Thermoopic type variable optical attenuator and array type variable optical attenuator using this

Abstract

A thermooptic type variable optical attenuator applicable to an array type variable optical attenuator that realizes a low cross talk between adjacent waveguide arrays. The thermooptic type variable optical attenuator (100), using an optical material having a negative thermooptic effect, comprises a multi-mode optical propagation unit (3) provided between single-mode optical waveguides (1, 8) via tapers (2, 7), a heating thin-film heater (4) provided above the multi-mode optical propagation unit (3) so as to be inclined an angle beta to the optical propagation direction of a first optical waveguide (50), and a second optical waveguide (9) optically coupled with the side surface (3S1) of the multi-mode optical propagation unit (3) and inclined an angle 2beta to the optical propagation direction of the first optical waveguide (50).

Description

technical field [0001] The present invention relates to a thermo-optical variable optical attenuator capable of adjusting the intensity of optical signals for each channel in the fields of large-capacity multi-channel optical communication systems and optical measurement systems, and an array type variable optical attenuator using the same. Attenuator. Background technique [0002] In recent years, with the rapid popularization of networks, as one of attempts to increase the transmission capacity of optical communication networks, wavelength division multiplexing (WDM) that multiplexes a plurality of optical signals of different wavelengths on one optical fiber WDM: Wavelength Division Multiplexing) method is put into practice. In WDM systems, the use of optical amplifiers (for example, erbium-doped fiber amplifiers: EDFA) is essential, but usually due to the wavelength dependence of the gain of optical amplifiers, it will cause receiver saturation or S / N ratio deterioratio...

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Problems solved by technology

In addition, the excited higher-order mode lights φ1 and φ2 diffuse toward the periphery of the multimode optical waveguide 23, causing light leakage, and as a result, the output optical power (P11) of the single-mode optical waveguide 27 is attenuated (that is, P11<P10)

[0010] When more than 20 of the thermo-optical variable optical attenuators are arranged in parallel to form an array type variable optical attenuator, the light leaked from each multimode waveguide is coupled with the adjacent waveguide, resulting in a difference in the amount of light attenuation. Variable range and poor crosstalk between adjacent waveguides (for example, when the distance between adjacent waveguides is 250μm, the crosstalk is about -34dB)

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