High-sensitivity, MHz-rate, robust measurement of carrier-envelope phase of few-cycle ultrashort laser pulses by photocurrent detection in wide-band-gap semiconductors
Abstract
Carrier-envelope phase (CEP) is one of the fundamental parameters of femtosecond laser pulses that significantly affects ultrafast interaction of high-intensity ultrashort (up to 20 cycles) laser pulses with matter, e. g., nonlinear propagation and laser coupling to solid surfaces. A compact, calibrated device is highly needed for the applications of lasers that require measurement and control of CEP, including applications outside laboratory environments such as those of the DOD. Currently, electron photoemission from noble gases is the only practical approach for CEP measurements, but it is only feasible at low repetition rates (below 100 kHz), and requires vacuum chambers and stable conditions not affordable for out-of-lab environments. Methods to measure CEP by ultrafast effects in solids were proposed over the last 10 years, but they were impractical for routine measurements because of limited validity, low sensitivity, and lack of detailed scaling with laser parameters. Those issues result from poor understanding of the basic mechanism of ultrafast photo-effects in non-metal solids. Our recent results suggest that electron oscillations driven by intense ultrashort laser pulses serve as a universal mechanism of ultrafast light-to-current conversion in transparent crystals due to the capability to generate ultrashort, bias-free, net dc photocurrent pulses. Our preliminary estimations deliver a periodic scaling of the photocurrent with CEP of the driving laser pulses and a specific design of the proposed semiconductor detector that makes feasible a reliable detection of the photocurrent induced by nanojoule (nJ)laser pulses delivered at MHz repetition rates. The proposed approach can make a groundbreaking impact on many ultrafast laser technologies including the DOD applications by totally changing the current methods of CEPmeasurement. It promises a unique capability of CEP measurement at MHz repetition rates and low energy of laser pulses delivered by ultrafast oscillators prior to power amplification. To unlock these advances, in-depth experimental studies and simulations of ultrafast photocurrent generation coupled to design of the photocurrent detector are required. The proposed research addresses those issues by combining experimental, detector-design, and simulation efforts of 3 teams from the University of New Mexico led by Drs. Luke Emmert & Wolfgang Rudolph (ultrafast laser experiments; Dept. of Physics and Astronomy); Dr. Payman Zarkesh-Ha (photocurrent detector design; Dept. of Electrical and Computer Engineering); and Dr. Vitaly Gruzdev (Dept. of Physics and Astronomy; simulations and theory). This project builds the technological and scientific backgrounds of a new class of CEP detectors with advanced robustness, compactness, and sensitivity suitable for a broad range of ultrafast laser systems in labs and in the field including those operating at high repetition rate. Deliverables of this effort include a working detector of the ultrashort photocurrent pulses. This Research Abstract is approved for public release.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 05, 2021
- Source ID
- N000142112395
Entities
People
- Vitaly Gruzdev
Organizations
- Office of Naval Research
- United States Navy
- University of New Mexico