Fiber Bragg gratings are compo- nents for a wide range of applica- tions in   optical communications. The FBGs act there as in-fiber narrow band filters.
 
  Bragg gratings are imprinted into an optical fiber by a holographic process.   They can be produced with standard single mode fiber as well as with special   fibers, i. e. radiation mode suppressing fiber that is used to reduce thecladding mode loss.

§      DWDM technology for 2.5 Gbps and   10 Gbps systems
   

§      ASE filtering 
   

§      Add/Drop-multiplexers for 100GHz and   50GHz channel spacing

AOS provides FBGs with custom filter shapes as well as various FBG   connectors,

  housings, and packagings for a wide range of applications. Please refer to   the specification   sheet.
 
 

Wavelength

800 .. 1620nm

1280 .. 1340nm; 1520 ..1620nm

Reflectivity

5 .. 99.99%

FWHM

50GHz / 100GHz / 200GHz spacing
  or custom

Pass band

> +/- 0.12 nm

Insertion loss*

<0.1 dB *

PDL

<0.2 dB  

SNR adj. channel

>25 dB

>20 dB

SNR non-adj. channel

>30 dB

>25 dB

Termination

Bare fiber, FC/PC, FC/APC, ST, SC/PC, SC/APC, DIN, SMA

Packaging

3mm standard tube, 9mm athermal, boxed

Operating Temperature

0° .. 70°

*if radiation mode suppressed fiber is used

  Tunable Fiber Bragg gratings are a valuable option for all applications that   require flexibility in center wavelength (and/or frequency).
 
  The tuning setup consists of me- chanical assembly where the FBG is applied   to. The mechanics in- duces strain to the FBG, shifting its center wavelength   homogen- uously and chirp free. The spec- tral shape of the grating can be   specified as for the fixed FBGs, please use our specification   sheet.

  This time we offer 3 types of tunable FBG as standard:

• Manually tunable        FBG
          

• PC        controlled tunable FBG
          

• OEM version for system        integration (discontinued)

The PC controlled version and the OEM type are tuned by using an   internal stepper motor. The OEM type requires a stepper driver.

  The tunable FBGs are boxed and they can be equipped with a wide range of   connectors.
  As a special option we offer the devices equipped with switchable   adapters, enabling you to clean and/or change your adapters   easily. 
 

  A very common application of FBGs is the stabilization of DFB laser modules.   They are applicable to pump lasers for EDFAs 980nm / 1480nm as well as for   WDM mo- dules for the 1300nm / 1550nm band.
 
  On demand we are able to pro- duce also wavelength lockers at custom   wavelengths like 1064nm or 850nm, down to 800nm at this time, even with PM   fiber.
  The gratings can be designed for peak locking or for linear flank locking   (see examples below).

• EDFA pump laser wave­length locker
          

• DFB laser stabilisation for WDM        application
          

• In-fiber resonators for RAMAN fiber        lasers
          

• Tuneable laser modules

The   combination of wavelength locking FBGs with tunable setupsor athermal   packaging is also   available.

Center   wavelength (CW)

800 ..   1620nm

980nm;   1480nm; 1280 .. 1340nm; 1520 ..1620nm

Reflectivity

3 ..   50% (typical)

FWHM

0.08 ..   1.5 nm

Insertion   loss

<0.2 dB 

Proof   test

<100   kpsi (SM fiber)
  <50 kpsi (PM fiber)

Minimum   bending diameter

25 mm

Termination

Bare   fiber, FC/PC, FC/APC, ST, SC/PC, SC/APC, DIN, SMA

Operating   Temperature

5°C ..   120°C

Peak   locker FBG at 851.3 nm:

Flank   locker FBG at 193.4 GHz:

  This device is your perfect choice to filter signals with a very low FWHM,   down to 500 MHz in the optical domain. In opposite to standard FBG   components, the module does not reflect any signals. Hence it can be used   with laser applications without the need of an isolator.

• Narrow band signal transmission
          

• Brillouin scatter filtering
          

• ASE suppression
          

• Fiber laser mode separation
          

• Single photon counting / quantum        cryptography

• Tunability +/- 0.24nm
          

• Active wavelength stabilization
          

• Cascading of two or more devices for        multiple transmission lines
          

• Extreme noise suppression <50 dB        on request
          

• Outstanding spectral stability
          

The   Ultra narrow transmission filter allows to select signals with a narrow   bandwidth, while reliably blocking any other spectral components.

