Cascaded two-photon nonlinearity in a one-dimensional waveguide with multiple two-level emitters

We propose and theoretically investigate a model to realize cascaded optical nonlinearity with few atoms and photons in one-dimension (1D). The optical nonlinearity in our system is mediated by resonant interactions of photons with two-level emitters, such as atoms or quantum dots in a 1D photonic waveguide. Multi-photon transmission in the waveguide is nonreciprocal when the emitters have different transition energies. Our theory provides a clear physical understanding of the origin of nonreciprocity in the presence of cascaded nonlinearity. We show how various two-photon nonlinear effects including spatial attraction and repulsion between photons, background fluorescence can be tuned by changing the number of emitters and the coupling between emitters (controlled by the separation).Comment: 6 pages, 4 figure

STIMULATED RECOMBINATION AND THE DYNAMIC MOTT TRANSITION IN GaTe.

The dynamics of photoexcited carriers in direct gap semiconductors can now be measured directly by time-resolved spectroscopy using intense, ultra-short laser pulses. High carrier densities can be generated and the processes of carrier cooling and recombination can be investigated by measuring band-edge transient absorption and luminescence. At high carrier densities a Mott transition is expected to occur when the interparticle separation r//s congruent 2. 5 a//o , where a//o is the exciton radius, so that for lower values of r//s dramatic changes in the band-edge absorption spectrum are expected. We report measurements of the layered semiconductor GaTe. The chief interest in this material is, as with other III-VI semiconductors, the strong excitonic behaviour exhibited at low temperature

Métodos e sistemas para osciladores opto-electrónicos = Methods and systems for optoelectronic oscillators

NOVELTY - The method includes a system, which comprises oscillator resonant tunneling diodes with photoconductive region, diode laser, optical modulator structure, optical wave guide and electrical input port. The electrical input port accepts electrical control signal through electrical output port. The oscillator resonant tunneling diodes output electrical signals, where and optical signals are oscillated at a frequency related to electrical or optical control signals. USE - Methods for optoelectronic oscillators