Methods and apparatuses for downconverting are provided. A dual-drive mach zehnder modulator (DDMZM) receives: a continuous wavelength optical signal, an input signal (microwave signal), and local oscillator tones. The DDMZM includes: first and second arms formed from optical waveguides which receive the optical signal, a first modulator that receives the input signal, and a second modulator that receives the oscillator tones. The input signal is modulated onto the optical signal propagating through the first arm to form a first modulated optical signal. The oscillator tones and third-order intermodulation products of those tones are modulated onto the optical signal propagating through the second arm to form a second modulated optical signal. The modulated optical signals are combined to form an output optical signal. The oscillator tones are spaced two folded bandwidths apart and centered within a spectrum of interest of the input signal.

A coplanar waveguide wire electrode structure and a modulator includes a metal electrode and an optical waveguide. The metal electrode includes ground electrodes and a signal electrode. Connecting arms are arranged on both sides of the signal electrode. The inner sides of the ground electrodes are provided with other connecting arms. The tail ends of the connecting arms of the signal electrode are provided with signal wire extension electrodes, and the tail ends of the connecting arms of the ground electrodes are provided with ground wire extension electrodes. A distance is provided between the signal wire extension electrodes and the ground wire extension electrodes. The optical waveguide passes through the spaces between the signal wire extension electrodes and the ground wire extension electrodes. By extending the metal electrode, the distance between the electrodes is actually shortened.

An electro-optical system having one or more electro-optical devices integrally formed within a substrate and associated methods are disclosed. An electro-optical system including an electro-optic switch is shown. An electro-optical system including an electro-optic modulator is shown. An electro-optical system including an optical resonator is shown.

An electro-optical system having one or more electro-optical devices integrally formed within a substrate and associated methods are disclosed. An electro-optical system including an electro-optic switch is shown. An electro-optical system including an electro-optic modulator is shown. An electro-optical system including an optical resonator is shown.

A velocity mismatch between optical signals and microwave electrical signals in electro-optic devices, such as modulators, may be compensated by utilizing different lengths of bends in the optical waveguides as compared to the microwave electrodes to match the velocity of the microwave signal propagating along the coplanar waveguide to the velocity of the optical signal. To ensure the electrode bends do not affect the light in the optical waveguide bends, the electrode may have to be rerouted, e.g. above or below, the optical waveguide layer. To ensure that the pair of optical waveguides have the same optical length, a waveguide crossing may be used to cross the first waveguide through the second waveguide.

An optical modulators is disclosed. The optical modulator includes a substrate, an optical waveguide formed on the substrate, a signal electrode formed on the optical waveguide via a first buffer layer and applying a modulation signal to the optical waveguide, and a bias electrode formed on the optical waveguide via a second buffer layer and applying a DC bias to the optical waveguide, the first buffer layer and the second buffer layer are formed in such a way that either one of the first buffer layer and the second buffer layer covers an end surface of the other one of the first buffer layer and the second buffer layer at a boundary part of the first buffer layer and the second buffer layer. Accordingly, an optical modulator with high reliability can be provided.

An electro-optical device includes an optical waveguide and an upper electrode provided on the optical waveguide, the optical waveguide is formed by turning back on a plane, the upper electrode has adjacent parts by turning back the optical waveguide, and an upper layer higher than the upper electrode between the adjacent parts includes a metal layer. Alternatively, an electro-optic device includes a plurality of Mach-Zehnder optical waveguides, wherein the Mach-Zehnder optical waveguide includes a first optical waveguide and a second optical waveguide, a first upper electrode is provided on the first optical waveguide and a second upper electrode is provided on the second optical waveguide, and an upper layer higher than the first upper electrode and the second upper electrode between the first upper electrode and the second upper electrode includes a metal layer. An electro-optic device is capable of suppressing electrical crosstalk between components and seeking wide frequency band.

An optical waveguide element includes: an optical waveguide having a ridge part and a slab part having a thickness less than the ridge part. The optical waveguide includes: a first waveguide having a first ridge with and a first slab film thickness; a second waveguide having a second ridge width and a second slab film thickness; a first intermediate waveguide connected to the first waveguide and having a third ridge width and the first slab film thickness; and a second intermediate waveguide connected to the second waveguide and having a fourth ridge width and the second slab film thickness. The first waveguide, the first intermediate waveguide, the second intermediate waveguide, and the second waveguide are arranged in this order; the second slab film thickness is larger than the first slab film thickness; and the third ridge width is larger than the fourth ridge width.

The optical device includes a substrate and an optical waveguide formed on the substrate, a protrusion portion is formed on the substrate adjacent to the optical waveguide. Accordingly, an optical device which can achieve further suppression of the light propagation loss and higher reliability is provided

An electro-optical device includes a substrate, an optical waveguide formed on the substrate, a buffer layer formed on the substrate which is provided so as to cover the optical waveguide and an electrode formed on the buffer layer, when viewed in a propagation direction of light, a side surface of the optical waveguide has at least one slope change point. An electro-optical device can reduce the driving voltage and provide the propagation loss of light.