RESUMEN
The mid-infrared (MIR) region is attracting increasing interest for on-chip synchronous detection and free-space optical (FSO) communications. For such applications, a high-performance electro-optical modulator is a crucial component. In this regard, we propose and investigate a graphene-based electro-absorption modulator (EAM) and microring modulator (MRM) using the suspended germanium waveguide platform. The modulators are designed for the second atmospheric window (8 to 12â µm). The incorporation of double-layer graphene on the suspended slot waveguide structure allows for the significant enhancement of light-graphene interaction, theoretically achieving a 3-dB bandwidth as high as 78â GHz. The EAM shows a calculated modulation depth of 0.022-0.045â dB/µm for the whole operation wavelength range. The MRM exhibits a calculated extinction ratio as high as 68.9â dB and a modulation efficiency of 0.59â V·cm around 9 µm. These modulators hold promise for constructing high-speed FSO communication and on-chip spectroscopic detection systems in the MIR atmospheric window.
RESUMEN
We propose an on-chip transverse magnetic (TM)-pass polarizer utilizing one-dimensional photonic crystals for multi-band operation. The TE0 modes in the 1550/2000nm wave band are suppressed by carefully selecting the pitch lengths of the nanoholes, leveraging the bandgap of the nanohole array. Conversely, the TM0 modes remain almost unaffected. The TM-pass polarizer employs a single-etched design on a standard 220â nm SOI platform and has a compact length of â¼ 17.9â µm. The simulated bandwidths (BWs) for polarization extinction ratios (PERs) > 20â dB and > 25â dB are about 210â nm and 195â nm for the 1550â nm wave band, and 265â nm and 240â nm for the 2000nm wave band. Moreover, the insertion losses (ILs) are â¼ 0.5/0.3â dB at wavelengths of 1550/2000nm, respectively. For the fabricated device, the measured BWs for PER > 20â dB and > 25â dB are evaluated to be larger than 100â nm for both 1550/2000nm wave bands. The measured ILs are 1/0.8â dB at wavelengths of 1550/2000nm. This straightforward and compatible design opens possibilities for the development of practical multi-band silicon photonic integrated circuits.