P.J. Delfyett

University of Central Florida, Orlando, Florida, United States

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Publications (208)205.12 Total impact

  • The European Conference on Lasers and Electro-Optics; 05/2013
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    ABSTRACT: An algorithm for self-referenced spectral magnitude and phase retrieval of both optical frequency combs from a dual-comb multiheterodyne interferogram is rigorously defined. The algorithm is generalized to allow for the repetition rates of the two combs to be significantly different which allows for a reduction in required RF bandwidth. The validity of the algorithm is confirmed with an experimental demonstration.
    Journal of Lightwave Technology 01/2013; 31(23):3758-3764. · 2.56 Impact Factor
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    ABSTRACT: A spectrally efficient multiheterodyne scheme is applied for the independent measurement of the spectral phase profiles of three distinct semiconductor frequency combs. The amount of quadratic and cubic phase is quantified for each source, providing insight on the dispersive properties of the semiconductor gain and the fiberized laser cavity. This information is vital for the optimization and expansion of the spectral bandwidth of such sources.
    IEEE Journal of Selected Topics in Quantum Electronics 01/2013; 19(4):1100711-1100711. · 4.08 Impact Factor
  • A. Ardey, E. Sarailou, P.J. Delfyett
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    ABSTRACT: We investigate and confirm a four-wave mixing (FWM) process as the primary mechanism responsible for locking and stabilization of a previously reported novel quantum dot based monolithically coupled colliding pulse mode-locked (CPM) laser. In the previous letter, a high-Q passively mode-locked ring laser is used to injection lock an orthogonally coupled passively mode-locked CPM slave laser via FWM in the common saturable absorber. In this letter, we setup an experiment to verify the FWM process, whereby the external ring laser is operated unidirectionally while simultaneously analyzing the amplified spontaneous emission from the other facet of the ring laser. The emission is found to contain CPM light only in the presence of injection locking proving the FWM process. Other linear scattering effects are also investigated and shown to be negligible in the orthogonal waveguide configuration.
    IEEE Photonics Technology Letters 01/2013; 25(16):1566-1569. · 2.04 Impact Factor
  • S.P. Bhooplapur, P.J. Delfyett
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    ABSTRACT: Experimental measurements of the optical amplitude and phase modulation from an injection-locked VCSEL at 1550 nm are reported. The use of a coherent optical demodulation technique, using a 90° optical hybrid, balanced photodiodes, and a high-speed oscilloscope, has enabled the complete modulation response to be recorded as a function of time. The VCSEL's response to current modulation was examined under various experimental parameters: over a wide frequency range, from kilohertz to gigahertz, for small and large current modulation and for different bias currents. Low-frequency (<;1 MHz) current modulation leads to temperature modulation, where the injection-locked VCSEL acts predominantly as a phase modulator, with a maximum depth of phase modulation, β, of 0.34 π rad. In the high-frequency (>100 MHz) electronic modulation regime, the VCSEL produces significant amplitude and phase modulation, with a maximum depth of amplitude modulation, m, of 35% and β = 0.47 π rad. The VCSEL's thermal response is much more efficient (requires less RF power) in producing phase modulation than its electronic response. The detailed experimental data on the optical phase modulation response of an injection-locked VCSEL are reported for the first time here and are useful for its many applications.
    IEEE Journal of Selected Topics in Quantum Electronics 01/2013; 19(6):6-13. · 4.08 Impact Factor
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    ABSTRACT: Waveguide coupling to closed loop coupled-resonator optical waveguides is explored. By coupling a CROW chain back on itself, a reduction in individual resonant linewidth is achieved making these slow light modes more conducive to periodic filters toward novel frequency-comb integration. Through numerical simulation by finite-difference time-domain methods, the importance of waveguide symmetry conditions for coupling is illustrated. The impact of unit cavity mode symmetry strongly impacts the necessary coupling geometry to both cavities and waveguides. Design insight into different waveguide coupling schemes is provided while aiming to achieve transmission of the resonant structure exhibited by the isolated resonator.
    Journal of Lightwave Technology 01/2013; 31(9):1426-1432. · 2.56 Impact Factor
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    ABSTRACT: A monolithic AlInGaAs quantum well Fabry-Pérot laser injection locked to a passively mode-locked monolithic laser is presented here. The FP laser cavity can be used as a true linear interferometric intensity modulator for pulsed light.
    05/2012;
