Fiber Gratings

Keywords: Fiber Bragg Gratings,Long Period Gratings, SMA905, D80, QBH

Feb 10, 2021
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Data Sheet

1. Fiber Bragg Gratings (FBGs) & Long Period Gratings (LPGs)

A fibre grating is a region of fibre whose refractive index has been permanently modified by exposing to light. Such exposure, if carried out with an interferometer or phase mask, allows a periodically varying refractive index grating or pattern to be “written” into the core of optical fibre. These “in-fibre” components are spectrally selective, which allow only specific wavelengths to be reflected or rejected, and are thus suitable for performing many tasks such as filtering and reflecting, in a highly efficient, low loss manner.

We have the capability to fabricate Fibre Bragg Gratings (FBGs) and Long-Period Gratings (LPGs). An in-house designed Fibre Grating Fabrication System with sophisticated software for fabrication process control has been setup, allowing various types of fibre gratings to be fabricated including complex grating structures such as Moiré, sampled, chirped and phase shift gratings. For the first time, we have also demonstrated the possibility of directly writing gratings on an optical fibre coated with standard off-the-shelf coating, with the resulting reflectivity and index change found to be equivalent to that of a fibre grating fabricated with bare fibre.

Our FBG system can make gratings with typical characteristics:

wavelength response is mainly in C band and L band;
depth can be higher than 30dB;
bandwidth is around 0.5-1 nm, depending on the depth of grating.
simple recoating

Applications

Notch filters
Optical multiplexers and demultiplexers
Optical circulators
Optical add-drop multiplexers (OADM)
Fiber Grating sensors sensitive to strain and temperature
FBGs used as reflectors in fiber lasers to make cavities

We can also fabricate customized fiber gratings! We are also open to heavily customised gratings, like tilted gratings or chirped gratings. Just let us know your requirements and the details in the ordering information below.

Ordering information:

Wavelength
Grating pitch
Depth
Bandwidths and tolerences
Chirp
Simple recoating

2. Gain Flattening Filters for C- and L- bands

Customized gain flattening profiles
Wide bands from 1520 nm to 1570 nm or 1560 nm to 1610 nm
Low ripple
Low insertion loss
Athermal packaging
High strength and reliability

Wavelength Range for C-band	1520 to 1570	nm
Wavelength Range for L-band	1560 to 1610	nm
Maximum Attenuation	8 dB or more on request
Attenuation Accuracy	< ± 5% of attenuation
Insertion Loss	< 0.5	dB
Operational Temperature Range	0 - 70°	C
Fiber	SMF-28 compatible, 1 meter
Package Dimensions	6.4 mm diameter x 64-95 mm L

3. Fiber Gratings for Laser Resonators and Sensors

Customized design
Variety of wavelengths
Optimized reflectivity and bandwidth
High strength and reliability

Wavelength Accuracy	< ±0.5	nm
Reflectivity	1 to 99.9	%
3-dB Reflection Bandwidth	0.2 to 1	nm
Grating Profile	Uniform or apodized
Insertion Loss	< 0.1	dB
Fiber	Corning SMF-28 (other fiber types available)
Recoating	Acrylate or custom
Pulling Strength	> 100	kpsi

4. 50 / 100 GHz DWDM Gratings

Near-square reflection spectral response
Optimized for 50 GHz or 100 GHz channel spacing
High center wavelength accuracy
Low channel crosstalk
Low insertion loss
Athermal package
High strength and reliability

	50 GHz	100 GHz
Center Wavelength and Accuracy	on ITU grid offset < ± 0.05 nm*
Cladding Mode Loss	< 0.5		dB
Reflection	> 99.9		%
Bandwidth	50	100	GHz
Bandwidth - 0.5 dB Reflection Bandwidth	> 0.2	> 0.3	nm
Bandwidth -30 dB Transmission Bandwidth	> 0.1	> 0.15	nm
Adjacent Channel Crosstalk	< - 25**	< - 30	dB
Non-adjacent Channel Crosstalk	< - 30	< - 30	dB
Insertion Loss	> 0.2		dB
Thermal Sensitivity	< 0.5		pm/°C
Operational Temperature Range	0 - 70		°C
Fiber	SMF-28 compatible
Package Dimensions	6.4 mm f × 55 mm L		mm