Difference Between OVPO Process and MCVD Process

OVPO and MCVD stand for Outside Vapor Phase Oxidation and Modified Chemical Vapor Deposition respectively. Both the OVPO and MCVD processes are fiber fabrication processes that are used to build and produce optical fibers. Optical fibers use the technology of light and are made as strands to transfer data.

OVPO Process vs MCVD Process

The main difference between the OVPO process and the MCVD process is that the OVPO process uses a mandrel or a bait rod in which the soot is a mixture of chemical halides vapors. On the other hand, the MCVD process uses a complex substrate tube without a rod into which soot formation occurs.

OVPO Process and MCVD

OVPO process is one of the very initial methods that are used for the fabrication of optical fibers. In this process, a traversing burner is used to heat a bait rod consisting of metal halide vapors and glass material on the other hand. It was a busy and inconvenient process.

MCVD process is a modified version for the fabrication of optical fibers. It uses a traversing burner that can move to any side to provide heat to a substrate tube of metal halide vapors. It also involves gas mixture to pass through the tube and finally exhausts after sufficient heating.

Comparison Table Between OVPO process and MCVD process

Parameters of ComparisonOVPO ProcessMCVD Process
OutputThe OVPO process makes a loss of about 20 decibels per kilometer for the optical fiber.MCVD process is used for producing low loss graded-index optical fibers.
DepositionThe OVPO process does the layer deposition of the content outside the fiber.The MCVD process does layer deposition inside the optical fiber.
Chemical ReactionOVPO method makes use of chemical hydrolysis reaction through the flame.The MCVD process uses the vapor dimension reaction for fabrication.
StepsOVPO method has four basic steps of soot deposition, its preform, perform sintering, and fiber drawing.The MCVD method is very convenient and quick enough with small steps.
InfluenceThe OVPO process for fabricating optical fibers was used in the initial stages and is a tough one.MCVD process is a modified method that has several advantages for convenience.

What is the OVPO Process?

OVPO process is abbreviated as Outside Vapor Phase Oxidation method and it is one of the four used methods for the fabrication of optical fibers. Optical fibers are fabricated through this process. However, it is a strict and tough process but it is a very popular method that has a big influence in the initial stages of developing technology through optical fibers.

When the process was implemented initially, it was found that the OVPO method has less than 20 decibels of loss of data per kilometer within the fiber. The basics of the OVPO process are simple and direct though tough and very strict. It requires a mixture of silicon dioxide compounds. These compound particles are togetherly called soot. There is a traversing flame burner used in the process that can move and heat a bait rod which is called a Mandel.

This rod has the deposition of the soot through the heat of the flame. Once the deposition starts, the soot is increased substantially layer by layer on the ceramic Mandel. Then, glass halide vapors are introduced to form the core and the cladding of the optical fiber. At about 1400 degrees Celsius temperature, the optical fibers are fabricated by taking off the glass rod.

What is the MCVD Process?

MCVD process is abbreviated as Modified Chemical Vapor Deposition process. It is often regarded as a more convenient method. This is because the MCVD method is a more modified version of normal processes for the fabrication of optical fibers. MCVD is a more advantageous process to fabricate graded-index optical fibers of very low loss.

This process has a more complex structure. It involves a substrate tube that is made up of glass silica and a traversing burner to put the flame on sufficient regions of the substrate tube. Besides the soot mixture of silicon dioxide compounds, a gas mixture is also passed within the substrate tube with the presence of soot particles. These are then exhausted out of the tube at a suitable time. Likewise, the substrate tube also has the capability of rotating like the bait rod.

The gas mixture introduced in the tube is a mixture of vapor halide gasses to react with soot. Now the soot is sintered on the glass rod using an oxyhydrogen torch. When the glass rod becomes sufficient enough for fabricating optical fibers, the vapor flow and suit deposition gets stopped manually and a high temperature is used with the glass rod to fabricate fiber.

Main Differences Between OVPO Process and MCVD Process

  1. The OVPO process uses the glass halide gasses only to form the core and the cladding of the fiber. On the other hand, the MCVD process uses core as gas halide vapor and cladding as the material of the soot.
  2. OVPO method does not involve the use of oxyhydrogen flame for sintering soot over glass rod. On the other hand, the MCVD process uses.
  3. The OVPO process uses soot as silicon dioxide. On the other hand, the MCVD process can also make use of phosphorus or germanium material.
  4. OVPO process uses 1400 degrees celsius temperature. On the other hand, the MCVD process uses 250 degrees celsius only.
  5. The OVPO method has a flame hydrolysis reaction. On the other hand, the MCVD method uses a vapor deposition reaction.


Since both the OVPO and MCVD processes are used for fabricating optical fibers, both have their charm and terms of use. The MCVD method of fabrication is more convenient and efficiently used these days. This is because the MCVD process uses significantly low temperature and throws out low loss graded-index fiber.

In this aspect, the OVPO process cannot match the fiber quality of the MCVD process. However, the reaction and contents used in the MCVD process are more complex than the OVPO process. The OVPO process is still very popular because of its initial implementation for fabricating optical fibers.


  1. https://allwise.yonsei.ac.kr/pdpl/subdir/equipments/paper/mcvd_01131071.pdf
  2. https://ieeexplore.ieee.org/abstract/document/1456096/
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