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Keywords: Optical, Laser

Market Overview

High-power semiconductor lasers that operate in the fundamental spatial mode are highly desired in a broad number of applications like optical communication, laser surgery, and more. An index-guided ridge waveguide (RW) structure is used to maintain single-mode operation in a transverse direction. Normally, these RW lasers will suppress or cut-off higher-order modes which leads to high power density operation and poor heat dissipation. More so, the maximum available output power from RW lasers is limited and the waveguide structures are susceptible to several degradations. There is a need in the market to introduce additional mechanisms in RW laser structures to avoid the onset of higher-order modes and simultaneously obtain high power. Clemson University researchers have developed a TRW laser structure that consists of a broad-ridge waveguide to provide dissipative modes that can couple with higher-order modes. This laser can effectively suppress all the undesired higher-order transverse modes under a threshold, ensuring single-mode operation with a larger emitting aperture and a higher output power than traditional RW lasers.


Laser Cutting & Welding, Laser Surgery, Spectroscopy, Integrated Optical Systems, Fiber Communication Systems

Technical Summary:

The proposed TRW structure achieves single-transverse mode lasing and high output power simultaneously through equipping the multimode active main waveguide with a pair of lossy auxiliary waveguides. The real parts of the propagation indices of the guided modes, supported by the auxiliary waveguides, are engineered to match with those of the higher-order modes supported by the main waveguide. By appropriately selecting the coupling coefficient (which can be controlled by adjusting the separation distance between the main and auxiliary waveguide or the etching depth) according to the gain-loss contrast between the main and the auxiliary waveguides, the higher order modes associated with the main waveguide will couple with the dissipative modes provided by the auxiliary waveguides and split into symmetric and anti-symmetric supermode pairs. Owing to the strong loss added in the auxiliary waveguides, the modal losses and accordingly lasing thresholds of the higher-order modes are significantly increased.


• Capable of single-mode operation without the expense of increasing the threshold current.
• Easier to couple the laser beam out with higher alignment tolerance.
• Does not require modification of the epitaxial structure and is therefore compatible with current epitaxial technique, making it capable of low cost and mass production.

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Technology Overview

State of Development


Patent Type




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CURF Reference No.



Lin Zhu, Xiaolei Zhao, Yeyu Zhu

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