DBR Laser Device Wavelength Stability
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Solution Overview
Problem
In laser devices used for optical fiber communications, increasing the drive current to enhance laser light output often results in a wavelength shift, making it difficult to maintain effective light modulation within the operation wavelength band of the ring assist optical modulator.
Innovation Solution
The laser device separates the functions of laser oscillation and amplification by using a distributed Bragg reflector (DBR) waveguide and a second gain waveguide, allowing independent current injection to increase light intensity without shifting the oscillation wavelength, thereby maintaining a constant wavelength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the drive current is increased to enhance laser light output, then the laser light intensity is improved, but the oscillation wavelength shifts making it difficult to maintain effective light modulation
Solution Approach 1:
The laser device is divided into two separate gain waveguides: a first gain waveguide (11) dedicated to laser oscillation and a second gain waveguide (12) dedicated to light amplification. This segmentation allows independent control of oscillation wavelength and output intensity, resolving the contradiction between enhancing light intensity and maintaining wavelength stability.
Solution Approach 2:
The first gain waveguide acts as an intermediary that generates stable wavelength laser light through oscillation, which then serves as the input for the second gain waveguide to amplify. This intermediary structure enables the second gain waveguide to increase output intensity without affecting the oscillation wavelength established by the first gain waveguide.
2Device complexity
If a single gain waveguide is used for both laser oscillation and amplification, then the device structure is simplified, but increasing current to enhance output causes wavelength shift
Solution Approach 1:
The single gain waveguide is segmented into two functionally distinct gain waveguides: the first gain waveguide for oscillation and the second gain waveguide for amplification. This segmentation resolves the conflict between structural simplicity and wavelength stability by creating a clear functional division that prevents current-induced wavelength shifts.
3Productivity
If current is increased in the gain waveguide to increase light output, then productivity is improved, but the transmission center wavelength shifts out of the modulator's operation band
Solution Approach 1:
The gain function is segmented into oscillation (first gain waveguide) and amplification (second gain waveguide), allowing the second gain waveguide to increase light output without affecting the oscillation wavelength, thus maintaining compatibility with the modulator's operation wavelength band.
Solution Approach 2:
The first gain waveguide serves as an intermediary that establishes the stable oscillation wavelength, enabling the second gain waveguide to amplify the light without causing wavelength shifts, thereby maintaining adaptability to the modulator's operation band while increasing productivity.
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 enables increased laser light intensity without wavelength shift, ensuring stable operation and effective light modulation by fixing the current to the first gain waveguide and increasing it in the second gain waveguide, thus preventing transmission center wavelength shifts.
Implementation Method 1
a distributed Bragg reflector (DBR) waveguide and a second gain waveguide, allowing independent current injection to increase light intensity without shifting the oscillation wavelength
Implementation Method 2
the first gain waveguide functions as a gain medium
Implementation Method 3
an antireflection film formed on a device end surface to which the second gain waveguide is connected
Implementation Method 4
the optical waveguides in the wavelength-selective reflection device reflect light having a predetermined wavelength from incident light to the optical waveguides
Data Source
AI summary
A laser device includes an optical semiconductor device formed of a compound semiconductor material; and a wavelength-selective reflection device including optical waveguides. Further, the optical semiconductor device includes first and second gain waveguides, a DBR waveguide formed between the first and the second gain waveguides, first and second electrodes to inject current in the first and the second gain waveguides, and an antireflection film formed on a device facet to which the second gain waveguide is connected. The optical waveguides in the wavelength-selective reflection device reflect light having a predetermined wavelength from incident light in the optical waveguides. The first gain waveguide is optically coupled with the wavelength-selective reflection device, so that a laser resonator is formed by the DBR waveguide and the wavelength-selective reflection device, and the first gain waveguide functions as a gain medium.