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ABSTRACT: A hybrid mode-locked Erbium-doped fiber laser that provides very short pulse-widths while achieving high repetition rates is proposed and experimentally demonstrated. This hybrid configuration is realized by using a thin film of polydimethylsiloxane (PDMS) doped with single wall carbon nanotubes (SWCNT). This PDMS/SWCNT composite acts as a saturable absorber and is inserted within an active mode-locked laser system using angled connectors. Therefore, the effect of the PDMS/SWCNT composite is to effectively narrow the width of the pulses generated by the active system without modifying its repetition rate. A pulse-width of 730 fs was generated at a repetition rate of 4 GHz, while achieving an average output power of 4 mW. A reduction in the noise of the photodetected RF spectrum was also observed in the hybrid system.
Journal of Lightwave Technology 12/2011; · 2.78 Impact Factor
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ABSTRACT: We report Carrier Envelope Offset (CEO) frequency measurements of a 10 GHz harmonically mode-locked, Fabry-Perot etalon-stabilized, semiconductor optical frequency comb source. A modified multi-heterodyne mixing technique with a reference frequency comb was utilized for the measurement. Also, preliminary results from an attempt at f-2f self-referencing measurement are presented. The CEO frequency was found to be ~1.47 GHz for the particular etalon that was used.
Optics Express 08/2011; 19(18):16851-65. · 3.59 Impact Factor
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ABSTRACT: A novel method of measuring the optical frequency stability of a continuous-wave (CW) laser by using an etalon-based optoelectronic oscillator is demonstrated. A 1000 finesse Fabry-Pérot etalon is used as a reference which eliminates the need of using an independent optical source as a frequency reference. Using this technique, the optical frequency stability of a CW laser is measured with ~3.5-kHz optical frequency resolution at update rates of 90 Hz.
IEEE Photonics Technology Letters 03/2011; · 2.19 Impact Factor
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ABSTRACT: We present a semiconductor-based laser cavity operating in the extreme chirped pulse amplification regime using a 100 MHz fiberized Fabry-Perot etalon. An intra-cavity modified Hänsch-Couillaud scheme ensures long-term operation. The laser exhibits supermode noise spur suppression and a semiconductor-based optical frequency comb is generated.
IEEE Photonics Society, 2010 23rd Annual Meeting of the; 12/2010
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ABSTRACT: Detection of phase-modulated optical signals without the use of an externally generated local oscillator is demonstrated using an injection-locked vertical-cavity surface-emitting laser. When it is used in a multichannel system, this technique is also capable of actively filtering out one of the phase-modulated optical carriers. The experimental results of the proposed receiver performance in a three-channel optical system are presented here. A signal-to-noise ratio of 75 dBc/Hz is obtained.
IEEE Photonics Technology Letters 11/2010; · 2.19 Impact Factor
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ABSTRACT: We introduce a novel scheme for dynamic line-by-line pulse shaping with GHz update rates. Four lines of an optical frequency comb source are used to injection-lock four individual VCSEL, which are subsequently electrically modulated at 0.4 to 1 GHz through current modulation. This concept could be considered a completely new way of pulse shaping as the light is not simply modified, but rather regenerated with the desired properties. We also discuss an important drawback of line-by-line pulse shapers that ultimately limits the modulation speed capability.
Optics Express 08/2010; 18(17):18284-91. · 3.59 Impact Factor
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ABSTRACT: In this work, we demonstrate mode partition noise in the radio-frequency spectra of periodic signals generated using electrical pattern generators that are often used in digital optical communications and error testing. This effect makes the measurement of the amplitude modulation noise of the repetitive signal through its single sideband (SSB) power spectral density (PSD) at its fundamental frequency inaccurate. This is demonstrated for a square wave, where the dependence of the SSB PSD on the duty cycle of the signal is experimentally shown. To alleviate this ambiguity, we propose and experimentally demonstrate a photonic up-convert and down-convert method that results in invariant SSB power spectra at the signal's fundamental frequency.
IEEE Photonics Technology Letters 07/2010; · 2.19 Impact Factor
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ABSTRACT: An optical frequency stability measurement setup based on a Fabry-Perot Etalon reference is presented that results in measurements with ~1.4 kHz optical frequency resolution at update rates of 90 Hz.
Lasers and Electro-Optics (CLEO) and Quantum Electronics and Laser Science Conference (QELS), 2010 Conference on; 06/2010
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ABSTRACT: Group delay and higher order dispersion measurements are conducted on a 1.3 μm quantum dot semiconductor optical amplifier at various injection currents. White-light spectral interferometry is performed, along with a wavelet transform to recover the group delay. The group delay, group velocity dispersion, and higher order dispersion terms are quantified. The measurement spans both ground state and first excited state transitions, ranging from 1200 to 1320 nm. The group velocity dispersion, β2, is found to be −6.3×103 fs2 (7.6 fs/nm) at an injection current of 500 mA.
Applied Physics Letters 05/2010; 96(21):211907-211907-3. · 3.84 Impact Factor
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ABSTRACT: In this work, a 10.287-GHz semiconductor-based harmonically mode-locked laser with 1000 finesse intracavity etalon is demonstrated. The timing jitter integrated from 1 Hz to 100 MHz (Nyquist) is 3 fs (14 fs). The optical linewidth is ~500 Hz and the optical frequency stability is <150 kHz over 30 s.
