，表明该系统结构紧凑、安全等级高,可以实现分级认证。

A tunable two-section amplified feedback laser, which employs an amplifier section as the integrated feedback cavity, is designed and fabricated for dual-mode operation with mode separation of 100 GHz. Detailed simulations and experimental characterizations on the performance of the laser are presented. Promising dual-mode emission with continuous tuning range over 16 GHz (87.41–103.64 GHz) is experimentally demonstrated.

In holographic encryption, double random-phase encoding in the Fresnel domain (DRPEiFD) is a prevalent encryption method because it is lensless and secure. However, noises bring adverse effects during decryption. In this letter, we introduce quick-response (QR) coding during encryption to resist noises. We transform the original information into a QR code and then encrypt the code as a hologram through DRPEiFD. To retrieve the input, we decrypt the hologram in the opposite manner to the encryption and subsequently obtain a QR code with noises. By scanning this code with proper applications in smartphones, we can obtain a noise-free retrieval. Numerical experiments and images scanned by a smartphone are shown to validate our proposed method.

When using a single reference to measure the bi-directional scattering distribution function (BSDF), the incident zenith angle of the tested sample must be identical to that of the reference. In order to get the hemisphere space scattering characteristic on the sample surface, usually a motor drives the sample tilting, then the incident zenith angle is changed and needs to be the compensated by another motor. We mathematically deduce the expression of compensation angle when the incident zenith angle is changed by the rotation of motor. After the incident angle is compensated, the scattering zenith angle and azimuth angle are deduced too. The uncertainty of the system is 0.75%. Scattering measurements are performed on copper sample with visible light under different temperatures.

The robustness of the software-synchronized all-optical sampling for optical performance monitoring is estimated for 10-Gb/s fiber communication systems. It reveals that the software-synchronized algorithm is sensitive to the signal degradation caused by chromatic dispersion and nonlinearity in optical fibers. The influence of timing jitter and amplitude fluctuation of the sampling pulses is also investigated. It is found that stringent requirements are imposed on the quality of the sampling pulse and the tolerance of 1-dB Q penalty is measured. Considering the practically available optical sampling pulse sources, the results indicate that the amplitude fluctuation of the sampling pulses has the dominant impacts on the software-synchronized method.

A scheme to achieve ultrahigh speed all-optical format conversion from on-off keying (OOK) to phase-shift keying (PSK) by using the linear filtering in the silicon ring resonators is proposed. It is shown that the OOK-to-PSK conversion can be achieved through a linear signal processing. Simulation results are provided for the 160-Gb/s non-return-to-zero (NRZ)-to-PSK and carrier-suppressed (CS) return-to-zero (RZ)-to-(CS)RZPSK conversions.

A new method for testing aspheric surfaces by annular subaperture stitching interferometry is introduced. It can test large-aperture and large-relative-aperture aspheric surfaces at high resolution, low cost, and high efficiency without auxiliary null optics. The basic principle of the method is described, the synthetical optimization stitching model and effective algorithm are established based on simultaneous least-square fitting. A hyperboloid with an aperture of 350 mm is tested by this method. The obtained peak-to-valley (PV) and root-mean-square (RMS) values of the surface error after stitching are 0.433'lambda' and 0.052'lambda' ('lambda' is 632.8 nm), respectively. The reconstructed surface map coincides with the entire surface map from null test, and the difference of PV and RMS errors between them are 0.031'lambda' and 0.005'lambda', respectively. This stitching model provides another quantitive method for testing large aspheric surfaces besides null compensation.