Relaxation of the alignment tolerances of a 1.55-mum extended-cavity semiconductor laser by use of an intracavity photorefractive filter

Commercial grating-tuned single-mode extended-cavity semiconductor lasers (ECLDs) can be tuned over 100 nm near 1.55mum . This continuous tuning with no mode hopping requires delicate factory adjustments and high mechanical stability so that the wavelength precision is kept as high as possible and the mismatch between the lasing wavelength and the wavelength of minimum loss remains as small as possible. The addition of a photorefractive crystal inside the cavity creates an adaptive spectral filter that decreases the loss of the lasing mode and thus enhances its stability. For what is to our knowledge the first time, we demonstrate the extension of the available wavelength-mismatch range without mode hopping by the addition of a CdTe photorefractive crystal inside the cavity of a single-mode grating-tuned ECLD.     

Laser mode manipulation by intracavity dynamic holography: Application to mode selection

Intra-cavity dynamic holography is proposed as a self-adaptive, easy to set up technique for efficient laser mode manipulation. A first implementation is presented here as a longitudinal mode selector providing a spectacular spectral narrowing in linear laser cavities operating both in the pulsed and the cw regimes. Received: 12 April 1999 / Published online: 24 June 1999     

High-efficiency single-mode Raman generation in a liquid-filled photonic bandgap fiber

Single-spatial-mode Raman generation in an ethanol-filled photonic bandgap fiber is demonstrated. Due to the limited bandwidth of the fiber, the generation is limited to the first Stokes order only, allowing high generated power without any visible decrease of the conversion efficiency. The realization of these two key properties opens the way to the realization of optimized compact nonlinear wavelength converters that will accommodate a large variety of usable liquids.     

The TEM101 mode laser beam—A powerful tool for optical levitation of various types of spheres

We point out in this paper that a TEM¹₀₁ mode laser beam is convenient to stably levitate either solid or hollow dielectric spheres or metallic ones. Except a sufficient incident flux, there is no stability condition required to levitate solid transparent spheres having a refractive index larger than the one of the surrounding medium. According to the beam and sphere diameters, the equilibrium position will be centered on the beam axis or off-axis. In the case of hollow dielectric or metallic spheres, the lateral stability requires specific conditions on sphere and beam diameters. These conditions are discussed and then experimentally shown by performing optical levitation of these various kinds of spheres either in vertical or in horizontal beams.     

Optical levitation by means of two horizontal laser beams: A theoretical and experimental study

Stable optical levitation of transparent solid glass spheres has been demonstrated using two horizontal TEM00 laser beams. The experimental results agree with a theoretical calculation which gives the value of the lateral force pushing the sphere towards the region of maximum light intensity and maintaining it on the axis of the beam.