Group velocity and impedance matches are prerequisites for high-speed Mach-Zehnder electro-optic modulators. However, not all platforms can realize match conditions, restricting high-speed modulation in many practical platforms. Here we propose and demonstrate a general method to satisfy the group velocity and characteristic impedance matches by cascading fast-wave and slow-wave traveling wave electrodes on a thin-film lithium-niobate-on-insulator platform with a silica cladding. The effective group velocity can be flexibly adjusted by changing the ratio of fast-wave and slow-wave traveling wave electrodes. The radio frequency signal insertion loss at the boundary of the slow-wave and fast-wave electrodes is less than 0.1 dB. In addition, for a modulator of 6000 μm length, our simulation indicates an electro-optic response of over 100 GHz, surpassing what can be achieved with purely slow-wave or fast-wave electrodes that lack matching conditions. Our results will open many opportunities for high-speed electro-optic modulators in various platforms.
Dealing with the increase in data workloads and network complexity requires efficient selective manipulation of any channels in hybrid mode-/wavelength-division multiplexing (MDM/WDM) systems. A reconfigurable optical add-drop multiplexer (ROADM) using special modal field redistribution is proposed and demonstrated to enable the selective access of any mode-/wavelength-channels. With the assistance of the subwavelength grating structures, the launched modes are redistributed to be the supermodes localized at different regions of the multimode bus waveguide. Microring resonators are placed at the corresponding side of the bus waveguide to have specific evanescent coupling of the redistributed supermodes, so that any mode-/wavelength-channel can be added/dropped by thermally tuning the resonant wavelength. As an example, a ROADM for the case with three mode-channels is designed with low excess losses of <0.6, 0.7, and 1.3 dB as well as low cross talks of < − 26.3, −28.5, and −39.3 dB for the TE0, TE1, and TE2 modes, respectively, around the central wavelength of 1550 nm. The data transmission of 30 Gbps / channel is also demonstrated successfully. The present ROADM provides a promising route for data switching/routing in hybrid MDM/WDM systems.
Dispersion management is highly desired in various applications such as microwave photonics and optical communication, helping reduce the delay disorder and modulate the pulse profiles. In this paper, we propose a new concept of digitally-tunable dispersion management. and a digitally-tunable dispersion controller (DTDC) on silicon composed of optical switches and chirped multimode waveguide gratings (CMWGs) is demonstrated for the first time. All the CMWGs are identical and have the same dispersion value of D0 and dispersion ranging from 0 to (2N-1)D0 can be tuned with a step of D0 by switching the propagation path of light. More importantly, the DTDC is circulator-free. finally, a DTDC is realized with four stages of 2-mm-long CMWGs, enabling the dispersion tuning from 0 to 42.8 ps/nm with a step of 2.82 ps/nm.
Integrated modulators are essential components for optical sensing and communication applications. However, most efforts have been focused on infrared telecommunications wavelengths, with very little consideration for visible light applications. Here, we design an electro-optic (EO) modulator at 532 nm with the waveguides formed by SU8 polymer structures on the thin-film lithium niobate (LN). The simulation results show a low loss, high modulation efficiency, and large bandwidth simultaneously for the modulator. The predicted low loss is attributed to the LN etchless waveguide and high coupling efficiency, i.e., 93%, with the single-mode fiber theoretically using a SU8 edge coupler. The simulated low voltage-length product of 1.15 V · cm and a 3-dB-bandwidth of >120 GHz at a length of 5 mm are superior to any other modulator in the optical communication band. The modeling of the modulator proposed here shows great potential for visible light communications applications such as energy-efficient and large-capacity underwater wireless optical interconnects.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.