Wavelength Tunable Laser Diode Thermal Refractive Index Control
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Solution Overview
Problem
Current wavelength tunable semiconductor laser diodes face limitations in achieving a wide tunable range and efficient power management due to the reliance on carrier injection for refractive index modification, which increases optical loss and narrows the tunable wavelength range.
Innovation Solution
The semiconductor laser diode incorporates a sampled-grating distributed feedback (SG-DFB) region and a chirped-sampled-grating Bragg reflector (CSG-DBR) region with alternating gain and modifying regions along the optical axis, where heaters in the modifying regions adjust the refractive index to coincide gain and reflection peaks, enabling precise control of the emission wavelength through temperature modification rather than carrier injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If carrier injection is used to modify refractive index, then wavelength tuning is achieved, but optical loss increases and tunable range narrows
Solution Approach 1:
The patent replaces the electrical carrier injection mechanism with a thermal field mechanism. Heaters are integrated into the modifying regions to change the refractive index through temperature-dependent thermal effects, eliminating the need for carrier injection and its associated optical losses.
Solution Approach 2:
The patent changes the physical parameter used for refractive index modification from electrical carrier concentration to temperature. By controlling the temperature in modifying regions through integrated heaters, the refractive index is adjusted thermally, enabling wavelength tuning without the optical loss inherent in carrier injection methods.
2Adaptability or versatility
If carrier injection is used for wavelength tuning, then emission wavelength can be adjusted, but power consumption increases
Solution Approach 1:
The patent substitutes the high-power electrical carrier injection system with a thermal control system using integrated heaters. This thermal field approach consumes less power while achieving the same wavelength tuning function through temperature-dependent refractive index changes.
Solution Approach 2:
The patent transitions from electrical parameter control (carrier injection) to thermal parameter control (temperature). The integrated heaters provide precise temperature control in modifying regions, enabling wavelength tuning with lower power consumption compared to electrical injection methods.
3Adaptability or versatility
If heating is applied to modify refractive index, then wavelength tuning is achieved, but thermal influence on gain region may occur
Solution Approach 1:
The patent divides the laser diode structure into distinct functional regions: gain regions for light amplification and modifying regions with integrated heaters for refractive index control. This spatial segmentation allows independent optimization of each region, enabling thermal tuning without compromising gain region performance.
Solution Approach 2:
The patent applies heating locally only in the modifying regions where refractive index adjustment is needed, rather than heating the entire device. This localized thermal control achieves wavelength tuning while minimizing thermal influence on the gain regions, maintaining their optimal operating conditions.
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 enhances the tunable range of the emission wavelength by up to 38 nm and reduces power consumption by allowing for efficient thermal management, while maintaining low thermal influence on the gain region, thereby improving the laser diode's operational efficiency.
Implementation Method 1
Each of the modifying regions provides a heater to shift the gain peaks
Implementation Method 2
the CSG-DBR region shows a plurality of reflection peaks whose wavelength is adjusted by the heater provided in the space region
Implementation Method 3
an optical waveguide and a reflector. The optical waveguide includes a plurality of gain regions and a plurality of modifying regions alternately arranged to each other along the optical axis of the waveguide
Data Source
AI summary
A wavelength tunable laser diode (LD) is disclosed. The LD provides a SG-DFB region and a CSG-DBR region. The SG-DFB region shows a gain spectrum with a plurality of gain peaks, while, the CSG-DBR region shows a reflection spectrum with a plurality of reflection peaks. The LD may emit light with a wavelength at which the one of the gain peaks and one of the reflection peaks coincides. In the present LD, both the gain spectrum and the reflection spectrum are modified by adjusting the temperature of the SG-DFB region and that of the CSG-DBR region independently.