Available   as silver or black box

Wavelength

1525 ..   1610 nm

Line   width (FWHM)

0.005   .. 0.040 nm 
  0.5 .. 5.0 GHz

SNR

55 dB 

35 dB 

PDL

<0.2 dB  

Insertion   loss

<2.9 dB (*)

<2.0 dB (*)

Stability   @ 10° .. 45°C

+/- 2.5 pm

Operating   Temperature

10° ..   45°
  (custom upon request)

Termination

FC/PC,   FC/APC, ST, SC/PC, SC/APC, DIN, SMA 
  (3mm buffered fiber lead-outs upon request)

Packaging

Table   top box 
  (19" modular system)

Max.   input power

500 mW 
  (2 W upon request)

(*) The   IL might be higher at an FWHM that is smaller than 0.008nm (1 GHz)

The   transmission line with an FWHM of 1 Ghz. The filter does not provide a   reflected signal.

Dimensions   of a Ultra narrow-band transmission filter

  Using the technique of "chirped" (linear variation of the period   within the FBG structure) Fiber Bragg gratings, we are able to provide FBGs   with a very broad bandwidth and with a high rejection.
 
  We can provide a wide range of center wavelengths, bandwidths, and   reflectivities.

• WDM 1300/1550nm band rejection        filter
          

• ASE filtering, noise suppres- sion 
          

• In-fiber mirrors

  Due to their extended physical length, Broad Band FBGs require often a larger   packaging than normal FBGs. 
 

Wavelength

800 ..   1620nm

1535   ..1565nm

Reflectivity

5 ..   99.9%

FWHM

2 .. 70   nm

Insertion loss

<0.15 dB (*)

Termination

Bare   fiber, FC/PC, FC/APC, ST, SC/PC, SC/APC, DIN, SMA

Packaging

3mm   standard tube (lengths are varying), boxed

*On the FBG's lower wavelength side, ther   might be a significant higher IL due to radiation mode issues.

  Phase shifted Fiber Bragg gratings show a very narrow transmission band   within its reflection bandwidth. Using special structures, even multiple   transmission bands are possible.
 
  The phase shifted FBGs can be applied to an athermal setup or a temperature stabilization,   as well as to a tuning setup.

• Highly accurate wavelength        references (seeWavelength references)
          

• ASE filtering 
          

• Spectroscopy 
          

• Optical CDMA

  Phase shifted FBGs can also be applied to tuning or temperature stabilizing setups.
 
 

Wavelength

800 ..   1620nm

1280 ..   1340nm; 1520 ..1620nm

Reflectivity

50 ..   99.9% (*)

FWHM

custom

Transmission bandwidth (FWHM)

~ 0.005   .. ~ 0.100 nm (*)

Termination

Bare   fiber, FC/PC, FC/APC, ST, SC/PC, SC/APC, DIN, SMA, E2000

Packaging

3mm   standard tube, 9mm athermal, boxed, tunable

* Note: Higher values of reflectivity scale roughly with a   narrower bandwidth of pass band.

  Fiber Bragg gratings are sensitive against changes of temperature and strain.   The temperature caused wavelength shift for an FBG at 1550 nm is about   +10 pm/K. (Therefore standard FBGs are also used as temperature sensors see here).
 
  To prevent the gratings from that behaviour, a special package is used. Our   patent pending package consist of an assembly of materials with different   expansion coefficients which induces a small strain to the FBG, exactly dosed   to reduce the wavelength shift to a minimum.

• FBG's for 50/100/200 GHz DWDM        applications
          

• Wavelength referenced FBG's
          

• Add/Drop-multiplexers for 100GHz and        50GHz channel spacing
          

• Laser wavelength stabilising FBG

For an excellence long term stability, the package is epoxy-free   and immune against humidity.

Thermal dependency

<   0.7 pm/K, non-linear

<   1.5 pm/K, non-linear

Fibertype

Single   mode, 250/125 µm

Packaging

dia.   6.3 mm; length 55 mm (± 2mm)

Operating Temperature

0° ..   70° C