Sub-Doppler bandwidth atomic optical filter

Abstract

We demonstrate what is to our knowledge the first atomic optical filter that uses velocity selection to achieve a passband width that is less than the Doppler width of the filtering transition. A narrow-linewidth pump laser is used to induce circular birefringence in a narrow velocity class of atoms in a dense potassium vapor for 694-nm light resonant with the 4P(3/2)-6S(1/2) transition. The filter displays a single 170-MHz passband at a peak transmittance of 9.5%. The bandwidth is an order of magnitude lower than that of previously demonstrated atomic optical filters.

Theory and experiment for atomic optical filter based on optical anisotropy in rubidium

“…In this paper, we obtain a single peak transmission of 14.4% higher than the one reported by Turner et al [15], while the filter bandwidth of 396 MHz is broader than the one reported by Turner et al It is mainly because higher pump intensity than that of [15] is used in our experiment. The peak transmission efficiency increases as the pump intensity does at the expenses of a broader filter bandwidth.…”

“…For example, Faraday anomalous dispersion optical filter (FADOF) based on Faraday effect has been extensively studied [5][6][7][8][9][10][11] and has been utilized to many practical applications, such as laser communication [12] and lidar [13], with their merits of high transmission, narrow-bandwidth and excellent out-of-band rejection. In addition, atomic optical filters based on optical anisotropy induced by another selective-polarized pumping beam were preliminarily experimentally demonstrated [14][15][16], however, the theoretical model and the analysis of filter characteristics for this category of filter have not been reported.…”

Study of the effect of repump laser on atomic line filter

“…FWHM of ALF (ΔW ALF ) also obeys the ∞ p I nature, which shows that, with increasing pump power, the broadening will set in. These results are consistent with the earlier ones [17,18].…”

“…As it is relatively easier to realize IDEALF, several groups [17,18] have done experiments with different samples like K, Rb, etc. However, other than an earlier experimental report by Turner et al [17] and theoretical treatment by Liu and co-workers [22,23], the issue of application of an additional pump in the ALF level scheme has not been addressed so far. Since the IDEAF is related to population transfer by two step excitations, it is justified to expedite the role of repump in a more detailed manner.…”

“…Different types of optical filters have been reported earlier; they include Faraday anomalous dispersion optical filter [13][14][15], induced dichroism excited atomic line filter (IDEALF) [16][17][18], etc. Recently, Cerè et al [19] reported on using velocity-selective optical pumping signal for executing an atomic filter on resonance.…”