Together with our partner suppliers, AMS Technologies realizes optical gratings in various forms for a broad range of applications e.g. in optoelectronics, analytical, and defense industries.
Our high-efficiency volume Bragg gratings are based on a special multi-component silicate glass that enables fabrication of gratings with absolute diffraction efficiency >99%, thermal stability of +400°C, a laser damage threshold of up to 40 J/cm2, and tolerance to CW laser radiation in the near IR region at least up to several tens of kilowatts per square centimeter. Reflecting, transmitting and chirped volume Bragg gratings are available, providing narrow spectral selectivity down to 20 pm and narrow angular selectivity down to 100 μrad.
Our broad range of fiber Bragg gratings (FBGs) have many applications in optical communication, laser technology and sensing systems. Within our series of standard-types fiber Bragg gratings, you find uniform, apodized, chirped, and apodized-chirped fiber Bragg gratings, as well as fiber laser matched fiber Bragg grating pairs, tilted, and π-phase-shifted fiber Bragg gratings.
Optical sensors based on our femtosecond fiber Bragg gratings allow to monitor temperature, pressure, and deformation of such objects that previously hadn`t been eligible for fiber sensing. Our series of tunable fiber Bragg gratings is a good solution for many applications – including those requiring a corrected central Bragg wavelength. And our athermal packaged fiber Bragg gratings allow customers to achieve all advantages of fiber Bragg gratings, while preserving a high wavelength stability within a wide temperature range.
Within our series of specific application fiber Bragg gratings, you find wavelength locker FBGs, WDM ITU filter 100/200 GHz FBGs, Raman laser, and Fabry-Perot interferometer FBGs, as well as FBGs for hard environments, and radiation-hard FBGs.
All of our optical gratings’ configurations can be changed at the customer's request, please contact AMS Technologies to discuss an application-specific, customized optical grating solution tailored to your project’s requirements.
Complementing our optical gratings offering, AMS Technologies can supply a broad portfolio of fiber sensing equipment, including interrogation systems for measuring strain, pressure and temperature using fibers with Bragg Gratings inscribed. Our devices transform a single optical fiber into up to several thousand sensors, enabling seamless measurement and monitoring of large structures from aircraft wings to bridges or pipelines.
Optical gratings are intended for applications with light sources. AMS Technologies carries a broad portfolio of lasers and light sources, encompassing LED, SLED, broadband, ASE and supercontinuum light sources, as well as laser sources like DPSS lasers, diode lasers, gas lasers, OPOs and tunable lasers or other lasers and light sources – and also including an exceptionally broad portfolio of laser diodes, modules and systems for a wide variety of wavelengths and optical output powers.
We also carry a broad range of complementary optics products such as optical lenses, fiber collimators and focusers, lens holders and lens positioners as well as MWIR or LWIR thermal imaging assemblies. Other available precision optics include optical windows, prisms or optical filters. All featuring high precision, smallest tolerances (dimensional and angular) and special coatings for exotic wavelengths, even into the UV spectral range.
Additionally, we carry a broad range of complementary products such as optical mounts, rotary and translation stages, optical tables, breadboards and platforms, as well as a broad range of optical test and measurement equipment.
Optical gratings (also: diffraction gratings) are periodic structures used to diffract light. Optical gratings consist of parallel, line-like structures, where the grating constant is the period of the grating. If coherent light falls on a grating, the light diffracted at the individual grating lines interferes and forms an interference pattern. Monochromatic light is deflected in few different directions, with the angles of deflection depending on the grating constant and the wavelength, while polychromatic (e.g. white) light is spread out into its spectrum, similar to an optical prism.
Optical gratings are used in optical measuring devices to monochromatise radiation (monochromator) and to analyse spectra (optical spectrometer). Other examples of applications include frequency stabilisation of lasers, amplification of short high-power laser pulses, channel separation or merging in optical data transmission, and the use of optical gratings in optical fibers as sensor elements.
Optical Bragg gratings are transparent components in which periodic modulations of the refractive index are inscribed – usually by means of UV light. This Bragg structure forms an optical interference filter whose center wavelength satisfies the so-called Bragg condition. Wavelengths that lie within the filter bandwidth around this center wavelength are reflected. If the length of the grating is long enough, only a weak modulation of the refractive index around the Bragg wavelength can be sufficient for an approximately total reflection. All other wavelengths are only very slightly affected by the Bragg grating. With transmission and reflection being wavelength-dependent, a Bragg grating can be used as an optical filter.
Bragg gratings inscribed in a bulk piece of glass or polymer by UV radiation and subsequent heat treatment are called volume Bragg gratings. Due to the large interaction length and the use of special glass, it is possible to produce volume diffraction gratings with a diffraction efficiency of more than 99%, which are suitable for high temperatures and large optical radiation powers. Typical applications for volume Bragg gratings are narrow-band filters for lasers with low temperature dependence, stabilisation or tuning of the wavelength of laser light, or spectral beam combining.
In fiber Bragg gratings, individual layers inscribed in an optical fiber by means of UV light create a periodic modulation of the refractive index in the fiber core and thus an optical interference filter (bandstop) that reflects the light of a specific wavelength λ. Successive sections of length λ/2 are in turn composed of two λ/4 pieces with different refractive indices. Fresnel reflection of part of the injected amplitude occurs at each interface. The periodic change of the refractive index or the wave impedance causes the phase of the reflected wave to step either 0° or 180° at the end of each λ/4 piece. Multiple reflection results in constructive interference.
Here, the effective refractive index depends on the fiber geometry (core and cladding diameter), the difference in refractive indices and the wave modes. The spectral width of the filter’s wavelength band is determined by the length of the fiber Bragg grating and the refractive index difference between the adjacent regions. As this difference is not very large for manufacturing reasons, full amplitude cancellation is not possible with too few consecutive layers.
Fiber Bragg gratings are used, among other things, to filter out wavelength components from fiber laser light, to stabilise their wavelength, or to linearise the gain of fiber amplifiers. However, fiber Bragg gratings are also suitable as fiberoptic sensors. For example, it is possible to detect when a fiber is stretched or compressed – the deformation of the fiber changes the grating period and thus the Bragg wavelength of the grating. A fiber Bragg grating can also be used as a temperature sensor as the refractive index of the fiber material changes with temperature due to the thermo-optical effect.
The use of fiber Bragg gratings as a sensor is particularly attractive because a large number of such gratings can be inscribed in a single fiber at intervals of a few millimeters to a few kilometers, and the fiber can thus be used as a multipoint sensor that can be excited and read out via only one common interrogator unit. If the individual grating structures are arranged accordingly, each of these grating elements can also record other parameters such as acceleration, pressure or displacement – thus the fiber turns into a multifunctional sensor.
Alternative Terms: Fiber Bragg Grating; Volume Bragg Grating; Bragg Reflector; Bragg Grating Sensor Fiber; Diffraction Grating; Transmitting Bragg Grating; Reflecting Bragg Grating; Chirped Bragg Grating; Apodized Bragg Grating; Femtosecond Bragg Grating; Tilted Bragg Grating; Phase-shifted Bragg Grating; Tunable Bragg Grating