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光学工程
铷(Rb)激发态感生色散光学滤波器在775.9nm透射特性

Transmission characteristics of an excited-state induced dispersion optical f ilter of rubidium at 775.9 nm

 

The operation of an ultra-narrow bandwidth optical filter based on the 5P3/2 → 5D3/2 excited-state transition in rubidium vapor is reported. The 5D3/2 state is excited by a circularly polarized pump beam at 780 nm from a diode laser. The filter displays a single 398-MHz bandwidth at a peak transmission of 9.0%, which is narrower than the Doppler bandwidth. The dependence of peak transmission on the pump intensity and cell temperature is also given.

   OCIS codes: 120.2440, 300.6210, 300.2530, 020.4180.

With the development of laser communication and lidar[1?3], using an ultra-narrow pass-band optical filter to reject broadband background has become an important way to improve the signal-to-noise ratio (SNR) of the receiver systems. It is well known that conventional interference filters cannot provide extremely high transmission with ultra-narrow bandwidth. Laser-induced dispersion optical filter (LIDOF)[4?6] has the advantages of ultra-narrow band, high transmission, fast response, large field of view, and high noise rejecting capability. Compared with the Faraday anomalous dispersion optical filter (FADOF)[7?15], LIDOF does not need an external magnetic field and has higher transmission on excited-state transition.

   In this letter, we demonstrate a LIDOF at 775.9 nm pumped by a narrow-linewidth circularly polarized light, what is to our knowledge, firstly reported in rubidium vapor. We observed a single bandwidth of 398 MHz less than Doppler band width (about 600 MHz at 410 K) with a peak transmission of 9.0%. The dependence of peak transmission on pump intensity and cell temperature is also discussed. It should be noted that the wavelengths chosen in our experiment were some kind of simulation of green-band LIDOF, for instance, Rb 5P1/2 → 10S1/2 (532.24 nm), Rb 5P3/2 → 11S1/2 (523.39 nm), which was a compromise due to the lack of green-band laser source. But the method is general, the results are useful for green wavelength LIDOF.

   A LIDOF consists of