Online Store  About Us

What is the difference between a PC, APC and UPC  finish on a fiber optic connector and why would someone want to use one verses the other?

Whenever a connector is installed on the end of fiber, loss is incurred.  Some of this light loss is reflected directly back down the fiber towards the light source that generated it.  These back reflections, or Optical Return Loss (ORL), will damage the Laser Light Sources and also disrupt the transmitted signal.  To reduce back reflections, we can polish connector ferrules to different finishes.  A typical hand polished connector will measure at –30dB.  This polish is referred to as a PC or Physical Contact polish, which for some systems is considered too high of an ORL measurement.  To reduce the back reflection of a connector, we can machine polish it to SPC (Super Physical Contact) polish or UPC (Ultra Physical Contact) polish.  Industry standard is a minimum of –40dB for SPC Back reflection measurement and –50dB for UPC back reflection measurement.  If even less back reflection is required, an APC, or Angled Physical Contact polish, might be necessary.  An  APC connector has an 8º angle cut into the ferrule.  These connectors are identifiable by their green color.  An APC polished connector has an Industry Standard Minimum f –60dB ORL measurement. Abroad most CATV and telephone companies require the use of these low back reflection connectors.

 

Connector Ferrule Polishes: Performance and Compatibility
Alain Poirier,
http://www.exfo.com/en/support/WaveReview/January2003/WRarticle3.asp

FC, SC, ST, D4, DIN, and E2000 are currently some of the most widespread fiber-optic connectors. Although sizes, shapes and interlocking mechanisms can vary, one element is shared by all connectors: the ferrule. Since connector performance and compatibility depends on which ferrule polish is used, it is important to understand the differences between types of polish.

Four Types of Ferrule Polish
The ferrule (made of metal or ceramic) is the central part of the male connector. It is designed to both align and protect the fiber core during connection. The ferrule tip is polished to ensure a smooth finish on the fiber end. Polish can also minimize connector loss or backreflection, depending on the angle used.

There are four types of polish: PC, super PC (SPC), ultra PC (UPC) and angled PC (APC). Each one is illustrated below.

http://www.exfo.com/images/Support/WaveReview/January2003/article31.jpg

PC Polish
Designed to eliminate connector loss caused by gaps between two fiber ends, physical contact polish (PC) was the first type available (see Figures 1 and 2). Originally flat, PC ferrules were later slightly curved--a principle then applied to FC, SC, ST and D4 connectors--to optimize connection. The result: typical insertion loss values of 0.2 dB for singlemode fibers and maximum return loss values of 35 dB. The high return loss values motivated connector manufacturers to continue seeking better solutions.

APC and SPC Polishes
APC was the next polish developed (see Figure 3). For this connector, the ferrule end was cut to an 8° angle, eliminating almost all reflections at the connector end and giving a final return loss specification of 60 dB.

Early APC connectors did not deliver the repeatable performance of today's devices. Research on angled connectors therefore continued while other polishing methods were developed. SPC polish appeared next and was applied to FC and ST connectors, which provided return loss values of 40 dB while maintaining 0.2 dB insertion loss.

UPC Polish
Further work introduced UPC connectors, bringing return loss down to an impressive 55 dB in singlemode fibers. This performance was obtained by perfecting the polishing technique and adjusting the curvature at the ferrule end. Nowadays, UPC polish is available for almost all singlemode connectors--namely FC, SC, ST, DIN and E2000--but, unlike its predecessors, is not available for multimode fibers.

Compatibility
Due to their special angled design, APC connectors are not compatible with PC, SPC or UPC types. Joining an APC connector to a different connector type should be avoided, since this will cause more insertion and return loss than either connector would normally produce on its own.

PC, SPC and UPC connectors are all compatible and any cross between them will typically generate an insertion loss of 0.2 dB. Return loss is more difficult to predict when different polishes are cross-connected, but it generally falls somewhere between the individual return loss specifications for each polish. For example, an FC/SPC to FC/UPC connection might give an insertion loss of 0.2 dB and a return loss of approximately 58 dB.

Test instruments equipped with UPC connectors would therefore be capable of measuring PC, SPC and UPC systems without affecting their normal performance. On the other hand, test instruments equipped with PC connectors are not capable of measuring SPC and UPC systems, because the instrument connector's return loss could be greater than the return loss of the system itself.

============================================================================================

What is the difference between a PC, APC and UPC  finish on a fiber optic connector and why would someone want to use one verses the other?