IEEE Photonics Technology Letters 04/2010; · 2.19 Impact Factor
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ABSTRACT: A resonant cavity interferometric intensity modulator with pure linear response is proposed and the first experimental demonstration is presented. This modulator has multi-gigahertz bandwidth and potentially infinite spurious free dynamic range.
LEOS Annual Meeting Conference Proceedings, 2009. LEOS '09. IEEE; 11/2009
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ABSTRACT: An optical frequency stabilized, coupled optoelectronic oscillator(COEO) with 1000 finesse intracavity etalon is presented with 10.287 GHz optical comb separation, <1kHz optical linewidth and >121dBc/Hz RF supermode noise spur suppression.
LEOS Annual Meeting Conference Proceedings, 2009. LEOS '09. IEEE; 11/2009
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ABSTRACT: In this letter, a feedforward system is developed for control of a quasi-continuous-wave (CW) chirped source. The goal of this study is to improve the uniformity of the temporal profile of a quasi-CW chirped laser source. The chirped spectrum input to the system is dynamically flattened using a feedforward scheme having bandwidth in excess of 1 GHz, resulting in more than three times reduction on the contrast of the input spectrum. A uniform chirped spectrum laser source can be used in time-stretched photonic analog-to-digital conversion, as part of laser radar system, or for optical coherence tomography.
IEEE Photonics Technology Letters 10/2009; · 2.19 Impact Factor
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ABSTRACT: We report the generation of optical pulse trains with 380 as of residual timing jitter (1 Hz-1 MHz) from a mode-locked external-cavity semiconductor laser, through a combination of optimizing the intracavity dispersion and utilizing a high-power, low-noise InGaAsP quantum-well slab-coupled optical waveguide amplifier gain medium. This is, to our knowledge, the lowest residual timing jitter reported to date from an actively mode-locked laser.
Optics Letters 03/2009; 34(3):238-40. · 3.40 Impact Factor
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ABSTRACT: A novel method is presented to provide long-term stabilization of an injection-locked harmonically mode-locked laser to a narrow linewidth continuous-wave (CW) source for the first time. The method, based on the Pound-Drever-Hall method of laser frequency stabilization, exploits the phase shift across a laser cavity mode resonance to detect the offset between the CW frequency and the combline frequency desired for injection-locking. Long-term suppression of the radio-frequency supermode noise spurs is shown as well as 36-dB suppression of optical supermodes. Significant reductions in phase and amplitude noise are also shown due to injection. Postamplification noise results are presented, showing an increase in optical power per combline with no degradation in pulse-to-pulse energy fluctuation or timing jitter.
IEEE Photonics Technology Letters 02/2009; · 2.19 Impact Factor
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ABSTRACT: In this letter, we introduce a novel interferometric method for dynamic extinction ratio measurement of temporally demultiplexed pulses. A high extinction intensity modulator is used in order to temporally demultiplex the pulse train. The resulting extinction ratio is measured to be 44 dB. Our method has a dynamic range of ~60 dB. To our knowledge, this is the highest dynamic extinction ratio measurement method reported to date for high-speed optical modulators.
IEEE Photonics Technology Letters 01/2009; · 2.19 Impact Factor
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ABSTRACT: A coupled optoelectronic oscillator (COEO) based on a laser with a high finesse intracavity etalon is presented. Unlike a conventional COEO, the incorporation of the etalon produces a 10.24-GHz spaced optical frequency comb by selecting a single optical supermode. The same etalon serves as a reference for active stabilization of the optical frequencies and the pulse repetition rate via the Pound-Drever-Hall stabilization method. This results in 160 to 190 comb lines with sub-1-MHz drift and sub-10-kHz linewidth, as well as subpicosecond pulses and 350-Hz maximum deviation of the pulse repetition rate over 10 min. The completely self-contained source allows the COEO utility to extend to a host of new coherent communication and signal processing applications.
Journal of Lightwave Technology 09/2008; · 2.78 Impact Factor
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ABSTRACT: We introduce a novel interferometric method for dynamic extinction ratio measurement of temporally demultiplexed pulses by using a high extinction modulator. The resulting extinction ratio is 44 dB. Our method has a dynamic range of ~60 dB.
Lasers and Electro-Optics, 2008 and 2008 Conference on Quantum Electronics and Laser Science. CLEO/QELS 2008. Conference on; 06/2008
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ABSTRACT: The general features and characteristics of two different external-cavity mode-locked semiconductor lasers (MSLs) were studied. Coherent optical frequency combs and short pulses from the MSLs were used to develop a synchronized MSL system. Exploiting the synchronized MSLs as a phase-locked transmitter and a local oscillator, various heterodyne and homodyne coherent detection techniques were experimentally demonstrated. The experimental results have shown that the phase-coherent optical frequency combs and short pulses from the synchronized MSLs are very promising optical sources for many future coherent photonic systems, especially for spectrally phase-encoded optical code-division multiple access (SPE-OCDMA).
Journal of Lightwave Technology 05/2008; 26(8):908-921. · 2.78 Impact Factor
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ABSTRACT: Improvement of two orders of magnitude of the Pound-Drever-Hall based free spectral range (FSR) measurement method is reported. The improved technique results in 1 part in 10<sup>6</sup> precision. This is believed to be the most precise measurement of FSR.
Electronics Letters 02/2008; · 0.96 Impact Factor
