Development of Optical Synthesizers

Abstract

We have developed a single-frequency continuous-wave laser source with an emission range from green to mid infrared (550 - 2830 nm, almost 2.5 octaves in the optical spectrum). This is to our knowledge by far the broadest tuning range of any single frequency source.<br />It employs a singly resonant optical parametric oscillator and a subsequent broadband frequency doubler. This source exhibits high output powers of typically 30 - 500 mW over most of the emission range, has near diffraction limited beam quality, and excellent spectral properties. It shows mode-hop-free oscillation for several hours and a high absolute frequency stability with a drift of less than 50 MHz per hour. The linewidth has been measured to be 20 kHz, one of the narrowest ever reported for an OPO.<br />A novel feature is a large continuous frequency tuning range up to 38 GHz ( > 1 / cm) without pump tuning.<br />This makes this OPO a versatile light source for a wide variety of applications such as high resolution spectroscopy, precision metrology, laser trapping and cooling, characterization of optical components, and many others. To demonstrate its performance, flexibility, and reliability it was used to measure a Doppler free hyper-fine spectrum of molecular iodine in the yellow spectral region.<br />We built two additional single frequency OPOs, which represented a significant step in scientific research at the time they were developed, and several high power single frequency pump sources in the green and infrared.