Inverted Waveguide AWG for Optical Power Homogeneity
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Solution Overview
Problem
Conventional optical semiconductor apparatuses with integrated semiconductor laser devices of different emission wavelengths face high loss and reduced output efficiency due to the mismatch between the loss characteristics of arrayed waveguide gratings and the gain characteristics of semiconductor laser devices, particularly at the band edge, limiting the increase in optical power.
Innovation Solution
The optical semiconductor apparatus groups semiconductor laser devices into two groups and uses an arrayed waveguide grating to combine laser light beams from each group by different diffraction orders, with the input waveguides arranged such that their order is inverted with respect to the wavelengths they guide, thereby canceling out the wavelength dependence of the AWG and the active layers, reducing loss and increasing output efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an arrayed waveguide grating is used as the optical coupling unit to reduce loss, then the loss at the central wavelength is minimized, but the loss increases at wavelengths away from the central wavelength, particularly at the band edge
Solution Approach 1:
The semiconductor laser devices are divided into two groups: a first group with shorter wavelengths and a second group with longer wavelengths. Each group is coupled to the AWG through separate input waveguides, allowing independent optimization of coupling paths for different wavelength ranges.
Solution Approach 2:
The input waveguides are arranged in an inverted order: the first input waveguide (for shorter wavelengths) is positioned at a location corresponding to longer wavelengths in the AWG, while the second input waveguide (for longer wavelengths) is positioned at a location corresponding to shorter wavelengths in the AWG. This inversion compensates for the AWG's wavelength-dependent loss characteristics.
2Adaptability or versatility
If semiconductor laser devices with different emission wavelengths are integrated to create a wavelength-tunable light source, then the versatility of the optical semiconductor apparatus is improved, but the loss and reduced output efficiency increase due to the mismatch between AWG loss characteristics and semiconductor laser gain characteristics
Solution Approach 1:
Different input waveguides are assigned to different wavelength groups with specific arrangement positions optimized for their respective wavelength ranges. The first input waveguide handles shorter wavelengths with positioning optimized for that range, while the second input waveguide handles longer wavelengths with positioning optimized for that range, creating locally optimized coupling throughout the wavelength band.
Solution Approach 2:
The arrangement position of input waveguides is changed relative to their wavelength characteristics. By inverting the arrangement order, the system changes the spatial parameter of waveguide positioning to compensate for the wavelength-dependent loss parameter of the AWG, thereby improving output efficiency across the entire wavelength band.
3Power
If the power of the optical semiconductor apparatus is increased to improve output efficiency, then the optical power output is enhanced, but the power limit at the band edge restricts power over the entire band due to the combined effect of low gain and high loss at the band edge
Solution Approach 1:
The spatial arrangement parameter of input waveguides is changed to invert their positions relative to wavelength order. This parameter change compensates for the wavelength-dependent loss parameter of the AWG, thereby improving the minimum optical power across the entire wavelength band and enabling higher overall power output.
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 configuration reduces the wavelength dependence of the optical power, allowing for higher optical power output and improved efficiency across the entire wavelength band, while also potentially reducing power consumption.
Implementation Method 1
The arrayed waveguide grating is configured to combine laser light beams from the semiconductor laser devices belonging to the first group into the same point by diffraction in a first diffraction order in the arrayed waveguide grating, and combine laser light beams from the semiconductor laser devices belonging to the second group into the same point by diffraction in a second diffraction order different from the first diffraction order
Data Source
AI summary
An optical semiconductor apparatus includes: semiconductor laser devices having different emission wavelengths and grouped into at least a first group and a second group; and an arrayed waveguide grating connected to the semiconductor laser devices of the first and second groups and configured to combine laser light beams radiating from the semiconductor laser devices into a same point. The arrayed waveguide grating is configured to combine laser light beams from the semiconductor laser devices belonging to the first group into the same point by diffraction in a first diffraction order in the arrayed waveguide grating, and combine laser light beams from the semiconductor laser devices belonging to the second group into the same point by diffraction in a second diffraction order different from the first diffraction order, in the arrayed waveguide grating.