Tunable DFB Laser Array With AWG Filter
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Photonic integrated circuits (PICs) with tunable lasers face challenges in achieving wide spectral range wavelength tuning without excessive temperature changes, which can lead to reduced laser output power and reliability, especially for DFB lasers.
Innovation Solution
The use of an arrayed waveguide grating (AWG) with pairs of distributed feedback (DFB) lasers on a substrate, where the AWG's free spectral range (FSR) allows for selective wavelength tuning by adjusting the substrate temperature, enabling output of multiple wavelengths with manageable temperature changes, and fine-tuning with heaters to maintain performance within a narrow temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If wavelength tuning is achieved by changing the temperature of the tunable laser over a wide range, then the spectral range or band is extended, but the junction temperature exceeds the reliable operation limit and laser output power drops
Solution Approach 1:
The patent divides the wavelength tuning function into two independent parts: (1) coarse wavelength selection through AWG passband filtering, and (2) fine wavelength adjustment through small temperature changes of the DFB laser. This segmentation allows the laser to operate within a narrow, safe temperature range while still achieving wide spectral coverage through the AWG's multiple passbands.
Solution Approach 2:
The AWG acts as an intermediary between the laser and the output, providing wavelength selection through its passbands. The AWG's temperature is controlled separately to tune the passband positions, while the laser temperature is kept stable for reliable operation. This intermediary structure decouples the wavelength tuning function from the laser's temperature stability requirement.
2Adaptability or versatility
If wavelength tuning is achieved by changing the temperature of the tunable laser, then the spectral range is extended, but the manufacturing cost increases due to extensive temperature tuning requirements
Solution Approach 1:
The patent segments the temperature control function: the AWG substrate temperature is controlled for coarse wavelength tuning across multiple passbands, while the laser temperature is maintained at a stable, narrow range for fine tuning. This reduces the overall temperature tuning complexity and manufacturing cost compared to tuning a single laser over a wide temperature range.
Solution Approach 2:
The AWG structure provides multiple passbands that can be tuned to cover a wide spectral range, making the system universally applicable across different wavelength bands without requiring multiple separate laser devices. This multi-functionality is achieved through the AWG's ability to provide multiple selectable passbands.
3Reliability
If discrete transmitter and combiner components are used in WDM optical communication systems, then the system performance is maintained, but the manufacturing cost and complexity increase
Solution Approach 1:
The patent merges the transmitter laser and the combiner (AWG) into a single integrated device on a common substrate. The DFB laser and AWG are fabricated together, with the laser output directly coupled to the AWG input waveguide. This integration eliminates the need for separate discrete components and external coupling, reducing system complexity and cost while maintaining performance.
Solution Approach 2:
The integrated device serves multiple functions: the DFB laser generates the optical signal, the AWG performs wavelength multiplexing by combining multiple wavelengths, and the AWG also provides wavelength selection through its passbands. This multi-functional integration replaces what would traditionally require separate transmitter and combiner components.
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 approach allows PICs to output optical signals over a wide range of wavelengths with minimal temperature adjustments, improving reliability and reducing manufacturing costs by eliminating the need for extensive temperature tuning of individual lasers.
Implementation Method 1
an arrayed waveguide grating having input waveguides, a first dielectric slab, a second dielectric slab, intermediate waveguides extending between the first and second dielectric slabs
Implementation Method 2
a first distributed feedback laser configured to supply a first optical signal having a first wavelength and a second distributed feedback laser configured to supply a second optical signal having a second wavelength
Implementation Method 3
a thermoelectric cooler coupled to the substrate and configured to adjust a temperature of the substrate
Data Source
AI summary
Pairs of distributed feedback (DFB) lasers are provided on a substrate. An arrayed waveguide grating (AWG) is also provided on the substrate having input waveguides, each of which being connected to a corresponding pair of DFB lasers. The wavelengths of optical signals supplied from each pair of DFB lasers may be spectrally spaced from one another by a free spectral range (FSR) of the AWG. By selecting either a first or second DFB laser in a pair and temperature tuning to adjust the wavelength, each pair of DFB lasers can supply optical signals at one of four wavelengths, pairs of which are spectrally spaced from one another by the FSR of the AWG. A widely tunable transmitter may thus be obtained.