摘要:
An optical waveguide (16, 18) is formed over a substrate, with an insulating planarization layer (30) formed adjacent the optical waveguide (16, 18) and level with the top of the waveguide (16, 18). A microwave transmission line (32a, b) is formed over the planarization layer (30) and overlies a top surface of the optical waveguide(16, 18). In this circuit, isolation of a microwave transmission line (32a, b) is provided by forming the line over a planarization layer (30) which fills the space adjacent to an optical waveguide structure (16, 18). The transmission line (32a, b) can then contact electrically the top surface of the waveguide structure (16, 18) but is isolated from the substrate which supports the waveguide (16, 18).
摘要:
This device is a broadband, electro-optic modulator comprising an exemplary coplanar waveguide (CPW) electrode structure on an exemplary Mach-Zehnder interferometer. The modulator is formed on a lithium niobate (LiNbO3) substrate that is etched so as to form ridges upon which a gold center electrode and two gold grounded waveguides are deposited upon a buffer layer of silicon dioxide (SiO2) to form a coplanar waveguide electrode structure having a waveguide mode for receiving an electrical signal propagating therethrough in a first direction with a second phase velocity to phase modulate an optical light in the optical waveguide at a frequency in the range from 0 Hz to substantially 40 GHz. The ridges formed by the etching of the substrate acts to lower the effective dielectric constant of the structure, and as the spacing between electrodes is increased, the overlap integral gets larger as the electrical field becomes more vertical, and better confined, and the intrinsic electrical loss coefficient is reduced and the electrical losses through the device become smaller requiring less voltage to modulate the optical signal.
摘要:
An electro-optic modulator for modulating a beam of electro-magnetic radiation having a beam path and a beam axis (A) is of a transverse type and comprises: a modulator element (3) that is positioned in the beam path, a housing (2) for receiving the modulator element (3), which housing (2) forms a resonant cavity, and a coupling device (4) for inputting modulating energy into the housing (2) such that a resonant standing wave is generated within the housing (2). The housing (2) comprises at least one sidewall (13, 14, 15, 16, 21, 22, 25, 26, 31, 32, 35, 36, 41, 42, 45, 46, 51, 52) that extends substantially parallel to the beam axis (A) over a length (L), wherein the at least one sidewall (13, 14, 15, 16, 21, 22, 25, 26, 31, 32, 35, 36, 41, 42, 45, 46, 51, 52) comprises a deformed portion (21b, 25b, 26b, 31b, 32b, 35b, 36b, 41b, 42b, 45, 46, 51b, 52b) such that in the resonant cavity a distance (di, d2, d3, d4, d5, ci, c2, c3, c4) between the sidewall and the beam axis (A) in a direction perpendicular to the beam axis (A) varies over at least a portion of the length (L) of the sidewall.
摘要:
An optical modulator comprises an optical input (2); an optical output (14); at least one optical path (6, 8) connecting the optical input (2) and output (14) and means (10, 28) for selectively changing the optical characteristic of a part of the at least one optical path in response to a control signal (Vmod) such as to modulate light passing along the optical path. The optical path further includes a structure (16) which slows the passage of light along the part of the optical path to enhance the modulation effect of the modulator for a given length of optical path. Preferably the structure (16) comprises a sequence of coupled resonator structures in which each resonator structure is defined by a pair of partially reflecting planes (16a, 16b) which define an optical resonator cavity within the optical parts.