MoS2 hybrid integrated micro-ring resonator phase shifter based on a silicon nitride platform

High-speed mid-infrared graphene electro-optical modulator based on suspended germanium slot waveguides

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 12 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 78 GHz. The EAM shows a calculated modulation depth of 0.022-0.045 dB/µm for the whole operation wavelength range. The MRM exhibits a calculated extinction ratio as high as 68.9 dB and a modulation efficiency of 0.59 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.

InSb-based saturable absorbers for ultrafast photonic applications

Sb-related III-V compounds have recently gained great research interest owing to their excellent optical and electrical characteristics, which provide many possibilities in photonics and electronics. This study investigated the application of InSb films in ultrafast photonics. An InSb film was fabricated on the tapered zone of a microfiber, and its saturation intensity, modulation depth, and non-saturable loss were determined as 119.8 MW cm^-2, 23.5%, and 27.3%, respectively. The structure of the electronic band and density of states of InSb were theoretically calculated. Notably, mode-locked and Q-switched fiber lasers were realised by incorporating the InSb-microfiber device into two different Er-doped fiber cavities. In the Q-switching state, the narrowest pulse duration was measured as 1.756 μs with a maximum single-pulse energy of 221.95 nJ and a signal-to-noise ratio of 60 dB. In the mode-locking operation, ultrafast lasers with a high signal-to-noise ratio (70 dB), a pulse width as narrow as 265 fs and a repetition rate of 49.51 MHz were acquired. Besides, the second-harmonic mode-locked state was built with an output power of 13.22 mW. In comparison with the reported laser performance with 2D materials as saturable absorbers, the InSb-based mode-locked and Q-switched fiber lasers proposed herein exhibit better comprehensive performance.

A Review of Capabilities and Scope for Hybrid Integration Offered by Silicon-Nitride-Based Photonic Integrated Circuits

In this review we present some of the recent advances in the field of silicon nitride photonic integrated circuits. The review focuses on the material deposition techniques currently available, illustrating the capabilities of each technique. The review then expands on the functionalisation of the platform to achieve nonlinear processing, optical modulation, nonvolatile optical memories and integration with III-V materials to obtain lasing or gain capabilities.