Mode-hop free athermal laser with intracavity phase shifter
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing semiconductor lasers experience mode-hopping due to temperature fluctuations, which prior solutions fail to fully address, especially in photonic integrated circuits, leading to inefficient power usage and unsuitability for wavelength division multiplexing.
Innovation Solution
Integration of an intracavity phase shifter capable of continuous phase shift at a single wavelength over a large range, combined with a switchable optical cavity length configuration, allowing for phase adjustment to maintain output wavelength stability and prevent mode-hops, using components like Mach-Zehnder Interferometers and retroreflective phase shifters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If passive compensation materials with negative thermal coefficients are used in the laser cavity, then mode-hops are compensated for uniform temperature changes, but the solution cannot compensate for fluctuations within the laser cavity and has limited temperature operating range
Solution Approach 1:
The patent implements an active feedback control system that continuously monitors the laser wavelength and adjusts the cavity length in real-time to compensate for mode-hops. This feedback mechanism enables the system to adapt to both uniform temperature changes and fluctuations within the laser cavity, overcoming the limitations of passive compensation methods.
Solution Approach 2:
The patent transitions from static passive compensation to dynamic active control by using a movable mirror or tunable cavity element that can continuously adjust the cavity length. This dynamic adjustment allows the system to maintain wavelength stability across a wide temperature operating range and respond to real-time temperature fluctuations.
2Reliability
If the effective cavity length is changed to eliminate mode-hops, then the laser wavelength shifts continuously without mode-hops, but the large shift in operating wavelength makes it unsuitable for wavelength division multiplexing
Solution Approach 1:
The patent precisely controls the cavity length adjustment parameter to provide just enough compensation to eliminate mode-hops without causing large wavelength shifts. By carefully tuning the compensation magnitude, the system maintains wavelength stability suitable for wavelength division multiplexing while still preventing mode-hops.
3Reliability
If the entire packaged PIC is heated to a fixed temperature, then mode-hops are eliminated, but power consumption increases and the laser operates less efficiently
Solution Approach 1:
The patent applies local quality by implementing active feedback control only in the laser cavity region where mode-hops occur, rather than heating the entire packaged PIC. This localized approach eliminates mode-hops while minimizing power consumption and maintaining overall laser efficiency.
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 effectively eliminates mode-hops across a wide temperature range, maintaining stable output wavelength and reducing power consumption, making it suitable for applications like wavelength division multiplexing.
Implementation Method 1
Integration of an intracavity phase shifter capable of continuous phase shift at a single wavelength over a large range
Implementation Method 2
cavity designs that utilize materials with temperature coefficients of expansion to get an athermal response
Implementation Method 3
retroreflective phase shifters
Data Source
AI summary
Embodiments of the invention describe integrating a phase shifting component into a cavity of a laser. Said phase shifter is capable of a continuous phase shift at a single wavelength over a large range (where the maximum energy consumption of the phase shifting component does not scale with the phase shifting range). In other words, said phase shifter is used to form a configurable optical cavity length for a laser. Embodiments of the invention thus utilize a plurality of optical cavity lengths—including one or more optical cavity lengths to potentially shift the phase of the output optical signal, to maintain a laser cavity's output wavelength and avoid spatial mode-hops in the presence of fluctuations such as temperature drift or changes to the drive current of the laser.