Approach to accurately measuring the speed of optical precursors

2011

Precursors can serve as a bound on the speed of information with dispersive medium. We propose a method to identify the speed of optical precursors using polarization-based interference in a solid-state device, which can bound the accuracy of the precursors' speed to less than $10^{-4}$ with conventional experimental conditions. Our proposal may have important implications for optical communications and fast information processing.

1998

A novel ultrafast optical signal measurement technique is proposed that uses a fast photodetector and electrooptic (EO) sampling. The technique can satisfy three requirements for the measurement: large bandwidth, high sensitivity, and polarization independence. The measurement systems are demonstrated using two kinds of EO sampling con®gurations. One system uses direct EO sampling. It affords a larger bandwidth. The system can discern 100-Gbit s A1 return-to-zero (RZ) optical pulse-pattern signals with an on±off ratio of 22 dB. The other system uses a waveguide intensity modulator in EO sampling. It affords higher sesitivity and can measure an 80-Gbit s A1 RZ optical eye diagram. It is theoretically expected that the sensitivity of our system is higher than that of the all-optical technique.

Applied Optics

A new modality for probing ultrafast phenomena that relies on radially or azimuthally polarized probe pulses is presented. First, we describe the principle and then theoretically analyze the signals expected for different types of pump-induced nonlinearities. Last, we experimentally verify the methodology by probing a pump-induced Kerr gate with a time-delayed radially polarized probe pulse. In general, we find excellent agreement between the simulated and measured results.

Optics Letters, 2010

The operation of a polarization-mode dispersion monitor insensitive to chromatic dispersion is demonstrated at 40 Gbits=s. The high-speed processing device is based on the Kerr effect and provides an optical power output as a reading of differential group delay. The monitor is compatible with return-to-zero modulation formats at data rates in excess of 40 Gbits=s and does not require the use of high-data-rate electronics.

Optics express, 2013

We demonstrate an optically controlled polarizer at ~1323 nm using a ladder transition in a Rb vapor cell. The lower leg of the 5S(1/2),F = 1->5P(1/2),F = 1,2->6S(1/2),F = 1,2 transitions is excited by a Ti:Sapphire laser locked to a saturated absorption signal, representing the control beam. A tunable fiber laser at ~1323 nm is used to excite the upper leg of the transitions, representing the signal beam. When the control beam is linearly polarized, it produces an excitation of the intermediate level with a particular orientation of the angular momentum. Under ideal conditions, this orientation is transparent to the signal beam if it has the same polarization as the control beam and is absorbed when it is polarized orthogonally. We also present numerical simulations of the system using a comprehensive model which incorporates all the relevant Zeeman sub-levels in the system, and identify means to improve the performance of the polarizer. A novel algorithm to compute the evolu...

… OF STANDARDS AND …, 1999

An investigation is made of a recently introduced quantum interferometric method capable of measuring polarization mode dispersion (PMD) on sub-femtosecond scales, without the usual interferometric stability problems associated with such small time scales. The technique makes use of the extreme temporal correlation of orthogonally polarized pairs of photons produced via type-II phase-matched spontaneous parametric down-conversion. When sent into a simple polarization interferometer these photon pairs produce a sharp interference feature seen in the coincidence rate. The PMD of a given sample is determined from the shift of that interference feature as the sample is inserted into the system. The stability and resolution of this technique is shown to be below 0.2 fs. We explore how this precision is improved by reducing the length of the down-conversion crystal and increasing the spectral band pass of the system.

IEEE Journal of Selected Topics in Quantum Electronics, 2000

We review waveform analysis and optical performance monitoring of ultrabroadband signals using a photonicchip-based radio-frequency spectrum analyzer. This approach offers the potential for fast integrated monitoring and characterization of signals with bandwidths beyond 1 THz.

As evidenced by this Volume, there has been a flurry of activity over the last decade on tailoring the dispersive properties of optical materials . What has captured the attention of the research community were some of the early results on creating spectral regions of large normal dispersion . Large normal dispersion results in extremely small group velocities, where the group velocity is the approximate speed at which a pulse of light propagates through a material. We denote the group velocity by υ g = c/n g , where c is the speed of light in vacuum and n g is known as the group index. In the early experiments, described in greater detail in Chapter *, a dilute gas of atoms is illuminated by a "control" or "coupling" beam whose frequency is tuned precisely to an optical transition of an atom. This control field modifies the absorption and dispersion properties of another atomic transition that share a common energy level. A narrow transparency window is created on this second transition -a process known as electromagnetically induced transparency (EIT) -and, within this window, υ g takes on extremely small values. Many experiments have now observed υ g ∼ 1 m/s or less, implying n g > 10 8 . This result is remarkable considering that fact that the refractive index n of a material rarely exceeds 3 in the visible part of the spectrum. What are the implications of such large group indices? What applications are enabled by this basic science discovery?

Microwave and Optical Technology Letters, 1992

the future telecommunication environment. 0 1992 John Wiley & Sons, Inc.

arXiv (Cornell University), 2016

We present a complete optoelectronic unit for polarization visualization, switching and control. The system is based on an FPGA unit and comprises: an acquisition unit containing an analog polarimeter and digital-to-analog converters; an FPGA capable of implementing an optimal algorithm for three-stage arbitrary polarization tracking; and an electronic driver with analog-to-digital converters capable of interfacing with Lithium-Niobate-based Polarization Controllers. The results, determined via simulation of real-parameter devices, show that fast polarization switch is achievable.