MZI Ring Resonator Modulator for Linear Phase Control
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Solution Overview
Problem
Conventional Mach-Zehnder interferometer (MZI) modulators using ring resonators face limitations due to their nonlinear phase response, which hinders their application in coherent phase modulation, while silicon photonics-based MZMs are inefficient and occupy a large portion of the chip due to long modulator waveguides.
Innovation Solution
A novel Mach-Zehnder interferometer ring resonator modulator (MZIRRM) structure with ring resonators and phase tuners is introduced, where the ring resonators are adjusted to resonate at the laser wavelength, ensuring equal round trip phase delays and enabling efficient phase modulation by differential driving of the ring resonators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional MZI modulators use long waveguide arms to achieve sufficient phase shift, then the phase modulation efficiency improves, but the device area increases significantly
Solution Approach 1:
The patent merges the advantages of ring resonators (compactness) with MZI structure (linearity) by integrating ring resonators into the MZI arms. The ring resonators provide strong light-matter interaction in a compact footprint while the MZI structure maintains linear phase response, resolving the contradiction between modulation efficiency and device area.
Solution Approach 2:
The patent transitions from conventional long waveguide phase modulation to ring resonator-based phase modulation, utilizing the resonant enhancement effect in the frequency domain. This dimensional change in the modulation mechanism allows achieving sufficient phase shift in a compact spatial footprint.
2Area of stationary object
If ring resonator modulators are used to reduce device area, then the compactness improves, but the phase response becomes nonlinear limiting coherent modulation
Solution Approach 1:
The patent combines ring resonators with MZI structure where the MZI's inherent linear phase response characteristic compensates for the nonlinear phase response of individual ring resonators. The differential phase modulation between the two MZI arms restores linearity while maintaining the compactness advantage of ring resonators.
3Power
If silicon photonics MZMs use long modulator waveguides to achieve low Vπ, then the phase shift voltage decreases, but the chip area occupied increases
Solution Approach 1:
The patent integrates ring resonators into the MZI arms to provide enhanced light-matter interaction. The ring resonators' resonant coupling creates strong phase modulation with much shorter interaction lengths, achieving low Vπ without requiring long waveguide arms, thus reducing chip area.
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
The MZIRRM achieves linear phase modulation suitable for multi-level phase and intensity modulation formats, such as BPSK, 4PSK, and QPSK, while being compact and efficient, overcoming the limitations of both silicon photonics and ring resonator modulators.
Implementation Method 1
the first and second ring resonators resonate at the laser wavelength making the first and second round trip phase delays equal substantially zero
Implementation Method 2
a first phase modulator capable of biasing the first ring resonator structure generating a first RF phase delay (φRF1) to the first sub-beam
Implementation Method 3
a splitter for splitting the input optical signal into first and second sub-beams; first and second waveguide arms extending from the splitter capable of supporting the first and second sub-beams
Implementation Method 4
an output combiner for combining the first and second sub-beams into an output modulated signal
Data Source
AI summary
In Mach-Zehnder interferometer (MZI) based modulators (MZM) input laser light comes in from one side, gets split into two MZI arms, then recombined at an opposite side. Each MZI arm may be phase or intensity modulated depending on the set phase offset, whereby coherent or intensity modulation may be performed which can later be de-coded by a receiver. Ring resonator type modulators (RRM) are compact; however, their phase response is nonlinear, normally limiting their application in coherent phase modulation. However, a combined MZI RRM overcomes the shortcomings of the prior art by providing a novel structure and driving scheme for use with semiconductor photonics that takes advantage of the compactness of ring modulators and the linearity of MZI by setting the ring resonators to resonate at the input laser light wavelength.