A New Antenna-feedback Scheme to Achieve Emission in a Narrow Beam from Metal-cavity Semiconductor Lasers



The invention is based on a distributed antenna-coupling (feedback) scheme and specially designed distributed feedback (DFB) metallic cavity grating. By ensuring the predesigned phase condition, the mode traveling inside the waveguide is coupled/phase-locked to the mode traveling outside on the top metal, hence establishing a standing-wave on top of the structure in addition to one existing inside the cavity. Due to the subwavelength vertical dimension in the cavity, a large amount of electric field couples to a surface-plasmon mode attached to the top metal cladding, where the electrical field is exponentially decaying in air. Single-mode emission in a narrow beam pattern, with an order of magnitude increase in output power is predicted, compared to previous DFB schemes. There are specially designed apertures in the metal-cladding, which act like individual components of a phased-array antenna transmitter.


Competitive Advantage


The improved performance characteristics, relatively simple design, ease of fabrication and/or integration represent key advantages and discriminators of this invention in comparison to the previously reported methods, such as Second-order DFB, Plasmonic Collimation, Photonic Crystals and Thirdorder DFB schemes. The technique is fully scalable to metal-clad semiconductor lasers operating in a wide range of electromagnetic spectrum, such as visible and infrared frequencies, as long as a sub-wavelength

confinement is preserved in the cavity. Moreover, the monolithically integrated phase-locked laser arrays can also benefit from the invention to increase the overall output power or plug-in efficiency.


Lehigh Tech ID # 062714-01


Market Need/Opportunity


THz metal-metal QCLs have potential applications in biological and medical sciences, security screening, illicit material detection, non-destructive evaluation, astrophysics and atmospheric science, manufacturing and process control, communications, and ultrafast spectroscopy. The terahertz market is expected to grow from $47 million in 2012 to $482 million in 2022, with a strong compound annual growth rate of 26 %, accordingly to THz technologies market analysis by Tematys, (Industrial Photonics, April 2014).

Industrial applications hold the biggest market share, representing around 50% of the total THz market with $21 million in 2012 and $241 million expected in 2022. There is a very strong interest in security spectrometry (approximately 80-95% of explosives, and all commonly used ones, have unique and identifiable THz signatures).




Lehigh University is looking for a partner for further development and commercialization of this technology through a license. The inventor is available to further discuss the technology under a NDA.



App Type Country Serial No. Patent No. File Date Issued Date Expire Date
Provisional [PR] United States 62/097,886 12/30/2014    
For Information, Contact:
Rick Smith
Lehigh University
Sushil Kumar
Chongzhao Wu