Discrete Wavelength Tunable Laser Using Demux and DBR
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Solution Overview
Problem
Tunable lasers based on the Digital Supermode DBR (DS-DBR) design require expensive and power-hungry electronic circuitry for control, particularly due to the need for digital-analog conversion (DAC) chips, making them impractical without gratings for primary control.
Innovation Solution
A discrete wavelength tunable laser design featuring a semiconductor optical amplifier (SOA), a wavelength demultiplexer (Demux) such as an Arrayed Waveguide Grating (AWG), and tunable distributed Bragg reflectors (DBRs) that select reflective spectral bands without the need for DACs, using a simple driving circuit to operate the DBRs directly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If Digital Supermode DBR (DS-DBR) design is used for tunable laser, then wavelength tunability is achieved, but expensive and power-hungry electronic circuitry (particularly DAC chips) is required
Solution Approach 1:
The patent extracts and removes the DAC chip from the system by using a passive optical grating for primary wavelength control. The DS-DBR structure is modified to work with a simple driving circuit that directly controls the refractive index of the grating regions without requiring digital-to-analog conversion, thereby eliminating the complex electronic circuitry while preserving wavelength tunability
Solution Approach 2:
The passive optical grating serves multiple functions: it provides the primary wavelength selection mechanism, replaces the need for DAC-based control, and enables direct control of the DS-DBR structure. This multi-functional component consolidates the wavelength control system and reduces electronic complexity
2Adaptability or versatility
If multiple SOAs are used to provide light for different wavelength channels, then full wavelength coverage is achieved, but device complexity and power consumption increase
Solution Approach 1:
The patent segments the wavelength selection function from the light generation function. A single SOA generates light across the gain bandwidth, while the passive optical grating and DS-DBR structure are segmented into multiple regions that selectively reflect different wavelength bands. This segmentation allows one SOA to serve multiple wavelength channels through optical filtering rather than requiring multiple SOAs
Solution Approach 2:
The passive optical grating acts as an intermediary between the single SOA and the multiple wavelength channels. It receives broadband light from the SOA and selectively directs different wavelength ranges to the appropriate DS-DBR regions, enabling wavelength multiplexing without requiring multiple active laser sources
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 allows for wavelength switching without multiple SOAs, reducing the complexity and power consumption of control electronics, enabling efficient operation of tunable lasers with solely semiconductor chips.
Implementation Method 1
a wavelength demultiplexer (Demux) having a single input and a plurality of outputs, the AWG configured to receive the output of the SOA and to produce a plurality of fixed spectral passbands
Implementation Method 2
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
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.