Tunable VCSEL with Segmented Dielectric Mirror
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Solution Overview
Problem
Dielectric DBR in wavelength tunable VCSELs has a reflectivity dip region, leading to increased oscillation threshold and limited tunable wavelength band due to interference effects, making it difficult to achieve wide wavelength tunability.
Innovation Solution
A surface emitting laser design with a second reflecting mirror featuring a single-crystal semiconductor beam and a dielectric multilayer film arranged in an opening, avoiding interference and maintaining high reflectivity across a wider wavelength band by positioning the beam and multilayer film to prevent weakening interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dielectric DBR is used as the second reflecting mirror, then high reflectivity in a wide wavelength band is achieved, but a reflectivity dip region occurs causing increased oscillation threshold and limited wavelength tunability
Solution Approach 1:
The second reflecting mirror is segmented into a beam portion and a dielectric multilayer film portion that are spatially separated. The dielectric multilayer film is arranged in an opening formed in the beam, creating distinct functional zones that prevent interference between the beam and the reflective layers, thereby eliminating the reflectivity dip while maintaining high reflectivity across a wide wavelength band.
2Length of moving object
If the dielectric multilayer film is positioned close to the active layer, then cavity length is reduced, but interference with the beam occurs causing oscillation instability
Solution Approach 1:
The dielectric multilayer film is extracted from the continuous beam structure and placed in a separate opening region. This spatial separation removes the source of interference between the beam and the reflective film, stabilizing oscillation while allowing the cavity length to be optimized for wavelength tuning.
3Ease of manufacture
If a conventional DBR structure is used, then manufacturing is simplified, but mode hop occurrences increase and wavelength sweeping becomes unstable
Solution Approach 1:
The reflecting mirror structure is segmented into separate beam and dielectric multilayer film components positioned in an opening. This segmentation prevents interference effects that cause mode hops, enabling stable wavelength sweeping while maintaining manufacturability through standard semiconductor fabrication processes.
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 widens the tunable wavelength band, stabilizes wavelength sweeping, and reduces mode hop occurrences, ensuring efficient oscillation across a broader spectral range.
Implementation Method 1
the reflectivity spectrum of the dielectric DBR has a region called dip in which the reflectivity is largely decreased as compared with other regions... oscillation threshold increases with the wavelength corresponding to the dip
Implementation Method 2
a surface emitting laser... an oscillation wavelength being tunable... the cavity length is varied by mechanically moving one (a movable mirror) of the pair of reflecting mirrors
Data Source
AI summary
A surface emitting laser having a wide wavelength tunable band is provided.A surface emitting laser includes a first reflecting mirror (102); a second reflecting mirror (116); and an active layer (104) arranged between the first reflecting mirror (102) and the second reflecting mirror (116), a gap being formed between the second reflecting mirror (116) and the active layer (104), an oscillation wavelength being tunable. The second reflecting mirror (116) includes a beam (108) comprising a single-crystal semiconductor, and a dielectric multilayer film (110) supported by the beam (108), and the dielectric multilayer film (110) is arranged in an opening (118) formed in the beam (108).