Whenever a connector is installed on the end of fiber, loss is incurred.  Some of this light loss is reflected directly back down the fiber towards the light source that generated it.  These back reflections, or Optical Return Loss (ORL), will damage the Laser Light Sources and also disrupt the transmitted signal.  To reduce back reflections, we can polish connector ferrules to different finishes.  A typical hand polished connector will measure at –30dB.  This polish is referred to as a PC or Physical Contact polish, which for some systems is considered too high of an ORL measurement.  To reduce the back reflection of a connector, we can machine polish it to SPC (Super Physical Contact) polish or UPC (Ultra Physical Contact) polish.  Industry standard is a minimum of –40dB for SPC Back reflection measurement and –50dB for UPC back reflection measurement.  If even less back reflection is required, an APC, or Angled Physical Contact polish, might be necessary.  An  APC connector has an 8º angle cut into the ferrule.  These connectors are identifiable by their green color.  An APC polished connector has an Industry Standard Minimum f –60dB ORL measurement. Abroad most CATV and telephone companies require the use of these low back reflection connectors. PDR has the state of the art technology and equipments to produce higher standard Super, Ultra and Angled patchcords. PDR assemblies are prepared by highly skilled technicians and each assembly is checked to guarantee highest performance.

What is the difference between Singlemode and Multimode Patchcord and why would someone want to use one verses the other?

All fiber consist of a light carrying core in the center covered by an optical coating called cladding that traps light within the core. The difference between multimode and singlemode is the diameter of the fiber core. The core diameter is either 50 or 62.5 micron for multimode and 9 micron for Singlemode. Multimode patchcords are primarily used with LED sources for LAN and security systems. Its large core makes it easy to couple lots of light from inexpensive LED’s and it has adequate bandwidth for most premises applications. 
Singlemode patchcord has higher bandwidth and low attenuation because of its smaller core. But the smaller core needs expensive laser sources for efficient coupling, generally limiting its use to very higher bandwidth system used over long distances. Telecom and CATV system all use singlemode patchcords. Built to your specifications multimode and singlemode patchcords are available from PDR in simplex/Duplex style. All PDR patchcords are tested utilising the industry’s latest equipment and offer superior quality at low prices on all style of patchcords. PDR patchcord represents high quality, very loss and maximum performance. Singlemode Patchcords have yellow colour jacketing and multimode patchcords have orange or grey colour jacketing.

Top  

 

What is the difference between a SC/PC and SC/APC Adapter?

The most visible difference between the two adapters is color. Most singlemode SC/PC adapters are blue and SC/APC adapters are green. This allows for quick identification, especially when used in distribution panels so the end-user inserts the correct connector type. Often users cannot see the connector plugged in on the backside of the panels, therefore the color indicates the SC connector that’s required. SC connectors correspond with the adapter; most singlemode SC/APC connectors have green outer shells while singlemode SC/PC connectors have blue outer shells. SC/APC adapters use premium zirconia split sleeves to achieve the tightest tolerance possible providing critical alignment of the two angle polished ferrules. Whether it is a singlemode SC/PC or SC/APC connector be sure to choose a zirconia (ceramic) sleeve material rather than a phosphor bronze or polymer. The zirconia alignment sleeves have a tighter tolerance and better elasticity, maintaining tight tolerances after several matings.

 

 

Type-1 and type-2 14-pin laser pinout definition

(From http://www.thorlabs.com/NewGroupPage9_PF.cfm?Guide=10&Category_ID=97&ObjectGroup_ID=1558 )

Pin Assignment of the 14-pin Sockets

Pin to Connector Configuration for Type 1

Pin to Connector Configuration for Type 2

1

TEC Anode

1

Thermistor Ground

2

Thermistor

2

Thermistor

3

PD Anode

3

LD Cathode (DC)

4

PD Cathode

4

PD Anode

5

Thermistor Ground

5

PD Cathode

6

N.C.

6

TEC Anode

7

PD Cathode

7

TEC Cathode

8

PD Anode

8

LD Anode, Ground

9

LD Cathode

9

LD Anode, Ground

10

LD Anode, Ground

10

N.C.

11

LD Cathode

11

LD Anode, Ground

12

N.C.

12

LD Cathode (RF)

13

LD Anode, Ground

13

LD Anode, Ground

14

TEC Cathode

14

N.C.

.

.