Investigation For Simultaneous Generation Of Multiple Non-classical Light With Type Ⅱ Phase-matched Frequency Doubling

In this thesis, we reported the investigation for simultaneous generation of multiple non-classical light with type Ⅱ phase-matched frequency doubling both theoretically and experimentally. The following parts are presented:1. Introduced the roots and detailed category of second order nonlinearity processes, phase matching condition, theoretical model and criteria for squeezed state and entangled states.2. Listed the main factors that affect the doubling efficiency, including laser beam parameters and resonant cavity parameters. Analyzed the relation between nonlinear conversion parameter and the parameters we mentioned previously. Introduced the characteristic of several kind of cavity setup. Deduced the function relating pump power and second harmonic output power, pump power and doubling efficiency. With above knowledge and keeping efficiency, convenience in mind, designed a double resonant, standing-wave cavity made up of a semi-monolithic KTP crystal and a concave mirror. Type Ⅱ phase matching is achieved by heating the KTP crystal to 80℃. The pump source is a homemade, one Watt output, all solid state, single frequency laser. The maximum green output power of 849 mW is obtained when the input fundamental power is 1.18 W. The direct measured doubling efficiency is 72%, if thetransmission coefficient of 90% of output mirror is taken into account it should be 80%. When both the fundamental laser system and frequency-doubling cavity are locked, the green light frequency stability is better than ±246 KHz in 1 minute and ±2.3 MHz in 30 minutes, respectively. The resulting doubling cavity can be used as a generic green light source or as a platform for further research on nonclassical processes of doubler.3. Deduced classical dynamic and quantum noise spectrum of type II resonant doubler by solving the quantum Langevin equation. There are two modes in the cavity: the one polarized parallel to the pump light is called 'bright mode' while the other is called 'dark mode' which polarized perpendicular to the pump light. Type II frequency doubling process can be divided into two processes: a type I phase matched doubling process and a parametric down conversion process. The latter has a threshold. When pump power is below this threshold, there is only vacuum seeded parametric amplification process in the cavity. Energy flow from bright mode to harmonic mode. When pump power goes above threshold, parametric oscillation sets in. Energy flow from bright mode to dark mode with harmonic mode act as bridge. The dark mode outside of cavity now has a non-zero amplitude. All work in this thesis is limited to the condition below threshold. The reflect dark mode is a squeezed vacuum with the theoretical maximum squeezing of 100%. The reflectbright mode is an amplitude squeezed light with the theoretical maximum squeezing of 1/3. The output harmonic light is bight amplitude squeezed light, with the theoretical maximum squeezing of 8/9. The above three types of nonclassical light are all generated experimentally. The maximum squeezing we obtained is 3.2 ± 0.1 dB (-52%) for vacuum and 1.3 ± 0.2 dB (-25%) for bright amplitude squeezed light with 8mW pump power when measure at the same time. The maximum squeezing of 5.0 + 0.2 dB (-68%) for squeezed vacuum can be reached if the pump power is optimized for it separately. The maximum squeezing of 3.1 ± 0.2dB (-51%) is obtained for amplitude squeezed harmonic output under 50mW pump power.4. Investigated the entanglement character between the two intrinsic modes of type II phase matched doubler and came to the knowledge that their amplitude is anti-correlated and their phase is correlated. This type of entangled light can be measure with 'Bell state direct detection system' without the need of local light. Proved that two entangled intrinsic modes can be restored out of cavity by mixed the two coupled mode on a 50/50 optical beam splitter. In this way, a pair of entangled light beam is obtained with amplitude sum noise 0.2±0.1 dB below SNL and phase difference noise 1+0.2 dB below SNL.The completed creative works are as follows:1. 849mW of 540nm laser is generated with type II phase matched resonant...