Spectrum Emitted by the OCTAVIUS-85M

Features

• Spectral Bandwidth Up to 300 nm
• Temperature and Environmentally Stabilized Housing
• Robust Design with Compact Footprint

Thorlabs' Octavius 85 MHz Ti:Sapphire laser offers one of the broadest spectra commercially available. The spectrum of these laser systems is well suited for amplifier seeding, particularly for Optical Parametric Chirped Pulse Amplifiers (OPCPA), or use in pump / probe experiments. In addition, this version of the Octavius can also be used in linear and nonlinear biological probing and imaging applications.

Technology
The Octavius-85M and Octavius-85M-HP are soft aperture Kerr-lens mode-locked (KLM) Ti:Sa lasers. The laser cavity incorporates Dispersion Compensation Mirror (DCM) pairs, which are required for smooth, high-precision group delay control over an octave-wide bandwidth. The fabrication of these unique mirror pairs requires the optimization of a 150 coating layer design.

For the Octavius-85M, the high intensity of the intra-cavity circulating laser pulses and a carefully set temporal focus are used to create additional bandwidth outside of the Ti:Sa gain bandwidth through Self-Phase Modulation (SPM) in the Ti:Sa crystal. The extra bandwidth allows the detection of the Carrier Envelope (CE) frequency of the pulse train via a non-linear f-2f interferometer without prior broadening of the pulse using, for example, a Photonic-Crystal fiber. A typical f-2f beat note exhibits a signal-to-noise ratio of more than 30 dB when measured with 100 kHz resolution bandwidth.

Mechancial Design of the OCTAVIUS-85M
Ease of use and mechanical robustness were at the forefront of the design for the Octavius lasers. Unlike typical laser designs, which use traditional translation stages for tuning and alignment, the alignment of the Octavius is controlled via a unique flexure stage design that eliminates the various materials generally used for springs, bearings, and frames while still maintaining unprecedented accuracy and repeatability. Custom tooling and fixtures guarantee stress-free machining during production and therefore minimize drifts and misalignment of the laser cavity caused by stress relaxation.

Pump Laser
The Octavius 85 MHz Ti:Sapphire Oscillators come with an integrated pump laser. The pump laser is based on state-of-the-art Optically Pumped Semiconductor Laser (OPSL) technology, which allows for high compactness. As an option the laser is available without a pump laser; in this case, an input port can be used to direct the external pump laser into the oscillator.

Please contact applications@thorlabs.com for more information about these systems, customization options, or to request a quote.

Acknowledgements
The unique Dispersive Octave Spanning Mirror Pairs incorporated in this laser cavity were developed in close collaboration with Franz X. Kärtner, a professor at the Massachusetts Institute of Technology.

Laser Safety and Classification

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

• Thorlabs recommends the use of safety eyewear whenever working with laser beams with non-negligible powers (i.e., > Class 1) 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 Barriers and 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.
• 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 laser sign lightboxes 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 Laser Barrier or 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:

Class	Description	Warning Label
1	This class of laser is safe under all conditions of normal use, including use with optical instruments for intrabeam viewing. Lasers in this class do not emit radiation at levels that may cause injury during normal operation, and therefore the maximum permissible exposure (MPE) cannot be exceeded. Class 1 lasers can also include enclosed, high-power lasers where exposure to the radiation is not possible without opening or shutting down the laser.
1M	Class 1M lasers are safe except when used in conjunction with optical components such as telescopes and microscopes. Lasers belonging to this class emit large-diameter or divergent beams, and the MPE cannot normally be exceeded unless focusing or imaging optics are used to narrow the beam. However, if the beam is refocused, the hazard may be increased and the class may be changed accordingly.
2	Class 2 lasers, which are limited to 1 mW of visible continuous-wave radiation, are safe because the blink reflex will limit the exposure in the eye to 0.25 seconds. This category only applies to visible radiation (400 - 700 nm).
2M	Because of the blink reflex, this class of laser is classified as safe as long as the beam is not viewed through optical instruments. This laser class also applies to larger-diameter or diverging laser beams.
3R	Lasers in this class are considered safe as long as they are handled with restricted beam viewing. The MPE can be exceeded with this class of laser, however, this presents a low risk level to injury. Visible, continuous-wave lasers are limited to 5 mW of output power in this class.
3B	Class 3B lasers are hazardous to the eye if exposed directly. However, diffuse reflections are not harmful. Safe handling of devices in this class includes wearing protective eyewear where direct viewing of the laser beam may occur. In addition, laser safety signs lightboxes should be used with lasers that require a safety interlock so that the laser cannot be used without the safety light turning on. Class-3B lasers must be equipped with a key switch and a safety interlock.
4	This class of laser may cause damage to the skin, and also to the eye, even from the viewing of diffuse reflections. These hazards may also apply to indirect or non-specular reflections of the beam, even from apparently matte surfaces. Great care must be taken when handling these lasers. They also represent a fire risk, because they may ignite combustible material. Class 4 lasers must be equipped with a key switch and a safety interlock.
All class 2 lasers (and higher) must display, in addition to the corresponding sign above, this triangular warning sign