摘要:

The nonlinear optical Kerr effect, acting on optical pulses in fibres, creates spectral sidebands and noise correlations between these sidebands. The reduction of photon-number fluctuations of these pulses below the shot-noise limit by spectral filtering is well established in the anomalous dispersion regime which allows for soliton formation. Here it is demonstrated that a significant quantum-noise reduction with spectral filtering can also be reached for pulses in the normal dispersion regime. The filter function was optimized and the power dependence of the noise reduction was investigated. The best squeezing result is (1.2 ± 0.2) dB (corresponding to (2.6 ± 0.7) dB inferred for 100% detection efficiency).

ISSN:0950-0340    

DOI:10.1080/09500349808230495

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The steady-state population behaviour in a laser driven V-type system has been analysed. The effects of spontaneous emission-induced coherence and of the relative phase of the two coherent driving fields are considered in detail. A large and unexpected population inversion is found on one of the optical transitions due to these coherent effects.

ISSN:0950-0340    

DOI:10.1080/09500349808230496

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

New methods for the production of blazed relief grating profiles using grating masks with either binary or harmonic transmittance have been developed. These methods are based on the recording of a scanning wave, properly modulated by a mask, through a grating period into photoresist. The applicability of the gratings produced by this method would be especially in the infrared or near-infrared wavelength regions in the reflection mode. These methods have been theoretically analysed and the principal ideas of the methods were experimentally verified.

ISSN:0950-0340    

DOI:10.1080/09500349808230497

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The angular distributions of the intensity of reflected radiation of thin films of amorphous silicon (a-Si) on thick transparent parallel-sided substrates illuminated with a light beam of finite diameter were fitted with theoretical dependences taking into account the optical inhomogeneity over the film thickness. This inhomogeneity was described by the valuesnf, αf,nband αbof the real part of refractive index and absorption coefficient at the surface of the film. The investigated film was also characterized by the values of the real part of the refractive index and the absorption coefficient averaged over its thickness namelyñandαrespectively. Values of the parameters determined in different experiments (both side sample illumination and different polarities of light) are consistent. For the investigated a-Si,nb, <nf<ñand α >α> αf.

ISSN:0950-0340    

DOI:10.1080/09500349808230498

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

In this paper we present one method for the characterization of the spatial light modulators (SLMs) of a real-time Vander Lugt type of correlator. This correlator uses two SLMs: one to introduce the scene and a second to introduce the frequency‐matched filter. The SLM characterization methods arein situ, that is in the correlator set‐up. Illumination conditions are different for each SLM, and consequently different characterization techniques must be used in each case. For the characterization of the scene SLM a diffraction method is used, while for the characterization of the filter SLM an interferometric technique is more convenient. Finally, we take into account the operating curves of scene and filter SLMs in the design of the filter in order to optimize the correlation peak.

ISSN:0950-0340    

DOI:10.1080/09500349808230499

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

In a one-atom micromaser, the expression for the density matrix of the cavity field without the rotating-wave approximation (RWA) is derived using a perturbation method. The phase evolution of the cavity field is investigated without the RWA, and the results are compared with those within the RWA. It is shown that the virtual-photon processes make the symmetric phase distribution in the RWA asymmetric and cause additional quantum oscillation, which indicate the field's phase fluctuation and frequency shift. Virtual photons also cause an extra phase distribution to the field which is initially in a vacuum state. The unique characteristic of the phase properties in the course of forming a photon-number state is investigated. Other new phenomena such as the undamped oscillation of the phase variance against the injected atomic number are found.

ISSN:0950-0340    

DOI:10.1080/09500349808230500

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

First-order nonspecular effects for Gaussian beams reflected on the first interface of a system formed by two interfaces of isotropic materials are studied. The complex lateral displacement is analytically determined and the validity of the approximations made is analysed. It is shown that the lateral displacement is independent of the beam waist and the approximation results suitable even for very narrow beams near Brewster's condition. With a dielectric-metal-dielectric configuration (Kretschmann's) and under resonance conditions, lateral displacements of up to 25% of the beam width can be obtained.

ISSN:0950-0340    

DOI:10.1080/09500349808230501

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A set of general formulae for paraxial ray tracing in inhomogeneous media are derived, which can be used together with the aberration formulae by Sands for the first- and third-order analyses of inhomogeneous lenses of all kinds of gradient function. The choice of an optimum step size for paraxial ray tracing and aberration integration is discussed, and it is shown that results with good accuracy can be obtained with a relatively large step size and very economic computing effort, even for complex gradient functions such as the tapered hyperbolic secant.

ISSN:0950-0340    

DOI:10.1080/09500349808230502

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Recently it was predicted that addition of spherical aberration to a focusing system with a small Fresnel number can increase the value of the maximum intensity on the optical axis. In this paper we report experiments which confirm this prediction. To this end we have measured the three-dimensional intensity distribution in the focal region of a lens with spherical aberration. We also show that this effectcannotbe used to increase the intensity at a fixed distance from the lens.

ISSN:0950-0340    

DOI:10.1080/09500349808230503

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

We present a detailed theory of a two-photon micromaser and study the properties of the photon field in this system. The Hamiltonian of twophoton processes is obtained by an exact unitary transformation from that of a three-level atom interacting with a single-mode field. We discuss trapping states and the realization of a photon number state.

ISSN:0950-0340    

DOI:10.1080/09500349808230504

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor