Silisyum mikro-yuvarlarda optik anahtarlama

Silicon is a cheap and naturally abundant material and has contributed to the electronics revolution, which in turn has led to the foundation of separate fields known as silicon electronics and silicon photonics. In silicon photonics optical resonances are utilized, which are useful for various applications, i.e., optical components such as Fabry-Pérot resonators. However, with the passage of time focus has shifted to three dimensional optical resonators with microspheres being the prime example. Nowadays, optical resonances excited in microspheres are called whispering gallery modes (WGMs) and they can be beneficial for various photonics applications. In this work, a silicon microsphere, with a 1 mm diameter and a refractive index of 3.48, is used to excite the WGMs of the silicon microsphere by evanescent coupling with a silica optical fiber half coupler (OFHC). A near infrared CW laser with the central wavelength of 1472 nm is used for the excitation of the WGMs. Additionally, these WGMs are tuned with the help of a pulsed 405 nm Fabry-Pérot laser, which acts as pump laser to modify the refractive index of the microsphere. As the pump energy changes, an average red shift of 0.37 nm in the WGMs spectrum of the silicon microsphere is observed for 50% duty cycle of the pump laser, which leads to a refractive index change of ΔN = 8.75x10‑4 and a temperature change of ΔT = 4.70 K. This behavior can be explained by the thermo-optic effect (TOE) in silicon. All-optical switching in time domain is also carried out for the WGMs of the silicon sphere, as the pump modulates the refractive index of silicon, the resonant peaks are observed to be shifting in time domain. Overall, TOE tuning of the resonant spectra is shown to be beneficial for the all optical control of silicon resonators. This technique can be useful for applications in silicon photonics.