Ultrafast all-optical switching in semiconductor nonlinear directional couplers at half the band gap

Abstract

We demonstrate ultrafast, high throughput, all-optical switching in optimized, 2-cm-long, halfand full-beat-length nonlinear directional couplers operated at 1.55 pm, below half the band gap of Ga, s2Ala1sAs. The long device length allowed the elimination of nonlinear loss and resulted in a switching peak power and energy of 85 W and 65 pJ, respectively.

Ultrafast optical switching of photonic crystals

“…It is well-known that semiconductors have favorable properties for optical switching , hence they are excellent constituents for switchable photonic materials [121,122]. Moreover, their elevated refractive indices are highly advantageous to photonic crystals per se [22,25,33,34,105,123].…”

Three-photon absorption in ZnO and ZnS crystals

“…The implementation of such devices requires materials with low linear and nonlinear losses, high Kerr-type refractive nonlinearities and response times of a few picoseconds or less [11]. To search for materials which meet the above requirements, it has been suggested to target at semiconductors with their band gap at least twice the photon energy used (E g > 2 E photon ) avoiding optical absorption due to one-or two-photon transitions [12][13][14]. In this regard, wide-gap semiconductors are a suitable candidate; and ZnSe has been recently reported to be one of the promising candidates [15].…”

Mode-selective coupler for wavelength multiplexing using LiNbO3:Ti optical waveguides

“…However, the concept of directional couplers is also ideally suited to a planar geometry, which allows for the fabrication of couplers with tailored properties in various materials. Examples include broadband operation in a larger wavelength range for optical communications, fast electrical switching, polarization and mode-selective coupling, and intensity-dependent couplers that make use of nonlinear substrate material properties [5][6][7][8]. Besides semiconductors like silicon and III/V compounds, lithium niobate (LiNbO 3 ) is considered one of the most promising materials for integrated optical devices.…”

“…For this purpose, directional couplers may be used, which rely on the extension of the evanescent electric field outside the guiding core region [1][2][3][4][5][6][7][8]. If the evanescent fields of two waveguides that are close enough to each other overlap, light power can be coupled between the two interacting modes.…”