Thorlabs' Ytterbia Optical Parametric Amplifier (OPA) is a femtosecond laser ideal for life science applications, such as three-photon microscopy, that require deep imaging depths, high signal-to-noise ratios, and minimal phototoxicity. Designed to be a robust one-box solution, this OPA has an integrated ytterbium fiber pump laser that converts femtosecond pulses at 1035 nm into pulses at 1650 nm by using white-light continuum generated in bulk media and optical parametric amplification (see schematic to the right); full access to the pump laser is also available. The OPA output beam, which has a tunable repetition rate from 1 to 4 MHz, delivers typical pulse energies of 500 nJ and pulse widths down to 50 fs at 1650 nm. 

Features

• Center Wavelength: 1650 ± 5 nm
  • Customizable between 1600 and 1700 nm
• Tunable Repetition Rate: 1 - 4 MHz
• Typical Pulse Energy: 500 nJ
• Flat Pulse Energy Scaling with Repetition Rate (See Specs Tab)
• Signal Output Pulses Down to 50 fs
• Integrated 1035 nm Ytterbium Femtosecond Fiber Laser for Increased Stability
• Bypass Port for Access to Full Ytterbium Femtosecond Fiber Laser Capabilities
• Control via Included Software for Hands-Free Operation (See Software Tab)
• Compact Footprint: 569.0 mm x 320.0 mm x 237.7 mm (22.40" x 12.60" x 9.36")

Applications

• Three-Photon (3P) Microscopy of Fluorescent Proteins (e.g., RCaMP, RFP, mCherry, tdTomato)
• Label-Free Deep-Tissue Imaging with Second Harmonic Generation (SHG) and Third Harmonic Generation (THG) Microscopy
• NIR Supercontinuum Generation
• Pump-Probe Spectroscopy

The FSLOPAX1 OPA's fixed-wavelength output can be customized to have a center wavelength between 1600 and 1700 nm to target specific regions of the NIR imaging window. In contrast to a wavelength tunable source, the Ytterbia OPA has reduced mechanical complexity, making it less susceptible to mechanical and performance instabilities while providing a cost-effective imaging solution.

Designed to have a compact footprint, the Ytterbia OPA vertically stacks the 1035 nm pump laser and the OPA within a single housing. This eliminates the need for beam routing on the optical table, which creates an optical system (US Patent 10,303,040) that is less sensitive to environmental changes. The front panel of the Ytterbia OPA features an output port for the OPA signal, as well as a bypass port that provides full access to the 1035 nm pump beam (see Front & Back Panels tab). For detailed specifications for the pump beam, please see the FSL1030X1 laser on the Ytterbium Femtosecond Fiber Laser web presentation.

Three CL5A mounting clamps are included with the laser head as well as two removable handles for easier set up. Both the OPA and bypass laser outputs have a beam height of 192.7 mm (7.58") marked on the side of the laser. Each laser also ships with a chiller and electronics unit, both of which are rack mountable. A full list of items shipped with each OPA can be found on the Shipping List tab.

Software
For hands-free operation and long-term reliability, the Ytterbia OPA features a user-friendly GUI that allows the user to power on the laser and easily switch between the Ytterbia OPA (OPA Mode) and 1035 nm femtosecond fiber laser (Bypass Mode). When operating in either mode, the repetition rate can be tuned via the software while the output pulse energy remains fixed. Please note when operating in the OPA mode the bypass output is disabled, and vice versa. See the Software tab for more information.

Applications to Three-Photon Microscopy
With a high peak power and tunable repetition rate, the Ytterbia OPA is optimized for three-photon microscopy, which requires efficient fluorescence excitation to achieve deep imaging depths. By including a tunable repetition rate, the user has the flexibility to adjust the imaging frame rate to accommodate the time scales of various processes or events, as well as control the average power incident on a sample to reduce heat-induced degradation.