Nonlinear and bistable behavior of an ultrahigh-Q GaAs photonic crystal nanocavity

Abstract

The authors investigate the nonlinear and bistable behavior of a high-Q GaAs photonic crystal heterostructure nanocavity, side coupled to a line-defect slab waveguide. The observations agree well with a model incorporating the relevant nonlinearities. The power threshold for bistable behavior is at least one order of magnitude lower than what is reported so far.

Spontaneous emission spectrum of a two-level atom in a very-high-Qcavity

“…Q factors as high as 10 10 have been reached in the microwave domain [11], which is ten times better than the Q factor of the transition between the considered Rydberg states. In the field of solid-state optical microcavities, Q's above 10 8 have been achieved for silica microspheres [12] or microtoroids [13], whereas impressive progress has been recently witnessed for semiconductor based cavities such as micropillars [14], microdisks [15] or photonic crystal cavities [16]. On the emitter side, a radiative-lifetime limited emission linewidth has been observed for single semiconductor quantum dots at low temperature under resonant pumping conditions [17].…”

Oscillatory dynamics in nanocavities with noninstantaneous Kerr response

“…However SP and so-called weak turbulence occurs also in the opposite (say short cavity) limit, where the delay can be averaged out to end up with a differential mean-field model [2]. This regime becomes important nowadays where nano-cavities are employed for many modern photonic applications [16], including bistability [17], demonstrated in photonic crystal (PhC) membranes which offer great flexibility of design as well as high nonlinear performances in semiconductors [18][19][20][21][22][23][24][25]. In these cavities, transverse effects are absent and their dimensions are so small that the response time of the medium can be much larger than the light transit time in the cavity, yet being comparable with the photon lifetime which is strongly enhanced on account of the large quality factor Q. SP in such nano-cavities has * andrea.armaroli@unife.it been recently predicted, owing to the free-carrier dispersion induced by two-photon absorption [13].…”

Silicon photonic devices for mid-infrared applications

“…However, multiphoton absorption is unlikely at our wavelength range, as at least 4 photons are needed to overcome the Si bandgap energy. Furthermore, in our case the bistability is due to a redshift of cavity resonance with increasing power, which narrows down the possible origins of the nonlinearity to thermal effects and χ3 effects [35,36]. Thermal effects occur when light is absorbed into the cavity, changing the temperature of the cavity and hence the refractive index through the thermo-optic effect, resulting in a red-shift of the cavity resonance in the case of Si (thermo-optic coefficient of 1.8×10 -4 K -1 ).…”

“…We performed time domain measurements in order to separate these effects and established that our nonlinearity was primarily thermal [35,36,38]. By modulating the input laser signal with a sine wave and looking for distortion in the output signal [35,38] due to bistablity, we were able to establish that 200 kHz was the modulation frequency at which all bistability-induced distortion disappeared, indicating that instantaneous χ3 effects could not be the cause of our bistability [11]. The corresponding thermal time constant, 5 µs, is also consistent with finite-element modeling of thermal effects in our cavities.…”