Optical Receiving Apparatus Cross Talk Suppression
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Solution Overview
Problem
In multi-channel integrated light receiving circuits for coherent optical communication, cross talk between signal and locally oscillated light is not effectively suppressed, leading to interference with the light receiving element monitoring the signal level.
Innovation Solution
An optical receiving apparatus with an optical waveguide substrate and 90-degree hybrid circuits that cause signal and locally oscillated light to interfere, along with strategically positioned signal and signal-light-level monitoring light receiving elements, and a housing that accommodates these components to minimize cross talk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the light receiving element array is disposed on the side face of the optical circuit to suppress cross talk, then cross talk between channels is reduced, but the locally oscillated light reflection and scattering still causes cross talk light to be received by the monitoring element
Solution Approach 1:
The patent positions the signal-light-level monitoring light receiving element on a different end face of the optical waveguide substrate (third or fourth end face) rather than on the same end face as the signal light receiving elements (second end face). This spatial separation in a different dimension prevents the monitoring element from receiving cross talk light that scatters in the optical waveguide, while still allowing it to receive the branched signal light for accurate level measurement.
2Ease of operation
If the monitoring light receiving element is positioned to receive branched signal light, then signal level monitoring is enabled, but reflected locally oscillated light scatters and diverges to be received by the monitoring element
Solution Approach 1:
The patent utilizes the third or fourth end face of the optical waveguide substrate for positioning the monitoring light receiving element, which is spatially separated from the second end face where signal light receiving elements are located. This dimensional separation ensures that the monitoring element receives only the branched signal light and not the scattered cross talk light from locally oscillated light reflection, enabling accurate signal level monitoring without harmful interference.
3Object-affected harmful factors
If traditional cross talk suppression techniques are used in multi-channel circuits, then channel isolation is improved, but they do not prevent cross talk light from reaching the monitoring element in coherent transmission systems
Solution Approach 1:
The patent extends cross talk suppression to coherent transmission systems by positioning the monitoring light receiving element on the third or fourth end face of the optical waveguide substrate, separate from the second end face where signal receiving elements are located. This spatial separation in a different dimension prevents scattered cross talk light from reaching the monitoring element, thereby maintaining both channel isolation and monitoring accuracy in coherent transmission systems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively suppresses the impact of cross talk light on the signal-light-level monitoring element, allowing for accurate measurement of the signal light level by positioning the monitoring element closer to the input end face and using light blocking structures to attenuate reflected light.
Implementation Method 1
an optical waveguide substrate in which optical waveguides configured to transmit signal light and locally oscillated light therethrough
Implementation Method 2
optical 90-degree hybrid circuits configured to cause the signal light and the locally oscillated light to interfere with each other whereby, the signal light is amplified
Implementation Method 3
signal light receiving elements configured to receive the interfering signal light and locally oscillated light; and a signal-light-level monitoring light receiving element configured to receive light branched from the signal light
Implementation Method 4
cross talk light generated by the locally oscillated light cannot be prevented from being received by the light receiving element for monitoring the signal light level
Data Source
AI summary
A housing accommodates an optical waveguide substrate, plural signal light receiving elements, and a signal-light-level monitoring light receiving element. Signal light and locally oscillated light are input into optical waveguides in the optical waveguide substrate from a first end face of the optical waveguide substrate. The plural signal light receiving elements are disposed aligned on a side of a second end face opposite to a side of the first end face of the optical waveguide substrate. The signal-light-level monitoring light receiving element is disposed on a side of a third end face or a fourth end face between the first end face and the second end face of the optical waveguide substrate and at a position closer to the first end face than to the second end face.