Nano-Photonics Group



 

 

Nonlinear Optical Materials and Semiconductor Nanostructures

We carry out basic research on the nonlinear optical properties of fullerenes, semiconductor quantum wells, and semiconductor n-i-p-i structures.  Applications are in optical limiting, laser modelocking and Q-switching, and all-optical switching.

Optical Limiting with the Higher Fullerenes

 

 

Text Box: Optical limiters can be used to protect eyes or sensors from high intensity or high fluence light.  Carbon 60 is an optical limiter because it has reverse saturable absorption - an absorption that increases with optical excitation.  We investigate optical limiting with higher fullerenes and other nonlinear optical materials.

 

 

 

 


Journal Publications:

“Optical Limiting with Higher Fullerenes,” Alan R. Kost, John E. Jensen, R. O. Loufty and J. C. Withers,  Appl. Phys. B: Lasers and Optics 80, pp. 281-283 (2005).

Nonlinear Mirrors                                                                                                           

Text Box: Semiconductor quantum wells are saturable absorbers at high optical intensity.  The diagram shows how this effect was used in a nonlinear mirror that was used to modelock an  erbium-doped fiber laser and produce pseudo-random optical pulses for laser radar.

Journal Publications:

“Fabrication of Optically Nonlinear Semiconductor Mirrors for Modelocking of Neodymium-Doped Fiber Lasers,” Alan R. Kost, Monica L. Minden, and Hans W. Bruesselbach, IEEE J. Quantum Electron. 40 (8), pp. 1105-1112 (2004).

“A Range-Resolved Doppler Imaging Sensor Based on Fiber Lasers,” Monica L. Minden, Alan Kost, Hans W. Bruesselbach, Stanislav Ionov, Joseph Paranto, Dean Liskow, and Larry Humm, IEEE J. Select. Topics Quantum Electron. 3, pp. 1080-1086 (1997).
 

Hetero n-i-p-i Structures

Text Box: Hetero n-i-p-i materials exhibit very large carrier transport-type optical nonlinearity (Da ~ 3000 cm/W, Dn ~ 0.1 cm2/W) for all-optical switching at very low power.  The material can be fabricated into two-dimensional arrays of switching elements. Journal Publications: “Nonlinear Optical Properties of a Hetero-nipi Structure with Coupled Quantum Wells,” Alan R. Kost, Ron R. Carter, Elsa M. Garmire, and Thomas C. Hasenberg, Journal of Nonlinear Optical Physics and Materials 14 (3), pp. 1-12 (2005)  “Wavelength Dependence of Combined Local and Carrier Transport Optical Nonlinearities in a Hetero n-i-p-i Structure,” Alan R. Kost, Michael H. Jupina, Thomas C. Hasenberg, and Elsa M. Garmire, submitted to Journal of Applied Physics.    

Nonlinear Optical Techniques for Ultrafast Measurements

Our group also investigates nonlinear optical approaches for time-resolving ultrafast processes in semiconductors. We have recently shown that excitation correlation can be used to measure recombination coefficients for mid-infrared emitting semiconductors.  Unlike more conventional techniques, excitation correlation requires only slow photodetectors and optical excitation with a commercially available Ti:Sapphire laser.  The nano-photonics group is also investigating the use of four-wave mixing to measure spin relaxation rates in semiconductor optical amplifiers.

.

 

 

 

 

 

 

 

 

 

Text Box: GaInSb/InAs "Type-II" superlattices that emit in the mid-infrared.  These materials have been used for semiconductor lasers in the 3 - 5 micron range.

 

 

 

 

 

Journal Publication:

 “Time-Resolved Photocarrier Decay for Mid-Infrared Semiconductors with Excitation Correlation,” Alan R. Kost, Ulrich Pfeiffer, and Gottfried Döhler, Superlattices and Microstructures 37, pp. 373-379 (2005).

Text Box: A correlated photoluminescence signal is used to extract Shockley-Read-Hall, Radiative, and Auger coefficients for mid-infrared emitting semiconductors. The value of the Auger coefficient is particularly  important for evaluating the potential for the material use as the active layer in a semiconductorlaser.