Song Lan

Directional coupler with soliton-induced waveguides

We demonstrate a directional coupler that employs two waveguides induced by two mutually incoherent photorefractive solitons propagating in parallel at close proximity. Efficient coupling from one waveguide to the other is achieved for probe beams at wavelengths much longer than that of the solitons. We study the mutual coupling as a function of distance between solitons.

SECOND-HARMONIC GENERATION IN WAVEGUIDES INDUCED BY PHOTOREFRACTIVE SPATIAL SOLITONS

We propose and demonstrate experimentally second-harmonic generation in waveguides induced by photorefractive solitons, and show that the conversion efficiency is improved considerably.

Observation of two-dimensional multimode solitons.

We present the first experimental observation of (2+1) -dimensional multimode (composite) solitons. A single-hump component and a double-hump (dipole-type) component are jointly self-trapped as a composite soliton in a biased photorefractive crystal.

Spatial vector solitons consisting of counterpropagating fields.

We present the experimental observation of a spatial vector soliton formed by counterpropagation of coherent optical fields. This is to our knowledge the first observation of a vector soliton in which the induced waveguide (potential) is periodic in the propagation direction. This vector soliton induces a waveguide and a thick grating within the waveguide, which can be used as a tunable optical waveguide filter.

Self-trapping of one-dimensional and two-dimensional optical beams and induced waveguides in photorefractive KNbO(3).

We demonstrate self-trapping of one-dimensional and two-dimensional optical beams in a photorefractive KNbO(3) crystal. We study the waveguides induced by the self-trapped beams for prospective applications of tunable nonlinear frequency conversion in soliton-induced waveguides.

Optical parametric oscillation in soliton-induced waveguides

We demonstrate experimentally an optical parametric oscillator constructed in a waveguide induced by a photorefractive spatial soliton and show that the pumping threshold is reduced considerably.

Tuning of second-harmonic generation in waveguides induced by photorefractive spatial solitons

We demonstrate experimentally wavelength tuning of second-harmonic generation in waveguides induced by photorefractive solitons in a KNbO3 crystal. By rotating the crystal, we can attain as large wavelength tunability as in bulk but with considerable improvement in conversion efficiency and elimination of walk-off.

Directional coupler using soliton-induced waveguides

Summary form only given. Among the various types of spatial solitons, photorefractive solitons appear to be rather unique because they form at /spl mu/Watt optical power levels and the photorefractive effects are wavelength-sensitive, which means that a soliton formed by a low power beam can guide an intense beam of a less photosensitive wavelength. In this paper we propose and demonstrate experimentally that we can use two photorefractive soliton-induced waveguides to make a directional coupler.

Optical parametric oscillator in waveguides induced by photorefractive spatial solitons

Summary form only given. In an OPO, the threshold pump power is dependent on the signal gain per pass through the crystal. We demonstrate OPOs in waveguides induced by photorefractive solitons, and show that by using waveguiding, the gain is increased, leading to a greatly reduced threshold pump power for the same cavity loss. We build a doubly-resonant oscillator, in which the oscillation occurs at both the signal and the idler wavelengths. At the highest pump power, the output signal is slightly weaker than without the soliton. This is because on the reverse direction the signal and the idler transfer energy back to the pump beam, and the soliton waveguiding improves the efficiency of this reverse process as well. This issue can be readily resolved by use of a singly-resonant or a ring oscillator.

Grating filters in solitoninduced waveguides

We study experimentally the grating formed by two head-on colliding (counter-propagating) (1+1) D photorefractive solitons. Such gratings can be used as tunable waveguide filters in reconfigurable planar lightwave circuits