Marcus Bagnell

Millimeter-Wave Generation in an Optoelectronic Oscillator Using an Ultrahigh Finesse Etalon as a Photonic Filter

A Fabry-Perot etalon with a finesse of 100 000 is used as a photonic filter in a single loop optoelectronic oscillator. The etalon provides narrow bandwidth microwave filtering at harmonics of its 1.5 GHz free spectral range for oscillation in the range of 6 to 60 GHz. Fiber delays as long as 2 km are added to the loop with no spurious modes visible above the noise floor. The environmental stability of the etalon makes it suitable as a secondary reference for feedback to the optical frequency which contributes to the reduction of phase noise and long term frequency drift.

Multiheterodyne Detection for Spectral Compression and Downconversion of Arbitrary Periodic Optical Signals

Optical frequency combs are used as local oscillators for the measurement and analysis of unknown optical waveforms with periodic time domain structures. Experimental results obtained by heterodyning pulsed and phase-modulated laser sources are presented. The analysis is then extended to the heterodyning and sampling of bandlimited incoherent light sources. It is shown theoretically and experimentally that the correlations between photodetected white light at different times can generate RF interference that is sensitive to the optical phase.

Free spectral range measurement of a fiberized Fabry–Perot etalon with sub-Hz accuracy

In this work a narrow linewidth (1 kHz) laser source is used to measure the free spectral range of a fiberized Fabry-Perot etalon with sub-Hz accuracy (10(-8)). A previously demonstrated technique based on the Pound-Drever-Hall error signal is improved in accuracy by the use of a narrow linewidth laser swept in frequency via an acousto-optic modulator, or single sideband generation. The sub-Hz (10(-8)) accuracy attained enables the characterization of both the long-term drift and the polarization dependence of the free spectral range of the fiberized etalon.

Ultralow Noise, Etalon Stabilized, 10-GHz Optical Frequency Comb Based on an SCOW Amplifier

A slab-coupled optical waveguide amplifier (SCOWA) is used to construct a 10-GHz harmonically modelocked laser with an intra-cavity etalon that serves as a high-finesse spectral filter. The laser output is a frequency comb that is actively stabilized to the transmission peaks of the etalon through a Pound-Drever-Hall scheme. The linewidth of the individual comb-lines is ~1 kHz and the frequency instability <;300 kHz over 60 s. The output power exceeds 20 mW due to the high saturation power of the SCOWA. The residual timing jitter of the pulse-train is ~1.9 fs (1 Hz to 100 MHz). A much broader comb (~10 nm) is generated after dispersion compensation of the cavity and the output pulses are compressible to <;1 ps. A comparison of the timing jitter of the all-anomalous dispersion and dispersion compensated cavities is presented along with a previous result with a similar architecture.

Dispersion measurements of a 1.3 μm quantum dot semiconductor optical amplifier over 120 nm of spectral bandwidth

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.

Highly stable optoelectronic oscillator with a 10 5 finesse etalon as a photonic filter

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.

Optoelectronic oscillator using an ultra-high finesse Fabry-Perot etalon as a photonic filter for low phase noise at high oscillating frequencies

A 100,000 finesse Fabry-Perot etalon with a 1.5 GHz free spectral range is used as a photonic filter in an optoelectorinc oscillator. The etalon acts as a ~15 kHz microwave filter to suppress spurious modes in a single loop OEO configuration. The etalon maintains its narrow filtering capability at harmonics of the FSR. Phase noise of the 10.5 GHz tone with 2 km of delay is measured at -120 dBc/Hz at 10 kHz offset. Oscillation as high as 54 GHz with 3 km of fiber delay is achieved while maintaining suppression of spurious modes below the noise floor of the measurement. Pound-Drever-Hall frequency stabilization of the laser frequency is used to reduce optical frequency noise and keep the laser frequency centered within the etalon resonance for long term operation of the OEO.

Multiheterodyne Detection and Sampling of Periodically Filtered White Light for Correlations at 20 km of Delay

A frequency comb is used as a set of coherent local oscillators to downconvert and spectrally compress white light that has been periodically filtered by a Fabry-Perot etalon. Multiheterodyne detection allows white light spread across 100 GHz of optical spectrum to be compressed to 5 GHz of radio frequency (RF) bandwidth for electronic sampling on an oscilloscope. Correlations are observed at delays of up to 20 km with a minimum resolution of less than 1 mm. Calculations show that resolution may be easily increased by increasing etalon finesse and frequency comb bandwidth.

Real-time Spectral Filtering and Interferometric Spectral Phase Compensation in a Feedback Fiberized High Power Chirped Pulse Amplification System

Parabolic spectral filtering and interferometric spectral phase compensation was implemented in a real-time feedback loop for high power fiber CPA system, resulting in near transform limited sub-picosecond pulses and 4.5 times increase in peak power

Multiheterodyne detection for self-referenced characterization of complex arbitrary waveforms from largely detuned optical frequency combs

Recently, it has been demonstrated that by considering a larger portion of the RF comb, a self-referenced measurement of each optical comb can be recovered, thus eliminating the need for a known reference with flat phase. In this manuscript, a more general form of this technique is explored, in which the mode spacings of the two unknown comb sources are detuned from each other by a factor of two or greater. This is a case of interest, seeing as how arbitrary waveforms generated from spectral modulation of OFCs which one might wish to characterize regularly exceed 10s of GHz rates, whereas the self-referenced, carrier-envelope offset stabilized sources which provide absolute knowledge of the optical frequencies involved in the multiheterodyne process are most commonly found in the sub-GHz repetition rate regime.