Survey of atomic transitions for absolute frequency locking of lasers for lightwave systems

The authors survey 26 excited-state transitions of argon (Ar), krypton (Kr), and neon (Ne) around 1.3 and 1.5 mu m. A 1200-lines-per-mm grating mounted on a piezoelectric translator forms the adjustable reflective element of an external cavity semiconductor laser, reducing the laser linewidth to <100 kHz, and affording tens of nanometers of tunability. The laser may be tuned continuously over a range of approximately 2 GHz between mode hops by scanning the cavity length with the piezoelectric translator. Single-frequency oscillation is verified by the 750 MHz confocal Fabry-Perot, and the wavelength is measured by a wavemeter.<>