Low-power all-optical switching in active semiconductor chirped periodic structures

Area of Science:

• Optoelectronics
• Semiconductor physics
• Nonlinear optics

Background:

• All-optical switching in semiconductor periodic structures is crucial for high-speed optical communication.
• Tuning spectral range and switching power are key challenges in device optimization.
• Spatial chirp, a variation in grating period, has not been fully explored for its impact on all-optical switching.

Purpose of the Study:

• To investigate the impact of spatial chirp in built-in gratings on all-optical switching performance.
• To quantify the effects on spectral range and switching power.
• To explore the potential for low-power, high-performance optical switching devices.

Main Methods:

• Theoretical analysis of active semiconductor periodic structures with spatially chirped gratings.
• Numerical simulations to model optical signal propagation and switching behavior.
• Parameter variation to study the influence of grating period linearity.

Main Results:

• A mere 0.24% linear variation in grating period nearly triples the spectral range for low-power switching.
• Upward-switching power at the onset of bistability is reduced by two orders of magnitude, falling below 10 nW.
• Optimal performance is achieved with optical signals on the long-wavelength side of the stop band, propagating with increasing grating period.

Conclusions:

• Spatial chirp is a highly effective parameter for enhancing all-optical switching in semiconductor periodic structures.
• The findings pave the way for developing ultra-low-power, wide-spectral-range all-optical switches.
• Prediction of multiple bistable hystereses in devices with significant spatial chirp warrants further experimental investigation.