Thorlabs Ytterbium Femtosecond Fiber Lasers

Overview

Thorlabs' Ytterbium FSL1030X1 and FSL1030X2 Femtosecond Fiber Lasers are high peak power, NIR lasers that emit clean, ultrafast pulses centered at 1030 nm. With ultrafast pulse widths, pulse energies on the order of µJ, and a user-tunable repetition rate from 1 to 11 MHz, these fiber lasers enable a wide range of applications, including multiphoton microscopy, optogenetics, and precision machining, especially in ophthalmology.

The high-energy pulses have typical temporal Strehl ratios of >0.90, corresponding to low temporal pedestals free from any picosecond background, thereby maximizing the usable output power per pulse. This is ideal for applications where reduced excitation powers are desirable to prevent heat-induced sample degradation and photobleaching, such as multiphoton stimulation in a neuroscience setting.

The FSL1030X1 offers a pulse energy of 12 µJ with pulse durations <250 fs (typical), while the FSL1030X2 offers a pulse energy of 2 µJ with pulse durations <130 fs (typical).

The FSL1030X1 laser is ideal for applications where energy is the dominant requirement, such as nonlinear frequency conversion with an emphasis on net output. The FSL1030X2 laser is better suited for applications where reduced pulse duration is the main lever to improve the user's signal level, such as ophthalmic tissue modification or multiphoton microscopy.

Key Specifications

Features

• Model for Higher Pulse Energy Applications (FSL1030X1)
• Model for Shorter Pulse Duration Applications (FSL1030X2)
• Ultrafast Pulse Width with Low Pulse Pedestal
• 1030 nm Center Wavelength
• User-Tunable Repetition Rate from 1-11 MHz
• >20 W Output Power at Max Rep Rate
• High Pulse Energy (See Table 1.1)
• Control via Downloadable Software for Hands-Free Operation (See Software Tab)
• Computer-Controlled Pulse Width Precompensation
• Compact Footprint: 569.0 mm x 320.0 mm x 237.7 mm

Applications

• Multiphoton Microscopy
• Photostimulated Optogenetics in Neuroscience
• Biological or Ophthalmic Tissue Machining
• Precision Micromachining of Tissues, Glass, and Plastics
• Optical Parametric Amplifier (OPA) Pumping
• White Light Supercontinuum Generation
• Non-Collinear Optical Parametric Amplifier (NOPA) Pumping
• Chemical Spectroscopy
• Terahertz Generation

Laser Safety

Safe practices and proper usage of safety equipment should be taken into consideration when operating lasers. The eye is susceptible to injury, even from very low levels of laser light. Thorlabs offers a range of laser safety accessories that can be used to reduce the risk of accidents or injuries. Laser emission in the visible and near infrared spectral ranges has the greatest potential for retinal injury, as the cornea and lens are transparent to those wavelengths, and the lens can focus the laser energy onto the retina.

Safe Practices and Light Safety Accessories

• Laser safety eyewear must be worn whenever working with Class 3 or 4 lasers.
• Regardless of laser class, Thorlabs recommends the use of laser safety eyewear whenever working with laser beams with non-negligible powers, since metallic tools such as screwdrivers can accidentally redirect a beam.
• Laser goggles designed for specific wavelengths should be clearly available near laser setups to protect the wearer from unintentional laser reflections.
• Goggles are marked with the wavelength range over which protection is afforded and the minimum optical density within that range.
• Laser Safety Curtains and Laser Safety Fabric shield other parts of the lab from high energy lasers.
• Blackout Materials can prevent direct or reflected light from leaving the experimental setup area.
• Thorlabs' Enclosure Systems can be used to contain optical setups to isolate or minimize laser hazards.
• A fiber-pigtailed laser should always be turned off ? before connecting it to or disconnecting it from another fiber, especially when the laser is at power levels above 10 mW.
• All beams should be terminated at the edge of the table, and laboratory doors should be closed whenever a laser is in use.
• Do not place laser beams at eye level.
• Carry out experiments on an optical table such that all laser beams travel horizontally.
• Remove unnecessary reflective items such as reflective jewelry (e.g., rings, watches, etc.) while working near the beam path.
• Be aware that lenses and other optical devices may reflect a portion of the incident beam from the front or rear surface.
• Operate a laser at the minimum power necessary for any operation.
• If possible, reduce the output power of a laser during alignment procedures.
• Use beam shutters and filters to reduce the beam power.
• Post appropriate warning signs or labels near laser setups or rooms.
• Use a laser sign with a lightbox if operating Class 3R or 4 lasers (i.e., lasers requiring the use of a safety interlock).
• Do not use Laser Viewing Cards in place of a proper Beam Trap.

Laser Classification

Lasers are categorized into different classes according to their ability to cause eye and other damage. The International Electrotechnical Commission (IEC) is a global organization that prepares and publishes international standards for all electrical, electronic, and related technologies. The IEC document 60825-1 outlines the safety of laser products. A description of each class of laser is given below:

All class 2 lasers (and higher) must display, in addition to the corresponding sign above, this triangular warning sign. ⚠️

Ytterbium Femtosecond Fiber Lasers

Pulse Calculations

Determining whether emission from a pulsed laser is compatible with a device or application can require referencing parameters that are not supplied by the laser's manufacturer. When this is the case, the necessary parameters can typically be calculated from the available information. Calculating peak pulse power, average power, pulse energy, and related parameters can be necessary to achieve desired outcomes including:

• Protecting biological samples from harm.
• Measuring the pulsed laser emission without damaging photodetectors and other sensors.
• Exciting fluorescence and non-linear effects in materials.

Pulsed laser radiation parameters are illustrated in Figure 170A and described in Table 170B. For quick reference, a list of equations is provided below. The document available for download provides this information, as well as an introduction to pulsed laser emission, an overview of relationships among the different parameters, and guidance for applying the calculations.

Equations:

Period and repetition rate are reciprocal:

At = 1 / frep and frep = 1 / At

Pulse energy calculated from average power:

E = Pavg * At

Average power calculated from pulse energy:

Pavg = E * frep

Peak pulse power estimated from pulse energy:

Ppeak = E / τ

Peak power and average power calculated from each other:

Ppeak = Pavg * At / τ and Pavg = Ppeak * τ / At

Peak power calculated from average power and duty cycle*:

Ppeak = Pavg / (τ / At) = Pavg / duty cycle

*Duty cycle (τ / At) is the fraction of time during which there is laser pulse emission.

Figure 170A. Parameters used to describe pulsed laser emission are indicated in this plot and described in Table 170B. Pulse energy (E) is the shaded area under the pulse curve. Pulse energy is, equivalently, the area of the diagonally hashed region.

Table 170B Pulse Parameters

Example Calculation:

Is it safe to use a detector with a specified maximum peak optical input power of 75 mW to measure the following pulsed laser emission?

Average Power: 1 mW
Repetition Rate: 85 MHz
Pulse Width: 10 fs

The energy per pulse:

E = Pavg / frep = (1 x 10⁻³ W) / (85 x 10⁶ Hz) = 1.18 x 10⁻¹¹ J = 11.8 pJ

Ppeak = Pavg / (frep * τ) = (1 x 10⁻³ W) / (85 x 10⁶ Hz * 10 x 10⁻¹⁵ s) = 1.18 x 10³ W = 1.18 kW

It is not safe to use the detector to measure this pulsed laser emission, since the peak power of the pulses is >5 orders of magnitude higher than the detector's maximum peak optical input power.