Bichromatic electromagnetically induced transparency in hot atomic vapors

In a three-level $\Lambda$ atomic system coupled by a symmetrical bichromatic laser field, a weak probe laser field shows multiple absorption peaks in the case of cold atoms. As for hot atomic vapors, we experimentally observe double symmetrical electromagnetically induced transparency windows instead of multiple absorption peaks. This abnormal spectrum is due to the Doppler averaging. The electromagnetically induced transparency windows observed here are useful for obtaining slow photons at different frequencies.

Figure 1

Schematic representation of the light-atom interaction for bichromatic EIT and the probe absorption spectrum of the cold atoms obtained through the numerical simulations. (a)–(c) Symmetrical probe absorptions for ${\delta }_1=-{\delta }_2=5\Gamma =30$ MHz; (d)–(f) unsymmetrical probe absorptions for ${\delta }_1=-5\Gamma$, ${\delta }_2=-10\Gamma$; (b), (e) ${\Omega }_{c1}={\Omega }_{c2}=5\Gamma$; (c), (f) ${\Omega }_{c1}={\Omega }_{c2}=10\Gamma$.

Figure 2

The calculated probe absorptions of the hot atomic vapors for monochromatic EIT and bichromatic EIT. (a) Monochromatic EIT, ${\Omega }_c=10\Gamma$; (b) bichromatic EIT, ${\Omega }_{c1}={\Omega }_{c2}=10\Gamma ,{\delta }_1=-{\delta }_2=5\Gamma =30$ MHz.

Figure 3

The experimental configuration. AOM: acousto-optic modulator; M: mirror; BS: beam splitter; PBS: polarization beam splitter; Rb Cell: rubidium cell with magnetic shield and temperature controller.

Figure 4

Probe absorption as a function of the detuning of the probe laser for the $5S_{1/2},F=2\to 5P_{1/2}$ transition of ${}^{85}$Rb $D_1$ line. Solid red line: bichromatic EIT, ${\Omega }_{c1}={\Omega }_{c2}=9.3\Gamma$, ${\delta }_1=-{\delta }_2=30$ MHz. Dotted black line: monochromatic EIT, ${\Omega }_{c1}=9.3\Gamma$, ${\Omega }_{c2}=0$, and ${\delta }_1=30$ MHz. Dashed pink line: monochromatic EIT, ${\Omega }_{c1}=0$ ${\Omega }_{c2}=9.3\Gamma$, ${\delta }_2=-30$ MHz.

Figure 5

Probe absorption as a function of the detuning of the probe laser. (a) ${\Omega }_{c1}={\Omega }_{c2}=9.3\Gamma$, ${\delta }_1=-{\delta }_2=30$ MHz; (b) ${\Omega }_{c1}={\Omega }_{c2}=4.6\Gamma$, ${\delta }_1=-{\delta }_2=30$ MHz; (c) ${\Omega }_{c1}={\Omega }_{c2}=9.3\Gamma$, ${\delta }_1=60$ MHz, ${\delta }_2=0$ MHz; (d) ${\Omega }_{c1}={\Omega }_{c2}=9.3\Gamma$, ${\delta }_1=-{\delta }_2=20$ MHz; (e) ${\Omega }_{c1}=8\Gamma$,${\Omega }_{c2}=11\Gamma$, ${\delta }_1=-{\delta }_2=20$ MHz; (f) ${\Omega }_{c1}=10\Gamma$,${\Omega }_{c2}=8\Gamma$, ${\delta }_1=-{\delta }_2=20$ MHz.

Figure 6

Probe absorption as a function of the detuning of the probe laser. (a), (b) ${\Omega }_{c1}={\Omega }_{c2}=6\Gamma$, ${\delta }_1=-{\delta }_2=3$ MHz; (c), (d) ${\Omega }_{c1}={\Omega }_{c2}=6\Gamma$, ${\delta }_1=-{\delta }_2=1.5$ MHz; (a), (c) theoretical results; (b), (d) experimental results.