Research On The Dressing Phase In Rydberg Multi-Wave Mixing Processes With Frequency Stabilization

The invention of lasers gives rise to the great development of atomic optics,and the strongly coupling between laser lights and external electrons can render the unexpected change of the optical response of the atomic media.In the current thesis,we have established the experimental system for studying the high-order nonlinear optical effect in multi-level rubidium atomic systems based on external cavity diode lasers?ECDLs?,and investigated the interaction between the coexisting high-order nonlinear multi-wave mixing?MWM?processes involving in the lowly-and highly-excited Rydberg levels with the assistance of the electromagnetically induced transparency?EIT?and optical pumping effects.The MWM processes with multi-dressing can be applied for multi-channel optical communication and information processing.Firstly,we have implemented a controlling system for driving ECDL based on analog electronics technique,and such a servo system can be applicable to the ECDLs?with wavelength 780nm,776nm and 795nm?for the energy level transition in rubidium atoms.By analyzing the structure and characteristics of the ECDL,we propose the scheme for implementing the structure of the servo system consisted of the current driver,the temperature controller,and the active frequency-stabilizing system for narrowing the linewidth and holding the output frequency.We also propose the performance index of each module depending on the experimental requirement,and design the circuit diagram in detail.At last,the whole circuit scheme is realized with hardware and the circuit performance can meet the requirement after carefully debugging.Ultimately,we assemble all the modules to produce a complete instrument,by which we can manipulate the ECDLs easily and safely.The high-performance driving and frequency-stabilizing system for the ECDL can not only meet the requirements of atomic experiment with high precision,but also be used for teaching and commercial developing due to its simplicity,low cost and reliability.So developing such a servo system can have outstanding practical significance and social value.Secondly,we realize the stable scanning system for optical ring cavity resonators.With the thermal rubidium vapor placed in a three-mirror ring cavity,the strong coupling regime can improve the nonlinearity of medium effectively.Meanwhile,we place a periodically poled KTP crystal in a four-mirror cavity to obtain the second-harmonic generation?SHG?,namely,the frequency-doubling technique.However,we need to to construct a external controlling system to maintain the long-term stabilization of the cavity length of three-mirror cavity and resonance between the four-mirror cavity and the fundamental-frequency wave.As a result,the drift?uncertainty?of the dressing MWM processes in the atomic cavity can be suppressed to less than 4 MHz when locked.During the experiment,the existence of the atomic cavity can be viewed as a cavity-dressing field and the frequency-doubling light can also be viewed as dressing field.To obtain the disturbance-free dressing signal,we use the scanning dressing field method,which means the two ring cavities should be able to track the scanning of corresponding reference lasers under stabilized condition.As a consequence,we implement two sets of negative feedback system to guarantee the cavity can be scanned over 1GHz with a frequency of 10Hz under locked condition.Thirdly,we investigate the phase control and interaction in the coexisting MWM processes by use EIT technique and optical pumping effect in a lowly-excited rubidium atomic system.We demonstrate the coexisting four-wave mixing?FWM?and six-wave mixing?SWM?processes which can be enhanced both by EIT and optical pumping effect in a common three-level and open four-level inverted-Y type systems of ⁸⁵Rb.And the effect of optical pumping in different energy level systems is analyzed by arranging laser beams and comparing the strength of the increased and reduced absorption caused by optical pumping.Furthermore,we have experimentally demonstrated the phase change of the coexisting probe,SWM and fluorescence signals in coherently prepared K-type rubidium atoms by controlling the angle between the probe and corresponding dressing beams.In the meanwhile,the dressing effects can also be influenced with different hyperfine levels of the five-level system choosen as the ground state.The coexisiting nonlinear processes with controllability could be applied for new type photoelectric device and optical information processing,and accumulate rich experience for the generation of highly-excited Rydberg effect.Finally,based on the generated MWM processes in the lowly-excited atomic system,we investigate the high-order MWM process and the phase modulation involving in the highly-excited Rydberg states with the utilization of EIT spectrum.On one hand,we have theoretically and experimentally studied the coexisting eight-wave mixing?EWM?and SWM processes with Rydberg dressing in multi-EIT windows in hot rubidium atoms.By utilizing the optical detection method based on scanning dressing field,the Rydberg EWM with multiple spin coherence can be obtained with the assistance of the interaction and competition between the dressing and blockaded effects from the Rydberg atoms.The generated Rydberg EWM process in the multi-EIT windows can possess of a narrower linewidth less than 30 MHz.On the other hand,we theoretically and experimentally demonstrate the enhancement and suppression properties caused by different high-order multi-waving mixing?MWM?with Rydberg dressing in a multi-level coherent ⁸⁵Rb vapor.The Rydberg-interaction induced nonlinear dispersion of the atomic medium can lead to a phase shift with nonlinearity between dark and bright states.The observed nonlinear phase shift can be quantitatively mapped onto the dressing asymmetry of the MWM spectra with enhancement and suppression.Current study on phase shift is applicable to phase-sensitive detection.