44 research outputs found
High Power, Continuous-wave Supercontinuum Generation in Highly Nonlinear Fibers Pumped with High Order, Cascaded Raman Fiber Amplifiers
A novel method for efficient generation of high power, equalized
continuous-wave supercontinuum source in an all conventional silica fiber
architecture is demonstrated. Highly nonlinear fiber (HNLF) is pumped in its
anomalous dispersion region using a novel, high power, L-band laser. The L-band
laser encompasses a 6th order cascaded Raman amplifier which is pumped with a
high power Ytterbium doped fiber laser and amplifies a low-power, tunable
L-band seed source. The supercontinuum generated 35W of power with ~40%
efficiency. The Supercontinuum spectrum was measured to have a high degree of
flatness of better than 5 dB over 400 nm of bandwidth (1.3 - 1.7 micron,
limited by spectrum analyzer range) and a power spectral density in this region
of >50 mW/nm. The extent of the SC spectrum is estimated to be upto 2 micronComment: 6 pages, 5 figure
Generation of tunable, high repetition rate optical frequency combs using on-chip silicon modulators
We experimentally demonstrate tunable, highly-stable frequency combs with
high repetition-rates using a single, charge injection based silicon PN
modulator. In this work, we demonstrate combs in the C-band with over 8 lines
in a 20-dB bandwidth. We demonstrate continuous tuning of the center frequency
in the C-band and tuning of the repetition-rate from 7.5GHz to 12.5GHz. We also
demonstrate through simulations the potential for bandwidth scaling using an
optimized silicon PIN modulator. We find that, the time varying free carrier
absorption due to carrier injection, an undesirable effect in data modulators,
assists here in enhancing flatness in the generated combs.Comment: 10 pages, 7 figure
Fast Characterization of Dispersion and Dispersion Slope of Optical Fiber Links using Spectral Interferometry with Frequency Combs
We demonstrate fast characterization (~1.4 microseconds) of both the
dispersion and dispersion slope of long optical fiber links (~25 km) using dual
quadrature spectral interferometry with an optical frequency comb. Compared to
previous spectral interferometry experiments limited to fiber lengths of
meters, the long coherence length and the periodic delay properties of
frequency combs, coupled with fast data acquisition, enable spectral
interferometric characterization of fibers longer by several orders of
magnitude. We expect that our method will be useful to recently proposed
lightwave techniques like coherent WDM and to coherent modulation formats by
providing a real time monitoring capability for the link dispersion. Another
area of application would be in stabilization of systems which perform
frequency and timing distribution over long fiber links using stabilized
optical frequency combs.Comment: 3 pages, 3 figures, Minor changes to tex
Single Shot Amplitude and Phase Characterization of Optical Arbitrary Waveforms
Using a time-gated dual quadrature spectral interferometry technique, for the
first time we demonstrate single-shot characterization of both spectral
amplitude and phase of ~1THz bandwidth optical arbitrary waveforms generated
from a 10 GHz frequency comb. Our measurements provide a temporal resolution of
1ps over a record length of 100ps. Singleshot characterization becomes
particularly relevant when waveform synthesis operations are updated at the
repetition rate of the comb allowing creation of potentially infinite record
length waveforms. We first demonstrate unambiguous single shot retrieval using
rapidly updating waveforms. We then perform additional single-shot measurements
of static user-defined waveforms generated via line-by-line pulse shaping.Comment: 10 pages, 6 figures. Added new references and minor changes to tex
High Power, Tunable, Continuous-Wave Fiber Lasers in the L-band using Cascaded Raman Amplifiers
We demonstrate a high power, all-fiber, tunable laser source that can operate
in the L-band region. A low power, tunable input laser is amplified with a
recently proposed, high efficiency, 6th order cascaded Raman amplifier. The
proposed system is scalable and overcomes the limitations of Erbium and
Erbium-Ytterbium co-doped fiber lasers for power scaling. A tunable
Erbium-Ytterbium co-doped fiber ring laser generating ~0.5W of power and
tunable in the 1560-1590 nm wavelength range is utilized as the seed source.
The output from the seed laser is amplified to ~24 W using 6th order cascaded
Raman amplification. A high power Yb laser operating at 1117nm is used as the
pump laser for driving the Raman conversions. The operating wavelength of the
demonstrated laser in the eye-safe, atmospherically transparent region enables
high power free-space applications. In addition, this source enables other
interesting applications such as high power supercontinuum generation with
conventional silica fibers.Comment: 6 pages, 5 figure