With the development of the optics communication system and optical signal modulation technology, the ampli-tude-shift keying (ASK) and phase-shift keying (PSK) are both used in different optical communication sub-networks. In this paper, a novel all-optical modulation format from PSK to ASK based on phase-sensitive amplification is pro-posed and demonstrated. Using the nonlinear interference of the single-pump phase-sensitive amplification, the signal wavelength can be preserved while the modulation format is conversed. The proposed scheme provides the flexible intermediate node interface transformation in future optical networks.

The rectangular optical filter is one of the most important optical switching components in the dense wavelength division multiplexing (DWDM) fiber-optic communication system and the intelligent optical network. The integrated highorder silicon microring resonator (MRR) is one of the best candidates to achieve rectangular filtering spectrum response. In general, the spectrum response rectangular degree of the single MRR is very low, so it cannot be used in the DWDM system. Using the high-order MRRs, the bandwidth of flat-top pass band, the out-of-band rejection degree and the roll-off coefficient of the edge will be improved obviously. In this paper, a rectangular optical filter based on highorder MRRs with uniform couplers is presented and demonstrated. Using 15 coupled race-track MRRs with 10 μm in radius, the 3 dB flat-top pass band of 2 nm, the out-of-band rejection ratio of 30 dB and the rising and falling edges of 48 dB/nm can be realized successfully.

针对薄膜滤光片倾斜入射时产生的偏振光中心波长分离现象和偏振相关损耗, 本文利用等效层理论设计了倾斜入射下中心波长消偏振的100 GHz信道间隔滤光片膜系结构, 实现了薄膜滤光片的角度和波长调谐。首先通过相位关系分析, 计算了滤光片间隔层的消偏振等效折射率, 实现了不同偏振光中心波长的对准。然后, 根据等效层理论, 设计三层对称膜层结构实现了对间隔层中心波长消偏振等效折射率的替换。与原有的五层规整低偏振薄膜滤光片相比, 本文提出的膜系结构更为简单, 对消偏振等效折射率的替换更为精确。仿真和实验结果表明: 该膜系结构的薄膜滤光片能实现0~20°倾斜入射的偏振光中心波长对准, 偏振光波长偏离度小于0.03 nm, 波长调谐范围能达到35 nm。

Conventional angle-tuned thin-film filters have serious angle sensitivity for their low spacer effective refractive index, and it is difficult to fabricate their angle control system. In this paper, we propose and fabricate a novel 100 GHz angletuned thin-film filter stack with low angle sensitivity, which uses the high refractive index material TiO2₂ as the spacer, and its incident angle can be expanded to 25°. Compared with the traditional Ta₂O₅-SiO₂ thin-film filter stack, the novel stack has fewer layers. Using the polarization beam splitters and the half wave plates, the polarization sensitivity of the angle-tuned filter can also be suppressed. Simulation results and the experiments show that the thin-film filter with low angle sensitivity has an effective tuning range of 33 nm, which can cover the whole C-band, and its angle control system is easy to be fabricated.

三端口可调谐滤波器是全光智能交换网络和密集波分复用系统中的核心器件.其反射端口的光谱特性,尤其是反射率和信道隔离度对于滤波器的性能至关重要.角度调谐滤光片因其良好的矩形度和温度稳定性被广泛应用于三端口可调谐滤波器的制备,其反射端口的光谱特性不仅与倾斜入射角度的大小有关,而且与其非平行端面间的楔角参量有关.文章详细分析了楔角参量对非平行角度调谐滤光片的反射率及半宽的影响,仿真计算了楔角参量在不同极性和大小条件下角度调谐滤光片的反射光谱特性,揭示了保持适当的楔角参量和方向性可以改善倾斜入射状态下滤光片的反射光谱特性.设计并制备了楔角为0.8°的楔形角度调谐滤光片,实验证明了当保持楔角方向与倾斜入射方向相同时会严重的劣化透反射光谱的半宽和隔离度,方向相反时则可以改善反射光谱的反射率和半宽指标.通过负楔角参量的引入使得角度调谐滤光片较之高平行度的同类器件具有更高的反射率和信道隔离度.

角度调谐薄膜滤光片因较大的波长调谐特性和良好的矩形度在密集波分复用系统中得到了广泛的应用。 在倾斜入射时薄膜滤光片透射光谱的透射率和半宽不仅受到入射角度的影响, 还跟滤光片两端面间的非平行度即楔角的大小有关。 详细分析了楔角对对滤光片透射率以及半宽的影响, 发现适当的楔角和角度取向能够改善倾斜入射状态下滤光片的透射光谱特性。 设计制备了楔角为0.8°的楔形薄膜角度调谐滤光片, 实验结果证明保持该楔角的方向与倾斜入射角度相同时会严重的劣化透射光谱的透射率和矩形度, 方向相反时则可以提高光谱的透射率以及矩形度, 并使器件的波长调谐范围增大约10 nm。

根据薄膜窄带滤光片在斜入射时的偏振特性, 提出了基于遗传算法的斜入射薄膜窄带滤光片膜系优化设计方法.根据开发的程序, 设计并制备了一组可用于18°倾斜入射的0.8纳米信道间隔的五腔薄膜窄带滤光片.该滤光片能有效地抑制斜入射时偏振光中心波长的分离现象, 降低器件的偏振相关损耗, 通过角度调谐能实现选择波长的改变.通过与针法设计的滤光片膜系相比, 遗传算法得到的膜系具有更高的矩形度、更大的波长调谐范围以及更低的偏振相关损耗.实验结果表明其满足设计要求并有超过25纳米的波长调谐范围.

实验研究了飞秒脉冲激光泵浦I类BBO晶体中自发参量下转换效应，以及产生的彩色锥形辐射现象.系统分析了各参量对二次谐波转换效率及彩色锥形辐射现象的影响.研究结果表明:蓝绿色锥形辐射具有最大的发散角，这与相位匹配理论模拟结果吻合;正入射时，增大泵浦光强及晶体厚度均会引起彩色锥形辐射亮度增加，且最大出射角中心波长往长波移动；不同光束偏振态下可依次观察到彩色锥形辐射、超连续现象.

针对多腔窄带薄膜滤光片在倾斜入射时会产生严重的偏振相关损耗问题，研制了一种基于双折射晶体偏振分束器、信道间隔为100 GHz 的角度可调薄膜滤波器。该方法可简化倾斜入射时多腔窄带薄膜滤光片消偏振膜系结构，通过对入射光信号偏振态的控制，仅使用常规窄带滤光片就能实现角度调谐其中心透射波长。该可调谐滤波器件具有结构简单、成本低和偏振相关损耗小的特点，实验测试证明其可调谐波长范围可覆盖整个C 波段。