We present the transformation of electromagnetically induced transparency (EIT) into narrow enhanced absorption with an on-resonant standing-wave coupling field in the 5S(1/2)-5P(1/2) transition of the Lambda-type system of (87)Rb atoms. When a coupling laser field was changed from a travelling-wave to a standing-wave that was made by adding a counter-propagating L(C) laser, the transmittance spectrum of the L(P) laser transformed the typical EIT into dramatically enhanced absorption, and a Bragg reflection signal was generated by the periodic modulation of atomic absorption. The reflected probe laser corresponding to a Bragg reflection was measured to be approximately 11.5% of the power of the incident probe laser. We analyzed the enhanced absorption signal and Bragg reflection spectrum as a function of the power and frequency detuning of the coupling laser.

An electromagnetically induced Bragg reflection with a stationary coupling field in an Rb vapor cell with a 6.67 kPa neon buffer gas was studied. When the coupling field was spatially modulated as a stationary wave, a transmission reduction of the probe field was observed, while simultaneously a reflected probe field was detected in the backward direction. Instead of absorbing a fraction of the probe laser in the Rb vapor, the modulated electromagnetically induced transparency medium reflected it, corresponding to a Bragg reflection. The spectrum in the 5S(1/2)-5P(1/2)Lambda-type system of (87)Rb atoms was investigated as a function of the coupling laser frequency detuning, the stationary coupling laser power, the vapor cell temperature, and the coupling laser power ratio.