TITLE:

Ultrafast Light Control: fiber amplifiers, quantum cascade lasers, and nano LEDs

DATE:

Friday, November 15th, 2013

TIME:

3:30 PM

LOCATION:

GMCS 214

SPEAKER:

Dr. Lyuba Kuznetsova. Physics Department at San Diego State University

ABSTRACT:

Laser and laser diode technology is at the heart of modern optics which is now, not just limited to imaging, but extends to communication, sensing, and even welding of automobile parts. Manipulation of light is essential to exploiting its potential, but light is difficult to control on length scales smaller than the wavelength and on time scales approaching tens-of-optical cycles.

This talk will cover a few concepts and materials systems that are promising for designing laser systems with light confined in time and space. In the first half of the talk, I will discuss challenges, techniques and approaches for short pulse generation and amplification in two laser systems: fiber amplifiers and quantum cascade lasers. The techniques and principles are similar for both laser systems but differences of emission wavelength and device size for each system present various challenges. First, I will talk about the major problem for fiber systems: nonlinearity and also about some newly discovered phenomena which have changed the paradigm for short pulse amplification in fiber amplifiers. I will next discuss results of the first unequivocal demonstration of mid-infrared mode-locked pulses from quantum cascade lasers.

In the second part of the talk I will present a study of microcavity light emitting diodes (LEDs) with dimensions approaching the wavelength of light which could perhaps answer one of the fundamental questions of photonics: Is it possible to make the rate of spontaneous emission comparable to the optical frequency itself? Study of strong and weak coupling between the microcavity optical mode and the silicon emitters in microdisks will be discussed. I will then describe the experimental results on increasing the internal efficiency via Purcell enhancement for electrically pumped microcavity InGaN/GaN LEDs with the smallest dimensions to date. Finally, I will talk about our recent study of the Al:ZnO/ZnO multilayer “superlattice” metamaterial with hyperbolic dispersion and conclude with the possible directions for future work toward creating “infinitely small” microcavity ultrafast LEDs and low threshold lasers.

HOST:

Dr. Jose Castillo

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