The paper "PHASAR-based WDM-devices: principles, design and applications" by Smit and van Dam provides a comprehensive overview of the principles, design, and applications of wavelength division multiplexing (WDM) devices based on optical phased arrays (PHASARs). PHASARs play a crucial role in multi-wavelength telecommunication links and networks, offering high transmission capacity and flexible network architectures. The authors discuss the operation and design of PHASARs, including focusing, dispersion, insertion loss, nonuniformity, bandwidth, and polarization dependence. They also explore methods to improve these properties, such as using birefringent waveguides, order matching, halfwave plates, dispersion compensation, and polarization splitters. The paper further delves into specific applications, including wavelength routers, multi-wavelength receivers, multi-wavelength lasers, and wavelength-selective switches. These devices are essential for advanced telecommunication systems, enabling efficient wavelength multiplexing and demultiplexing, and supporting complex network functionalities.The paper "PHASAR-based WDM-devices: principles, design and applications" by Smit and van Dam provides a comprehensive overview of the principles, design, and applications of wavelength division multiplexing (WDM) devices based on optical phased arrays (PHASARs). PHASARs play a crucial role in multi-wavelength telecommunication links and networks, offering high transmission capacity and flexible network architectures. The authors discuss the operation and design of PHASARs, including focusing, dispersion, insertion loss, nonuniformity, bandwidth, and polarization dependence. They also explore methods to improve these properties, such as using birefringent waveguides, order matching, halfwave plates, dispersion compensation, and polarization splitters. The paper further delves into specific applications, including wavelength routers, multi-wavelength receivers, multi-wavelength lasers, and wavelength-selective switches. These devices are essential for advanced telecommunication systems, enabling efficient wavelength multiplexing and demultiplexing, and supporting complex network functionalities.