Hybrid Diode Laser Vernier Filter Layout for Lower ASE Noise
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing hybrid integrated diode lasers suffer from high total noise power at the output due to direct coupling of amplified spontaneous emission (ASE) noise from one gain section into the laser's output.
Innovation Solution
The location of at least one Mach-Zehnder Interferometer (MZI) is altered to be between the micro-ring resonators (MRRs) of the Vernier filter, ensuring even distribution of ASE noise filtering from both gain sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the output coupler MZI is placed in the prior-art position, then the laser cavity can be formed, but ASE noise from gain section 102B is directly coupled into the output, resulting in high total noise power
Solution Approach 1:
The Vernier filter comprising MRRs 108 and 110 is introduced as an intermediary element between the gain sections and the output coupler MZI. This intermediary structure provides selective filtering of ASE noise from both gain sections before the light reaches the output coupler, thereby reducing the total noise power at the laser output while maintaining the laser cavity functionality.
Solution Approach 2:
The Vernier filter is positioned upstream in the optical path, performing preliminary filtering of ASE noise from gain sections 102A and 102B before the light reaches the output coupler MZI. This preliminary action of noise filtering prevents the direct coupling of amplified spontaneous emission into the laser output, thereby improving noise performance.
2Reliability
If the MZI is moved to be between the MRRs of the Vernier filter, then ASE noise filtering is evenly distributed and total noise power is reduced, but the optical path configuration becomes more complex
Solution Approach 1:
The optical path is segmented into distinct functional zones: the Vernier filter section with MRRs 108 and 110 for noise filtering, and the output coupler MZI 112A for cavity coupling. By moving MZI 112A to be between the MRRs, the patent creates separate functional segments that perform noise filtering and cavity coupling independently, allowing even distribution of ASE noise filtering from both gain sections.
3Reliability
If the MZI position is altered to reduce noise, then RIN and optical phase noise are reduced, but the alignment requirements for longitudinal cavity mode with Vernier filter transmission maximum become more stringent
Solution Approach 1:
Phase control elements 104A and 104B are incorporated into the system to provide active feedback control for wavelength tuning. These phase control elements enable dynamic adjustment of the laser wavelength to maintain alignment between the longitudinal cavity mode and the Vernier filter transmission maximum, compensating for the more stringent alignment requirements introduced by the modified MZI positioning.
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 results in a lower total noise power at the output, leading to reduced relative intensity noise (RIN) and optical phase noise.
Implementation Method 1
Vernier filter 106 selects one of the laser cavity modes
Implementation Method 2
Vernier filter 106 comprising two tunable micro-ring resonators (MRRs) 108 and 110
Implementation Method 3
MZI 112A functions as a tunable cavity output coupler... MZI 112B functions as a light (power) combiner, combining the two output fields from MZI 112A
Implementation Method 4
Phase control elements 104A or 104B tune the wavelength of laser 100
Data Source
AI summary
An integrated diode laser having lower total noise power at its outlet is realized by positioning a Mach-Zehnder interferometer in the optical path between two micro-ring resonators of a Vernier filter.