Four-wave mixing (FWM) enables the generation and amplification of light in spectral regions where suitable fiber gain media are unavailable. The 1300 nm and 900 nm regions are of especially high interest for time-encoded (TICO) stimulated Raman scattering microscopy and spectro-temporal laser imaging by diffracted excitation (SLIDE) two-photon microscopy. We present a new, to the best of our knowledge, FWM setup where we shift the power of a home-built fully fiber-based master oscillator power amplifier (MOPA) at 1064 nm to the 1300-nm region of a rapidly wavelength-sweeping Fourier domain mode-locked (FDML) laser in a photonic crystal fiber (PCF) creating pulses in the 900-nm region. The resulting 900-nm light can be wavelength swept over 54 nm and has up to 2.5 kW (0.2 µJ) peak power and a narrow instantaneous spectral linewidth of 70 pm. The arbitrary pulse patterns of the MOPA and the fast wavelength tuning of the FDML laser (419 kHz) allow it to rapidly tune the FWM light enabling new and faster TICO-Raman microscopy, SLIDE imaging, and other applications.
A wavelength agile 900 nm 2.5 kW peak power fiber laser is created by four-wave mixing (FWM) in a photonic crystal fiber (PCF), while amplifying a 1300 nm Fourier-domain mode-locked (FDML) laser. The FWM process is pumped by a home-built 1064 nm master oscillator power amplifier (MOPA) laser and seeded by a home-built 1300 nm FDML laser, generating high power pulses at wavelengths, where amplification by active fiber media is difficult. The 900 nm pulses have a spectral linewidth of 70 pm, are tunable over 54 nm and have electronic pulse-to-pulse tuning capability. These pulses can be used for nonlinear imaging like two-photon or coherent anti-Stokes Raman microscopy (CARS) microscopy including spectro-temporal laser imaging by diffracted excitation (SLIDE) and time-encoded (Tico) stimulated Raman microscopy.
The system presented here is an evolution of the recently introduced spectro-temporal laser imaging by diffractive excitation (SLIDE) (1) microscopy technique. In order to excite endogenous fluorescence, a new flexible and fiberbased laser source at 780nm was developed. The fiber-based FDML-MOPA (2) was amplified to high peak and average powers by rare-earth Erbium fiber amplifiers. Afterwards, broadband quasi-phase-matched frequencydoubling using a Fan-out PPLN crystal was employed. The output is a 10 nm wide swept, pulsed laser around 780 nm with a pulse peak power of 150 W, 44 ps pulse duration and a pulse repetition rate of 82 MHz (250 pulses at 347 kHz sweep rate). The sweep rate is converted to line scans by a diffraction grating and sent to a microscope for two-photon excitation of UV-excited dyes or endogenous autofluorescence. For detection, the signal is captured with a 4 GS/s high speed digitization card leading to 2kHz fluorescence lifetime imaging (FLIM) acquisition.In this work, we present first images of 780nm SLIDE obtained at 2kHz frame-rate. Through the additional use of an piezo objective scanner, we are able to perform 3D imaging at 20Hz volume rate. We have also used this novel system for high-speed LiDAR imaging at a frequency of 2 kHz, using the recently introduced SLIDE-based timestretch LiDAR approach.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.