REG: Infrared Laser, TV Camera and Fabry Perot for MM-Wave Modulator Research

NSF工程研究设备补助金 将使购买钕钇铝石榴石 红外激光器、红外电视摄像机和 红外扫描法布里-珀罗光谱 用于新型电光调制器研究的分析仪 在加州理工 在扩大业务的严重困难， 行波电光调制器到100 GHz（3 mm）区域是由色散引起的， 调制器材料，晶体锂酸盐。 的 光波在晶体中的传播速度 比调制波;因此， 调制过程在这些高的温度下不同步 频率. 加州理工学院正在研究的一项技术 将调制传输线分成 短段数，并驱动每个段 从它自己的微型偶极子天线集成在 水晶的表面。 天线由一个 从波导管辐射的平面波，入射于 保持调制波的正确角度 平均与光波同步。 作为 奖金，使用天线和辐射，而不是同轴电缆 连接器和接合线以耦合调制 消除了寄生电 这些元素在mm中非常有害- 波程 调制频率高达63 GHz（4.8 m） 已经与18 mm长的锂酸盐一起使用 具有良好的效率。 这些初始 实验使用633 nm的红色激光。 使用这种光纤的实用光纤系统 用于信息传输的调制器（电话， 有线电视、雷达信号等）都运行在1320或1550 然而，NM。 这笔赠款将允许延长 这种波耦合调制器的研究， 波长

This NSF Engineering Research Equipment Grant will enable the purchase of a Neodymium-YAG infrared laser, an infrared TV camera, and an infrared scanning Fabry Perot optical spectrum analyzer for novel electro-optical modulator research at Caltech. A serious difficulty in extending the operation of travelling-wave electro-optical modulators into the 100 GHz (3mm) region is caused by dispersion in the modulator material, crystalline lithium niobate. The optical wave travels through the crystal much faster than the modulation wave; as a consequence, the modulation process gets out of step at these high frequencies. A technique being studied at Caltech breaks the modulation transmission line into a number of short segments, and drives each segment from its own tiny dipole antenna integrated on the surface of the crystal. The antennas are excited by a plane wave radiated from a waveguide, incident at just the correct angle to keep the modulating wave in step with the optical wave on the average. As a bonus, using antennas and radiation rather than coax connectors and bond wires to couple the modulation to the transmission lines eliminates parasitic electrical elements that would be very detrimental in the mm- wave range. Modulation frequencies as high as 63 GHz (4.8 m) have been used with an 18 mm long lithium niobate modulator with good efficiency. These initial experiments employed red laser light at 633 nm. Practical fiber optical systems that use such modulators for information transmission (telephone, CATV, radar signals, etc.) all operate at 1320 or 1550 nm, however. This grant will allow the extension of this wave-coupled modulator research to those wavelengths.