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Materials with Magnetic-X Effects
Published in Chen Wu, Jiaying Jin, Frontiers in Magnetic Materials, 2023
For the magneto-optical modulator, the polarization plane of light rotates through the magneto-optical materials under the excitation of magnetic field to modulate the signal light beam. Generally, the magneto-optical modulator consists of polarizers, magnetic field generator, magneto-optical material, together with the analyzer. The magneto-optical modulators have found wide applications in modulating TV signals, as well as diverse optical detection systems for both civil and military applications. The Ce/Ga co-doped Gd3Fe5O12 single crystal thin film via improved edge-defined film-fed growth method exhibits a Faraday rotation angle as high as ~103 Deg/cm with improved optical transmittance (Liu et al., 2021). Through special intracavity power-modulator of a Nd:YVO4 using the TGG magneto-optical effect, the transmittance of the cavity changes periodically by changing the magnetic intensity, and the output power can also be modulated (Liu et al., 2020).
Photonic Integrations of Near-Infrared Indoor Optical Wireless Communications
Published in Ke Wang, Indoor Infrared Optical Wireless Communications, 2019
The optical modulator is a device to modulate the light signal according to the applied electrical signal. In traditional optical communication systems using discrete components, optical modulators are usually realized using LiNbO3 through the electro-optic effect. However, silicon does not have the electro-optic effect, and hence, other principles need to be explored to realize silicon photonic integrated optical modulators.
Optical Devices for Photonic Signal Processing
Published in Le Nguyen Binh, Photonic Signal Processing, 2019
Modulation efficiency is the most important property of all types of optical modulators. For analog systems, the linearity of the transfer function is critical that is the incremental change determining the mall signal and distortion of the output signals. While in digital systems the ON–OFF extinction ratio and the required voltage swing, modulation efficiency is determined by the transfer function of the modulator, which, in turn, determines the design of the modulators, the waveguide confinement of the modes, and the traveling wave electrodes.
The enhanced phase modulation ability of optical modulator based on bi-layer graphene-silicon waveguide
Published in Journal of Modern Optics, 2018
Feng Zhou, Wei Du, Jiefang Zhang
In the past few decades, we have seen a rapid development of computer and communication technology in response to the increasing demand for information. In the field of short distance communication, with the chip size decreasing constantly and speed increasing ceaselessly, conventional copper-made interconnects have confronted a series of bottlenecks such as intensification of parasitic capacitance and limited transmission bandwidth (1,2). However, the emergence of the optical interconnects may provide an ideal substitution to the conventional copper-made interconnects due to its particular advantages, namely low cross talk between different signals, large transmission bandwidth, low fabrication costs and compatibility with CMOS technology (1,2). The key component of optical interconnect is the optical modulator (2) which can be used to process real-time signal with different wavelengths, therefore an optical modulator featuring compact size, high modulation speed, large modulation depth and low energy consumption will be much appreciated in the application of optical devices.
Analysis of the dual-parallel Mach–Zehnder modulator-based equivalent phase modulation
Published in Journal of Modern Optics, 2018
Microwave photonics is an interdisciplinary area of optics and electronics, which can realize some functions that are complex or even impossible to be directly implemented in the radio-frequency (RF) domain (1–3). To connect the optical world and the electronic world in microwave photonic systems, the optical modulator is the key device. Many different kinds of optical modulators (4–8), such as phase modulator (PM), intensity modulator (IM), polarization modulator (PolM), etc., have been proposed to fulfil different kinds of applications. In order to implement even more complicated functions, optical modulators with more complicated structures are fabricated. For example, two IMs and a PM are integrated together to form a dual-parallel Mach–Zehnder modulator (DP-MZM), which is also called IQ modulator because it can realize optical IQ modulation under special bias points (9). There is another kind of optical modulator called dual polarization binary phase shift keyed (DP-BPSK) modulator, which consists of two IMs and a 90° polarization rotator. The DP-BPSK modulator is designed for DP-BPSK modulation format in 40 Gbps optical transmission networks, but it also has numerous applications in microwave photonics (10,11). A more complicated optical modulator is the dual polarization quadrature phase shift keyed (DP-QPSK) modulator, which is designed for DP-QPSK modulation format in 100 Gbps optical transmission networks, mainly consisting of two DP-MZMs and a 90° polarization rotator. Because of its high integration and a large number of controllable parameters, the DP-QPSK modulator also finds many applications in microwave photonics (12,13).