Dissertation Defense by James Philip Hendrie on Tailored Frequency Comb Structures and Their Sensing Applications

Departmental News

James Philip Hendrie

Posted: August 11, 2019

Date: Monday, August 12th, 2019  

Time:  9:30 AM

Location:  CHTM, Room 103

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James Philip Hendrie


The focus of this doctoral dissertation is the development and investigation of nested cavity mode-locked lasers and their resultant tailored frequency combs.  A nested cavity is made up of two cavities, known as parents.  One parent is a larger, active, 100MHz Ti:Saph oscillator and the other is a smaller, passive, 7GHz Fabry-Perot Etalon (FPE).  Unlike standard frequency combs that are continuous, a tailored comb’s teeth are distributed in equally spaced groups where the center of each group corresponds to the resonance of the FPE and the side bands are determined by the resonances of the Ti:Saph.  This unique coupling of the MHz and GHz resonances opens the door to a wide variety of applications.     

One such application is the enhancement of Intracavity Phase Interferometry (IPI).  IPI is a technique in which two pulses propagate within a shared active oscillator.  These pulses experience a difference in phase, $\Delta\phi$, which results in a frequency comb shift of , where  is the round-trip time of the oscillator, relative to one another.   is measured as a beat-note signal when the two pulses are interfered and can be resolved at less than a kHz value with Hz resolution.  Nested cavities were introduced into this technique to further enhance the beat-note signal.  The enhancement comes from the fact that the frequency group locations in a tailored comb are set by the passive parent’s optical properties, which are frequency dependent. Therefore,  increases as the FPE’s linear dispersion further separates the two combs.  While this dissertation will focus on IPI as it relates to gyroscopes, it has also been demonstrated in magnetic field and  measurements.     

The successful demonstration of IPI enhancement, along with the characterization and stability of tailored combs, are presented and discussed.