500 GHz Optical Sampler for Advancing Nonlinear Processing with Generalized Optical Pulses

The Center for Photonic Communication and Computing at Northwestern University is a world leader in quantum communications research, having developed many novel devices including the first fiber-based entangled photon source and the first telecom-band linear optics C-Not gate. We have also applied principles from our quantum research to the classical communications arena such as for all optical pulse regeneration or building fiber optical parametric oscillators. We have recently developed a series of methods to control quantum (and classical) optical signals at high speeds by manipulating optical pump pulses. Since quantum states are relatively fragile, these methods have strict performance requirements in terms of loss, scattered photons, and fidelity. We have demonstrated high speed quantum state switches that can be used for multiplexing/demultiplexing, generating single photon states, exceeding the classical limit on information efficiency per photon, and measuring high dimensional entanglement. We also have plans to demonstrate single mode photon detection of complex temporal modes− a previously unrealized fundamental optical detection method capable of measuring an arbitrary linear superposition of sub-photon quantum states. Such techniques can revolutionize quantum communications including quantum key distribution and low photon number communications. These quantum state manipulations rely upon precisely controlled pump pulses. While the quantum state is very sensitive to loss, the pump pulses that control them via a nonlinear interaction can be processed using lossy components such as an arbitrary optical waveform generator (OAWGs). OAWGs modify the spectral amplitude and phase of wide-band optical signals. The simplest and most robust technique for measuring the resulting pulses is an optical sampling method which mimics more common electrical sampling oscilloscopes but allows for an order of magnitude improvement in bandwidth. Our ability to control and analyze such interactions will be greatly enhanced by acquiring a 500 GHz optical sampler to better measure the pump pulse characteristics.