Optical frequency standard by using a 1560 nm diode laser locked to saturated absorption lines of rubidium vapor

A robust, compact, highly accurate rubidium optical frequency standard module was developed to overcome the delicate performance of conventional frequency stabilized lasers. A frequency doubled 1560 nm distributed feedback diode laser locked to a rubidium D(2) saturated absorption line without using an optical amplifier was demonstrated, and dithering-free optical output was obtained. In addition, the sensitivity of the developed optical frequency standard to magnetic fields was investigated. We confirmed that the influence of the magnetic fields on the optical frequency standard can be almost negligible when using appropriate magnetic-shield films. As a result, the magnetic-field-insensitive optical frequency standard, which can be embedded in optical systems, exhibiting uncertainty less than at least 100 kHz, was successfully realized for the first time to the best of our knowledge.