Quadratic soliton mode-locked optical parametric oscillator in the mid-infrared
Abstract
Approved for Public ReleaseExtension of mode-locked laser and optical frequency comb technologies from the traditional near-infrared, (NIR) regime to new spectral regions is likely to trigger new research opportunities in both science and technology. The mid-infrar,ed (MIR) spectral region especially attracts great attention due to the presence of strong rovibrational transitions in many molecul,es, enabling detailed molecular fingerprinting. The MIR spectral region also contains two important atmospheric transmission windows, (3-5 and 8-12 micrometer) for applications like remote sensing, free-space communication, and night vision. MIR femtosecond lasers,have also found applications in soft-tissue medicine including laser microsurgery, and they serve as excellent pump sources for long,-wavelength infrared optical parametric oscillators (OPOs) and amplifiers.Early efforts to mode-lock OPO pumped by continuous-wave l,asers focused on active mode-locking with intracavity electro-optic modulator and acousto-optic modulator. The first attempts toward,s passively mode-locked OPOs were reported in 2013 and 2014 where the intracavity phase mismatched second harmonic generation (SHG),was utilized. Later demonstration and analysis showed that phase matched SHG can also promote the mode-locking action. A recent theo,retical study suggests that group velocity mismatch between the fundamental and SH fields results in domain wall locking and formati,on of mode-locked pulses. However, all these prior reports only demonstrate partially mode-locked OPOs with no stable femtosecond pu,lses and coherent comb spectra ever observed yet.The first research aim is to establish a new class of passively mode-locked MIR OPO, that takes advantage of the high-power cw Er3+:ZBLAN fiber lasers and the quadratic soliton mode-locking (QSML) principles my group, recently developed. The approach circumvents the performance degradation and system complexity of synchronously pumped OPO, thus en,abling new capabilities for MIR spectroscopy, atmospheric propagation, nonlinear optical phenomena, and strong-field physics.In addi,tion, existing technologies for ultrahigh-speed MIR spectroscopy is less mature compared to the NIR regime mainly because of the poo,r photodetection performance in the mid-infrared. MIR detector materials like mercury cadmium telluride (HgCdTe) or indium antimonid,e (InSb) exhibit obvious disadvantages such as limited detection sensitivity, small detection bandwidth, high cost, and the requirem,ent of liquid nitrogen cooling. Microbolometer technology enables room-temperature MIR detection, but the speed is inherently slower, due to the limited thermal response time. The single pixel detector can be integrated with Czerny-Turner monochromator or Michelson, interferometer to perform spectral-domain measurement. However, either the rotating grating or the moving arm limits the frame rate, to only Hz level. Alternatively, HgCdTe detector array enable kHz MIR spectroscopy by paralleldetection, but the spectral resolutio,n is limited by the large pixel separation and small pixel numbers. Finally, dual-comb MIR spectroscopy scans hundreds-of-nm-wide sp,ectrum at a frame rate up to hundreds of kHz, but high cost and system complexity limit its widespread applications.Th,rch aim is to establish a new difference-frequency-generation (DFG)-based MIR ultrahigh-speed time-lens spectral analyzer (MUTSA) to, fill up the technology vacancy. MUTSA can advance the MIR dynamic sensing capability and enable experiments in new areas such as th,e study of non-equilibrium mode-locking dynamics in QSML-OPO.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 05, 2022
- Source ID
- N000142212224
Entities
People
- Shu-Wei Huang
Organizations
- Office of Naval Research
- Regents of the University of Colorado
- United States Navy