A novel label erasion scheme based on a FP-SOA is proposed for all-optical separation of the subcarrier multiplexing
(SCM) label from payload and its performance is investigated by simulation. Fabry-Perot semiconductor optical
amplifier (FP-SOA) is attractive not only due to simple fabrication without anti-reflection coating step but also due to its
signal amplification capability and strong nonlinearity to perform all-optical label processing. Important features of this
scheme are that it does not make use of any high-speed electronics. Using FP-SOA as optical SCM label eraser,
more than 9db extinction ratio can be obtained. Meantime the payload can be amplified by more than 11dB.
In this scheme, FP-SOA acts as a low-pass filter as while as an amplifier.
A novel label abstraction and erasion scheme based on a FP-SOA is proposed for all-optical separation of the bit-serial label from payload and its performance is investigated by simulation. Fabry-Perot semiconductor optical amplifier (FP-SOA) is attractive not only due to simple fabrication without anti-reflection coating step but also due to its signal amplification capability and strong nonlinearity to perform all-optical label processing. Important features of this scheme are that it does not make use of any high-speed electronics and that only one device is needed. Using this scheme, label abstraction and erasion can be realized with the extinction ratio of 9.72 dB and 7.05dB, respectively. And the influence of pulse width ratio between the label and payload pulse on the extinction ratio is also investigated. We find that for a given case, there must be an optimized pulse width ratio to make the extinction ratio largest. It depends on working points of the label pulses and payload pulses in the gain curve.
It is believed that combining the techniques of smoothing by spectral dispersion (SSD) in the time domain and diffractive optical elements (DOE) in the space domain can improve beam uniform illumination. Adding another SSD unit to the combined system in different grating direction can disturb the incidence wave front more confused, thus the number of speckle patterns in the target plane is increased. The intensity in the target plane becomes smoother after a period of accumulation. However, the wave front distortion is limited by the dimension number of grating directions and the intensity distribution in each direction. In this paper we introduce the air turbulence and study its influence on the wavefront. The disturbance on wave front acts as an infinite aggregate in the number of direction dimension and intensity dimension because of the property of turbulence. The numerical calculation indicates that introducing disturbance by air turbulence on amplitude and phase of the light beam that incident to DOE can smooth the distribution on target plane after a period of accumulation.
A design of multi-step diffractive optical element (MDOE) is developed for the high power laser output smoothing. A hybrid algorithm is presented which inserts a quasi-optimum process in every iterative loop. This method of MDOE design saves the computing time tremendously. The top profile error (TPE) is about 8.4%, which looks inferior to what we have gotten in the earlier years with using continues profile design, but very easy in manufacture to match the design data. Now this MDOE with 16 steps on the surface of K9 glass can be realized with four masks' etching facility. The maximum etching error of the depth is 10-80nm, which is receivable with tolerance analyze in our design. The MDOE has 70mm diameter, and uniform illumination area is an Φ600μm spot. With using expanding 1.064 μm beam, the smoothing pattern in focus plane is measured. The result shows that the TPE is about 19%. It is believable that with the influence by the interaction of second hot electron and time domain smoothing this result is acceptable.
Indirect-drive Inertial Confinement Fusion(ICF) system has two requests: first, it requires incident beam to focus on a small spot with very low circular side-lobe around the edge of the hole; second, when it continue to transmit onto the wall of cavity, it requires uniform illumination. A two-step iteration algorithm aiming at two positions of this system is proposed to match these two requests with using Pure Phase Plate (PPE). Our results show that the circular side-lobe near the target hole has been depressed to about 10-11 W/cm2, and the beam has small top modulation on the target wall.
We report experimental generation of nonclassically correlated photon pairs from collective emission in a room temperature atomic vapor cell. The nonclassical feature of the emission is demonstrated by observing a violation of the Cauchy-Schwarz inequality. Each pair of correlated photons are separated by a controllable time delay up to 2 microseconds. This experiment demonstrates an important step towards the realization of the Duan-Lukin-Cirac-Zoller scheme for scalable long-distance quantum communication.