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We report the optical performance of a photonic receiver for laser communication applications. The receiver is composed of 14 × 12 grating coupler arrays. The received optical signal power will be combined electrically via germanium photodiodes. The photonic receiver is designed for 20-µm to 30-µm mode field diameter (MFD) input sources. To maximize the fill factor of the 200 µm × 200 µm light-receiving area, a design strategy has been proposed. (1) Grating couplers are customized for compactness. (2) Periods of grating couplers are designed to work as end-fire and back-fire grating couplers for the same incident angle of the input laser source. (3) Different widths of waveguides are routed to minimize cross talk. The photonic receiver is evaluated with a 10-µm MFD source. As a result of the evaluation, the receiving area considering the minimum efficiency of −10.5 dB is 95% of the designed area when illuminating 20-µm to 300-µm MFD laser sources.

Technological innovation with millimeter waves (mm waves), signals having carrier frequencies between 30 and 300 GHz, has become an increasingly important research field. While it is challenging to generate and distribute these high frequency signals using all-electronic means, photonic techniques that transfer the signals to the optical domain for processing can alleviate several of the issues that plague electronic components. By realizing optical signal processing in a photonic integrated circuit (PIC), one can considerably improve the performance, footprint, cost, weight, and energy efficiency of photonics-based mm-wave technologies. In this article, we detail the applications that rely on mm-wave generation and review the requirements for photonics-based technologies to achieve this functionality. We give an overview of the different PIC platforms, with a particular focus on hybrid silicon photonics, and detail how the performance of two key components in the generation of mm waves, photodetectors and modulators, can be optimized in these platforms. Finally, we discuss the potential of hybrid silicon photonics for extending mm-wave generation towards the THz domain and provide an outlook on whether these mm-wave applications will be a new milestone in the evolution of hybrid silicon photonics.

This paper presents the design and the performance analysis of a photonics-based beamformer for a spaceborne synthetic aperture radar implementing the scan-on-receive functionality. The considered device is a hybrid photonic integrated circuit composed of actives in InP and passives in TriPleX™, realizing the fast beamforming of three receiver beams out of 12 radio-frequency input signals and providing their simultaneous down-conversion to intermediate frequency. The analysis considers as main performance indicators the gain, the noise figure, and the dynamic range of the photonics-based beamformer, and demonstrates the device compliance to the application requirements and its suitability for satellite missions.

Due to the exponential growth of the bandwidth requirement for wireless communication systems, new frequency bands need to be utilized. For future 5G wireless networks, frequencies of 30 GHz to 90 GHz are considered, while for satellite and aircraft communications the sub-terahertz frequencies are considered. However, with increasing millimeter-wave frequencies (30 GHz – 300 GHz), high-speed electronic solutions become energy-inefficient, and alternative solutions are required. Photonics offers the bandwidth and a potentially seamless integration with the fiber-wireless technology (Fi-Wi) for 5G communications. Commercially available terahertz generators are often based on photonics, i.e., lasers, too. One particularly promising technique to generate the microwave or sub-terahertz signal is to use the comb generated by modulating a continuous-wave laser signal. By filtering two non-adjacent comb lines, a beat signal is generated that has a frequency that is an integer multiple of the electrical modulator driving signal. In this way, frequency multiplication is achieved using microwave photonics. Photodetectors and/or photomixers can then be used to convert the beat signal to a millimeter-wave. However, the energy-efficiency of these techniques – and how they compare to all-electronic solutions – has not been analyzed yet. In this paper we will present this energy-efficiency analysis, based on a silicon photonics implementation. Silicon photonics has the potential to miniaturize such systems, for ubiquitous and low-cost implementation. Silicon-based modulators, however, are not ideal phase modulators, and simulation tools need to incorporate this. The regimes, in terms of signal power and frequency, where photonics compares favorably over electronics, will be discussed.