Discrete Wavelength Tunable Laser Using Demux and DBR
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing tunable lasers require expensive and power-hungry electronic circuitry for full-range continuous tunability, particularly due to the need for digital-analog conversion (DAC) chips, and often necessitate complex driving circuits to switch between multiple semiconductor optical amplifiers (SOAs).
Innovation Solution
A discrete wavelength tunable laser design featuring a semiconductor optical amplifier (SOA) with a wavelength demultiplexer and tunable distributed Bragg reflectors (DBRs) that allows for wavelength switching without the need for multiple SOAs, using a simple driving circuit to operate the DBRs directly, thereby eliminating the requirement for DACs and complex driving circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If full range continuous tunability is implemented, then wavelength flexibility is improved, but cost and power consumption increase due to DAC chips
Solution Approach 1:
The continuous wavelength range is segmented into discrete wavelength channels defined by the AWG passbands. Instead of continuous tuning, the laser operates at specific discrete wavelengths corresponding to the AWG's spectral passbands, eliminating the need for DAC chips while maintaining practical tunability across the gain bandwidth.
Solution Approach 2:
The AWG acts as an intermediary component that defines discrete wavelength channels. The DBR grating reflects specific wavelengths that pass through the AWG's passbands, creating a natural discretization of the tuning range without requiring complex electronic control circuitry.
2Adaptability or versatility
If multiple SOAs are used to achieve wavelength switching, then wavelength tunability is improved, but device complexity increases due to complex driving circuits
Solution Approach 1:
Multiple wavelength selection functions are merged into a single SOA system. Instead of switching between multiple SOAs, one SOA is used with a DBR grating that can be tuned to reflect different wavelengths, combining the functions of multiple laser sources into a single device with wavelength-selective feedback.
Solution Approach 2:
The DBR grating's reflection wavelength is made dynamically可调 by changing the injection current, which alters the refractive index and thus the reflected wavelength. This dynamic tuning capability replaces the need for multiple static SOAs and complex switching circuits.
3Adaptability or versatility
If Sampled Grating DBR laser is used for wide tunability, then wavelength range is improved, but device complexity increases due to comb grating structure
Solution Approach 1:
The AWG serves multiple functions: it acts as a wavelength demultiplexer, defines discrete spectral passbands, and provides natural wavelength channel spacing. This multi-functionality eliminates the need for complex sampled grating structures while achieving the same wavelength selection capability.
Solution Approach 2:
Instead of using a complex sampled grating structure, the patent uses a simpler DBR grating combined with an AWG that copies the desired wavelength channel structure. The AWG's periodic structure creates the equivalent of a sampled grating's wavelength selection without the manufacturing complexity.
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 design achieves wavelength tunability without the need for multiple SOAs and complex driving circuits, reducing power consumption and costs while maintaining high tunability and stability across a wide range of wavelengths.
Implementation Method 1
an arrayed waveguide grating (AWG) configured to receive the output of the SOA and to produce a plurality of fixed spectral passbands within the gain bandwidth of the SOA
Implementation Method 2
one or more tunable distributed Bragg reflectors (DBR(s)) arranged to receive the outputs of the Demux, each tunable-DBR configured to select a reflective spectral band within the gain bandwidth of the SOA upon application of a bias current
Data Source
AI summary
A discrete wavelength tunable laser having an optical cavity which comprises: a reflective semiconductor optical amplifier (SOA); a demultiplexer (Demux) having a single input and a plurality of outputs, the Demux configured to receive the output of the SOA and to produce a plurality of fixed spectral passbands within the gain bandwidth of the SOA; one or more tunable distributed Bragg reflector(s) (DBR(s)) arranged to receive the outputs of the Demux, each tunable DBR configured to select a reflective spectral band within the gain bandwidth of the SOA upon application of a bias current; wherein the SOA forms the back end mirror of the optical cavity; the one or more tunable DBRs form the front end mirror of the optical cavity; and wherein the lasing channel of the discrete wavelength tunable laser is chosen by the overlap of the selected reflective spectral band of one of the one or more tunable DBRs with a fixed spectral passband of the Demux.