We present a theoretical study on the frequency position and the linetype of Electromagnetically Induced Transparency
(EIT) in a four-level atomic system with a coupling field, two microwave fields and a probe field. The absorption
spectrum which is characterized by two EIT windows is obtained by a weak probe field scanning corresponding
transition. It can be found that the frequency position and the linetype of EIT change with the relative phase of the two
microwave fields. The frequnecy interval reaches the minimum when the relative phase is reverse. If two microwave
fields have the same strength and reverse phase, the absorption spectrum will exhibit an EIT. This proposes a way to
controlling frequency position of EIT by modulating the relative phase between two fields.
In this paper we study the coherent transient property of a Λ-three-level system (Ωd = 0) and a quasi- Λ -four-level
system (Ωd>0). Optical switching of the probe field can be achieved by applying a pulsed coupling field or rf field. In
Λ -shaped three-level system, when the coupling field was switched on, there is a almost total transparency of the probe
field and the time required for the absorption changing from 90% to 10% of the maximum absorption is 2.9Γ0 (Γ0 is
spontaneous emission lifetime). When the coupling field was switched off, there is an initial increase of the probe field
absorption and then gradually evolves to the maximum of absorption of the two-level absorption, the time required for the
absorption of the system changing from 10% to 90% is 4.2Γ0. In four-level system, where rf driving field is used as
switching field, to achieve the same depth of the optical switching, the time of the optical switching is 2.5Γ0 and 6.1Γ0,
respectively. The results show that with the same depth of the optical switching, the switch-on time of the four-level system
is shorter than that of the three-level system, while the switch-off time of the four-level system is longer. The depth of the
optical switching of the four-level system was much larger than that of the three-level system, where the depth of the
optical switching of the latter is merely 14.8% of that of the former. The speed of optical switching of the two systems can
be increased by the increase of Rabi frequency of coupling field or rf field.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.