Laser System For Atom Interferometer Based Weak Equivalence Principle Test

The equivalence principle is one of the basic assumptions of general relativity and the weak equivalence principle(WEP)is a main part of equivalence principle.The high-precision test of the WEP is an important way to explore new physical theories and explore new interaction forces.As a rapidly developing high-precision measurement tool,atom interferometers(AIs)have important applications in measurement of inertial physical quantities and basic physics constants,and also test of fundamental physical principles.AIs use lasers to achieve precise manipulation of atoms.Laser systems play a pivotal role in AIs.Aiming at a precision of 10-10 level,we concentrate on the coherence,the efficiency and long-term frequency stability of lasers.This thesis mainly studies the laser system of AI used for WEP test.The innovative research results obtained are as follows:1.A rubidium vapor absorption cell system is implemented.Our system can test the spontaneous emission of laser source which is difficult to detect by laser beat frequency,F-P cavity system and spectrometer.This system is used to detect and analyze various lasers to find their optimal working conditions.The optical quality of laser is improved with our system and the coherence of atoms is also improved with the laser.2.A time-division multiplexing technology for single-pass and double-pass taped-laser-amplifier is implemented.The gain under double pass TA mode is improved by more than 50 times.This technology helps our system to use the laser efficiently in WEP test.3.A high-efficiency multi-pass acousto-optic frequency shift system is implemented.For the first time a frequency shift range of 5 GHz with acousto-optic frequency shift system was achieved which covers all laser frequencies required by the dual-species AI and a 800 MHz wide-range,narrow-line-width laser frequency scanning is achieved.This technology together with modulation transfer spectrum(MTS)based laser frequency stabilization system and optical phase locking loop system can improve the long-term stability of laser frequency in WEP test.The improvements for laser system contribute a lot in experimental research of WEP test using 85Rb-87Rb dual-species AI.With other improvements in the AI system,the precision of WEP test was improved to about 1×10-10 compared to our result in 2015 which is 8×10-9.The Eotvos parameter was measured as ?=(-4.4±6.7)×10-10,this result is currently at the leading level of similar experimental research in the world.