  • S.P. Bhooplapur, N. Hoghooghi, P.J. Delfyett
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    ABSTRACT: Using a coherent optical demodulation technique, we have independently measured the AM and PM resulting from current modulation at GHz rates of an I.L. VCSEL at 1.55 μm. The variation of the depth of AM and PM are measured as function of RF modulation frequency and power. Two regimes of modulation for the I.L. VCSEL are explored: 1) At low frequencies ; 100 MHz where carrier concentration modulation dominates and both AM and PM are significant. This data is vital for the use of VCSELs as modulators in communications systems.
    Photonics Conference (IPC), 2012 IEEE; 01/2012
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    ABSTRACT: In this paper, we show recent results in the use of stabilized optical frequency combs from mode-locked diode lasers operating in the telecommunication C-band for applications in coherent parallel signal processing architectures. For selecting and modulating single components within the frequency comb, novel approaches that rely on the properties of injection locked oscillators will be used. These approaches will show that one can simultaneously select single components from a frequency comb and realize either modulation or detection functionality. To demonstrate how stabilized frequency combs can be used in a coherent signal processing scenario, we use the frequency combs and injection locked microcavity lasers to perform real time waveform generation, measurement, and matched filtering.
    Avionics, Fiber- Optics and Photonics Technology Conference (AVFOP), 2012 IEEE; 01/2012
  • M.U. Piracha, D. Nguyen, P.J. Delfyett
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    ABSTRACT: Lidar systems are important for performing many different tasks such as remote sensing, altimetry and imaging. Chirped pulsed lidar systems employing chirped fiber Bragg gratings (CFBGs) for long distance, high resolution ranging and velocimetry have been demonstrated. Broadband CFBGs with dispersions of up to 2 ns/nm across the C-band have recently become commercially available. However, due to imperfections and noise in the grating fabrication process, larger dispersion values come at the price of larger ripple in the group delay. In this paper, we demonstrate a technique that utilizes spectral phase modulation to remove the group delay ripple (GDR) of a CFBG while maintaining a dispersion of 1651 ps/nm across the C-band. The GDR removal is experimentally verified by utilizing the linearly chirped, GDR-free optical pulse train in a chirped pulse lidar setup where a two-fold improvement in the lidar range resolution is observed. In the future, this approach may be used to achieve range resolution of a few hundred micrometers over target distances greater than 10 km, and also for doubling the resolution of chirped pulse Doppler velocity measurements.
    Avionics, Fiber- Optics and Photonics Technology Conference (AVFOP), 2012 IEEE; 01/2012
  • M.U. Piracha, D. Nguyen, P.J. Delfyett
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    ABSTRACT: Spectral phase modulation is used to compensate for the group delay ripple ( +/- 50 ps) of a chirped fiber Bragg grating (dispersion = 1651 ps/nm) to achieve a range resolution of 320 μm in a chirped pulse laser radar. Simulation results are also presented, confirming the improvement in laser radar performance due to compensation of the group delay ripple.
    Photonics Conference (IPC), 2012 IEEE; 01/2012
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    ABSTRACT: A first demonstration of fiber based CPA system with an active feedback loop utilizing spectral phase and intensity modulation to generate clean, high contrast, 10 dB pedestals suppression, transform limited pulse with parabolic intensity profile.
    Lasers and Electro-Optics (CLEO), 2012 Conference on; 01/2012
  • D. Nguyen, M.U. Piracha, P.J. Delfyett
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    ABSTRACT: Fiber chirped pulse amplification (CPA) systems have many advantages such as size compactness and significant simplification of complex optical components over bulk solid state amplifiers. Moreover, precise optical alignment in free space is not required. However, fiber CPA systems are also much more vulnerable to nonlinear effects due to their small mode areas and long interaction length, resulting in pulse distortion, and consequently, degradation of pulse quality. Pulse with parabolic intensity profile appears to be a very good candidate to mitigate such degradation effects and wave-breaking. Furthermore, its linear chirp allows efficient pulse compression to achieve high peak power, making it highly attractive to CPA systems. CPA systems with parabolic pulses therefore can have widespread use in applications such as super-continuum generation, optic fiber communications, thermal ablation, and ultrafast all-optical signal processing.
    Avionics, Fiber- Optics and Photonics Technology Conference (AVFOP), 2012 IEEE; 01/2012
