This paper reports that two identical external-cavity-diode-laser （ECDL） based spectrometers are constructed at 634nm referencing on the hyperfine B-X transition R（80）8-4 of 127I2. The lasers are stabilized on the Doppler-free absorption signals using the third-harmonic detection technique. The instability of the stabilized laser is measured to be 2.8 × 10^-12 （after 1000 s） by counting the beat note between the two lasers. The absolute optical frequency of the transition is, for the first time, determined to be 472851936189.5 kHz by using an optical frequency comb referenced on the microwave caesium atomic clock. The uncertainty of the measurement is less than 4.9 kHz.
An optical flequency comb phase-locked on an iodine frequency stabilized diode laser at 634 nm is constructed to transfer the accuracy and stability from the optical domain to the radio frequency domain. An external-cavity diode laser is frequency-stabilized on the Doppler-free absorption signals of the hyperfine transition R（80）8-4 using the third-harmonic detection technique. The instability of the ultra-stable optical oscillator is determined to be 7 ×10^-12 by a cesium atomic clock via the optical frequency comb＇s mass frequencv dividing technique.
We present a novel design of a compact, stable, and easy-adjustable semiconductor optical amplifier （SOA） system. This SOA system is capable of providing up to 560-roW laser power at the wavelength of 852 nm. For the continuous-wave （CW） seeding laser, the amplification gain can reach 18 dB. We add amplitude modulation onto the CW laser and measure the modulation amplification between seeding and output laser. The amplification gain remains constant within the frequency range from 10 Hz to 1 MHz. The whole system could work in ultra-stable condition： for CW seeding laser, the fluctuation of output power is less than 0.33% in several hours.
