Silicon photonics has traditionally focused on near infrared wavelengths, with tremendous progress seen over the past decade. However, more recently, research has extended into mid infrared wavelengths of 2 μm and beyond. Optical modulators are a key component for silicon photonics interconnects at both the conventional communication wavelengths of 1.3 μm and 1.55 μm, and the emerging mid-infrared wavelengths. The mid-infrared wavelength range is particularly interesting for a number of applications, including sensing, healthcare and communications. The absorption band of conventional germanium photodetectors only extends to approximately 1.55 μm, so alternative methods of photodetection are required for the mid-infrared wavelengths. One possible CMOS compatible solution is a silicon defect detector. Here, we present our recent results in these areas. Modulation at the wavelength of 2 μm has been theoretically investigated, and photodetection above 25 Gb/s has been practically demonstrated.
Micro-ring modulators for use in high-speed telecommunication transceivers designed for silicon-on-insulator (SOI) for 2 μm wavelength operation are described and simulated with comparison to 1.55 μm. Device simulations show improved DC modulation performance due to the free-carrier effect described in the plasma dispersion relations which is stronger for longer wavelengths. WDM applications are described and simulated. Micro-ring modulator devices were designed and fabricated at A*STAR IME and are pending measurement.