Tunable Emitting Device with Directly Modulated Laser and Ring Resonator
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Solution Overview
Problem
Existing solutions for optical access networks fail to achieve high transmission reach and dynamic extinction ratio while maintaining low complexity and cost, with current technologies either inducing low dynamic extinction ratio, increasing technology complexity, or requiring complex alignment and power-consuming compensation systems.
Innovation Solution
A tunable emitting device featuring an InP substrate with a directly modulated laser and a monolithically integrated passive ring resonator, utilizing p-doped re-growth and hydrogenation to reduce insertion losses and enable wavelength tuning, allowing for high optical budget and dynamic extinction ratio without complex feedback loops or precise alignments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an electro-absorption modulator is used to achieve high dynamic extinction ratio, then the extinction ratio is improved, but optical power is lost due to absorption in the modulator
Solution Approach 1:
The patent extracts the modulation function from a separate electro-absorption modulator component and integrates it directly into the laser diode structure, creating an externally-coupled laser diode system where the laser cavity serves as the modulation element, thereby eliminating the need for a separate absorbing modulator that causes power loss
Solution Approach 2:
The patent introduces an external optical cavity as an intermediary element that couples to the laser diode, enabling high dynamic extinction ratio through external coupling mechanisms rather than through absorption in a separate modulator, thus achieving modulation without the harmful absorption effect
2Loss of energy
If a passive taper section and different materials are used for laser and modulator to reduce power loss, then optical power loss is reduced, but technology complexity increases and device consumption increases
Solution Approach 1:
The patent merges the laser diode and optical cavity into a single integrated structure where the laser cavity serves dual purposes as both the light source and the modulation element, eliminating the need for separate modulator components and complex multi-material heterostructures
Solution Approach 2:
The laser cavity is designed to perform multiple functions simultaneously: it serves as the light generation medium, the optical resonance cavity, and the modulation element, thereby eliminating the need for separate specialized components for each function
3Reliability
If an integrated chirp managed laser with optical spectrum re-shaper is used to increase dispersion tolerance, then dispersion tolerance is improved, but transmission distance exceeds optical access network standards and wavelength tuning requires complex feedback loop
Solution Approach 1:
The externally-coupled laser diode system achieves dispersion tolerance through the natural properties of the external optical cavity and coupling geometry, without requiring active feedback control or complex wavelength tuning mechanisms
4Reliability
If a transmitter optical sub-assembly with hybrid integration of directly modulated lasers and free-space-optics is used to meet distance and DER requirements, then transmission performance is improved, but module packaging complexity increases due to precise alignment requirements
Solution Approach 1:
The patent merges the laser diode and external optical cavity into a single integrated unit with fixed geometric relationships, eliminating the need for complex alignment procedures and reducing packaging complexity while maintaining high transmission performance
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 solution enables efficient data transmission over 40 km of single mode fiber with an extinction ratio higher than 6 dB and high output power, reducing complexity and power consumption, and is compatible with existing packaging solutions like TO-can modules.
Implementation Method 1
said passive ring resonator having a resonance amongst several ones that is used for filtering a zero level induced by the data modulation
Implementation Method 2
carrying out a p-doped re-growth both in the active and passive sections of the InP substrate followed by a hydrogenation of the passive section of the InP substrate
Data Source
AI summary
An emitting device is intended for delivering photons with a chosen wavelength. This emitting device includes an InP substrate with a directly modulated laser arranged for generating photons modulated by a non-return-to-zero modulation to produce data to be transmitted, a passive ring resonator monolithically integrated with the directly modulated laser and having a resonance amongst several ones that is used for filtering a zero level induced by the data modulation, and a tuning means arranged along the directly modulated laser and/or around the ring resonator to tune the photon wavelength and/or the ring resonator resonance used for filtering.