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    ABSTRACT: A tunable optoelectronic oscillator using a high finesse etalon as both a photonic filter and optical frequency reference is presented. The microwave tone at 10.487 GHz displays fractional frequency instability of 3.3×10-10 at 1 s.
    Photonics Conference (IPC), 2012 IEEE; 01/2012
  • E. Sarailou, A. Ardey, N. Hoghooghi, P.J. Delfyett
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    ABSTRACT: A high speed intensity modulator with a linear transfer function is one of the key components in signal processing, optical communication and in high performance photonic analog to digital converters (ADC) for advanced Radar systems. Typically two types of modulators are available: electro-absorption and electro-optic modulators. The former has a linear response and large bandwidth but they are sensitive to temperature and wavelength changes and they cannot handle high optical power. The latter provides high speed modulation, high optical power handling and good bias stability but exhibits weak voltage sensitivity and a nonlinear transfer function which limits the spur free dynamic range [1].
    Avionics, Fiber- Optics and Photonics Technology Conference (AVFOP), 2012 IEEE; 01/2012
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    ABSTRACT: A tunable optoelectronic oscillator with a Fabry-Perot etalon acting as both an optical frequency reference and photonic filter has been demonstrated. The RF oscillation frequency may be changed by tuning of a VOD to harmonics of the etalon FSR. The generated microwave tone shows long term stability of 3.3×10-10 at 1 s.
    Avionics, Fiber- Optics and Photonics Technology Conference (AVFOP), 2012 IEEE; 01/2012
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    ABSTRACT: A comparative study of the performance of 10 GHz, semiconductor-based comb sources is presented with regard to the optical linewidth, stability of the comb modes, total optical bandwidth and timing jitter.
    Photonics Conference (IPC), 2012 IEEE; 01/2012
  • Dat Nguyen, M.U. Piracha, P.J. Delfyett
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    ABSTRACT: Sub-picosecond, transform-limited pulses with parabolic optical intensity profile were generated for fiber based chirped pulse amplification (CPA) systems. By utilizing parabolic pulse shaping with both spectral intensity and phase modulation, pulse peak power was increased by a factor of 5 when using chirped fiber Bragg gratings (CFBG) stretcher, and by a factor of 6.2 with a fiber spool stretcher. This is a very robust and versatile technique, easy to integrate into a wide range of CPA systems and applications.
    Photonics Conference (IPC), 2012 IEEE; 01/2012
  • S.P. Bhooplapur, N. Hoghooghi, P.J. Delfyett
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    ABSTRACT: This paper uses a coherent optical demodulation technique to measure the complete electric field in real-time from a modulated I.L. VCSEL. Modulation dynamics can be studied at GHz rates, including non-linear phenomena like the theoretically predicted arcsine shape of the PM. Based on balanced photodiodes and oscilloscopes available today, the technique can be applied to measure modulations beyond 25 GHz.
    Avionics, Fiber- Optics and Photonics Technology Conference (AVFOP), 2012 IEEE; 01/2012
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    ABSTRACT: In this paper, we show recent results in the use of injection locked vertical cavity semiconductor lasers (VCSELs) as novel modulators and narrowband optical filters that can be exploited for applications relevant to microwave photonics. Specifically, we exploit the phase modulation that is imparted onto the injection locked signal by modulating the current to the VCSEL. Optical filtering is realized by noting that there exists a 'locking range' which determines the amount of optical detuning from the free running VCSEL and the injection seed signal allowed for the injection locked process to work. Using these two salient properties of injection locked VCSELs, we show that one can simultaneously select single components from a frequency comb and realize either modulation or detection functionality. Furthermore, we show how injection locked VCSELs can be used in highly linear RF analog links and how VCSELs can be used with an optical comb to perform real time waveform generation.
    Photonics Conference (IPC), 2012 IEEE; 01/2012

Publication Stats

1k Citations
205.12 Total Impact Points

Institutions

  • 1994–2012
    • University of Central Florida
      • • Center for Research and Education in Optics and Lasers
      • • College of Optics & Photonics
      • • Florida Photonics Center of Excellence
      • • Department of Physics
      Orlando, Florida, United States
    • University of California, Davis
      • Department of Electrical and Computer Engineering
      Davis, CA, United States
    • City College of New York
      • Institute for Ultrafast Spectroscopy and Lasers
      New York City, New York, United States
  • 2007
    • Alcatel Lucent
      Lutetia Parisorum, Île-de-France, France
  • 2006
    • Telcordia Technologies
      Middlesex, New Jersey, United States
  • 1993–1994
    • Imperial College London
      • Department of Physics
      London, ENG, United Kingdom