Investigation On Tuning And Control Of Laser In Atoms And Communication Band

All-solid-state CW single frequency tunable Ti:sapphire laser, with the advantages of wide spectral range, high output power, easy to usage, narrow line width and solid, is widely used in high sensitive interferometers, high resolution laser spectroscopy, detection of gravitational waves, quantum communication, atomic cooling and other basic physics research fields.All solid continuously tunable single-frequency Ti:sapphire laser, as a representative of the tunable lasers, has such unique advantages as wide spectral range, narrow linewidth, low phase noise, and high power. It has be used as a important light source in the field of quantum communication, quantum information processing, and laser spectroscopy.View of the all-solid-state continuous single-frequency tunable Ti: sapphire laser in our laboratory and other scientific fields have a wide range of applications, in order to promote the development of our laboratory basic research and applied research and to accelerate the pace of innovation in our country, we do a series of research works in the double refraction filter set design, the lock of etalon inserted in cavity, the low noise high voltage amplifier which is needed in the tuning system, and the control system which is used in pump source of high power single frequency green laser.1. A design of a high-power tunable single-frequency low-noise green laser. The laser is end-pumped by LD. A figure-eight-shaped ring resonator is constructed by four cavity mirrors. A wedge-shaped composite Nd:YVO4gain crystal, a frequency doubling crystal LBO, and a optical diode is put in the ring resonator. The laser output power is10.7W which is continuous single frequency green laser pumped by47W. The output power stability is better than±0.64%in the3hours. On this basis, frequency tuning of the laser is achieved by changing the operating temperature of the etalon. The frequency tuning range of the fundamental is12GHz, and the corresponding harmonic tuning range is24GHz under the etalon temperature change of about14℃. As a good laser source it can be used in the optical frequency standard based on the hyperfine peaks of molecular iodine, since its frequency-tuning range has covered several absorption lines of molecular iodine2. Designed and completed a LOCK-IN, etalon signal detector and galvanometer motor control signals and other critical electronic equipment. The etalon is locked in the laser light within the cavity. This creates the condition for the experiment of the continuous tuning research. By the use of the normal incidence TGG+half-wave of the optical isolators, an influence that the TGG and the half wave plate hinder continuous tuning is found. Then Brewster angle incident TGG crystal and natural optical rotation compensation-chip optical isolators is designed and completed. During the experiment a phenomena of over-compensation is discovered. That is the result of omitting of s light reflection. The design method of natural optical rotation compensation plate is concluded that the s light reflection must be considered in order to avoid over-compensation. This accumulated experience in design work for future experiments.In the continuous tuning experiment using Brewster angle incident TGG+a natural optically compensation plate structure optical diode, the results of the continuous tuning of20GHz ultimately is obtained.Ti:sapphire laser is with a wide wavelength tuning range. The780nm light waves exactly correspond to the rubidium atomic transition line F3/2-F1/2. It can be used in effectively trapping and cooling of rubidium atoms. As pump light of wavelength780nm laser,1560nm entangled source for the study of quantum confidential communication is also available by the use of OPO technology. So it can provide high quality light source for the study of rubidium atoms and quantum optical communications.3. LD pump source controlled by microcomputer control system is designed and completed. Supporting the use of10W single single-frequency green lasers which produced by our institute, the control system achieve the desired effect. During the work, a hardware PCB is designed, and through software programming to achieve a predetermined goal. The pump system achieves uniform temperature changes for boubling crystal LBO in power on and power off process. The operation logical sequence is controlled by the program. In the case of abnormal operation condition the control system automatically enter the shutdown process, to avoid security risks brought about by a number of human errors. In the current setting, because the program sets the maximum current limit the operation current does not appear over-flow damage to the LD. The operation is more convenient and safer than before.4, A low-noise high-voltage amplifier is designed and completed. By the level moving circuit the output voltage of operation amplifier is moved to the level that is over300voltages lower than the operational amplifier. The operational amplifier output voltage change is transmitted to the final stage between gate and source of the high-voltage N-channel MOS transistor, so that the low voltage operational amplifier and work with high voltage transistors.The amplifier is used more than two years in our laboratories. The result is satisfied, and meet the needs of precise experiment that request high voltage low noise amplifying. On this basis, a national patent application is submitted, and on January23,2013the patent is authorized by the State Intellectual Property Office.Innovative work:A. Using the thin etalon temperature changes to achieve a wide range of laser frequency tuning.B. Brewster angle incidence TGG+natural optical rotation compensation plate to avoid etalon effect in continuous tuning of the laser. Point out the problem of over-compensation of natural optically compensation plate and causes. So that can compensate more effectively.C. the etalon is locked with laser frequency. This creates the conditions for the study of the problems in the process of continuous tuning. D. Using the single chip machine to control the laser pumping source, so that the whole system is easier and more reliable to operate.E. design level Moving circuit, the operational amplifier output signal down over300volt drive high voltage MOS transistor in the high voltage amplifier.