Optical Coupler 23522a

The instructor: Hồ Đức Tâm Linh

Hoàng Chung Phạm Gia Lương Mai Thị Quý Lệ Trần Thị Kiều Oanh

I. THEORY 1. Concept 2. Principle of Operation 3. Parameter 4. Types and fuction 5. Construction 6. Application 7. Fused Biconical Taper – FBT II. SIMULATION

1. OPTICAL COUPLER • Couplers are one of the most common devices in fibre systems, use to split, combine and diverged signals within systems. • α is coupling ration, with α = ½, coupler divided signal input into two equal parts at the output. Coupler in this case is called coupler 3 dB.

1. OPTICAL COUPLER • tive couplers is device allocate signals without change optical signal to electric signal. • Active couplers is electric device, can split or electric signal. • Directional Coupler carry light only direction. • Bidirectional Couplers carry light in either direction.

• Light “couples” from one wavelength to the other

The propagation mode of the combined waveguide • Electric fields outputs (Eo1 , Eo2), inputs (Ei1 , Ei2):

• When used only one active input:

• For a 3dB coupler the coupling length

must be chosen to satisfy:

3. PARAMETER • Excess Loss.

• Insertion Loss.

• Coupling Ratio.

3. PARAMETER • Uniformity.

• Polariation-dependent Loss. Loss < 0.15dB. • Directivity. • Near – end Crosstalk

3. PARAMETER • Return Loss

• Isolator.

4. OPTICAL COUPLER TYPES AND FUCTION Three port fibre Splitter: • Y Coupler simply divides the signal into two outputs.

• T Coupler fuctions the same as Y coupler, connect multiple terminals on a network.

4. OPTICAL COUPLER TYPES AND FUCTION

Three port fibre Combiner: use to combiner signals from two input to single output.

4. OPTICAL COUPLER TYPES AND FUCTION Tree Coupler: - One or two inputs and split it into multiple outputs and backward. - Tree couplers have been extensively used to split and mix optical signal in CATV, LANs and all other kinds of optical comunication systems.

4. OPTICAL COUPLER TYPES AND FUCTION

Four port fibre Coupler or X Coupler, use to split and signal, also know is Diverged Coupler.

4. OPTICAL COUPLER TYPES AND FUCTION • Star Fibre Coupler: mixing optical signals from all inputs and then distribute them among all outputs.

4. OPTICAL COUPLER TYPES AND FUCTION Comphare T Coupler and Star Coupler:

5. CONSTRUCTION OF COUPLER Fused coupler: The fibers are brought together and are then fused just like in a fusion splicer as seen in figure:

5. CONSTRUCTION OF COUPLER • A fused star coupler is made in a similar way

5. CONSTRUCTION OF COUPLER Mixing rod coupler: In mixing rod, the incoming light spreads out until it occupies the whole diameter of the fiber. And come out each receive some of the light.

5. CONSTRUCTION OF COUPLER Variable Coupler: A vernier adjustment allows precise positioning of the incoming fiber so that the light can be split accurately between the two output fibers to provide any required splitting ratio.

• Perform split/ optical signals .

• A star coupler nxn made by combining 3 dB coupler.

• Tap off a small portion of the light stream for monitoring purposes :  α close to 1(0.90 – 0.95) • Building blocks: Modulator Switches Filters Multiplexers/ demultiplexers

Ampifiers RAMAN use to coupler

Amplifiers EDFA use to Coupler

Internal struction of a 4 Channel WDM MUX and DEMUX

• FBT method is the most common way of

manufacturing coupler. • An optical fiber coupler is a device that distributes light from a main fiber into two or more fibers.

• Methods of fabricating: Fibre twisted, then spot fused under tension to form an elongated “biconical taper structure”.

Features of FBT:  low insertion loss  low polarization dependent loss  high return loss  environmentally stable

Applications  monitoring  testing  high speed systems

• Couplers are one of the most common devices in fibre systems, use to split, combine and diverged signals within systems. • There are two types Tree and Star Coupler. • Coupler has an important role in optical system.