An interview with Michael Jordan, outlining the applications and benefits of Corning Inc's Polarcor Glass Polarizers, conducted at Photonics West 2019.
What is a glass polarizer and why are they important?
There are a lot of different types of glass polarizers, for example solid glass, thin film, thin sheets and wire grid.
Glass polarizers are used in applications like telecoms. They are a small, thin, porous silicate glass substrate designed as a lens to absorb unwanted states of polarized light. Instead of reflecting it out like other polarizers do, Polarcor™ material absorbs those unwanted states of polarization due to the nature of how it is made.
In what industries are glass polarisers used?
Polarcor™ can be used in a lot of different industries, 90% of its use being in telecoms and datacoms. It is primarily a telecom and datacom material. We also have numerous customers in the aerospace and defense areas which utilize the Polarcor™ as a polarization filter. The medical industry uses Polarcor™ for the same purposes if they have tools requiring this.
The big use of our material in telecoms and datacoms is for free space optical isolators. Optical isolators are general and free space isolators that are put into transceivers as a one-way light valve. As your laser is emitting its optical signal to follow a path, it will usually go through a free space isolator, which helps protect the laser as no stray light can get back towards the laser cavity.
What challenges does the Polarcor™ help to overcome?
The biggest area Polarcor™ helps with is in the absorption of stray light. Lasers are notoriously sensitive to unwanted light, whether it is from its own reflection bouncing off something into the laser cavity, or from an external source. The polarizing filter then acts as a one way light valve to keep light from going back into the laser cavity and disrupting the signal that it is trying to emit.
Please outline the features of the Polarcor™. How does it compare to others on the market?
The Corning Polarcor™ product is a high extinction ratio, low insertion loss material. Extinction ratio is how much light it actually blocks (the block mode), and how much it lets through (the pass mode). Polarcor™ has an extremely high transmission value. It can be over 98.5 percent with two-sided AR coating on it, and still greater than 90% without the AR coating.
For example, your sunglasses are probably polarized. When wearing them everything becomes darker, because they are only allowing 25 percent or so of the light to come through your sunglasses. For Polarcor™ material this figure is over 90 percent all the time.
Therefore, with Polarcor™ the signal that a laser is putting out is getting through the material, but you get all the benefits of absorbing the stray light and getting rid of unwanted states of polarization that are unwanted in your optical system.
Why might someone need to make an UltraThin Polarcor™ compared to the high contrast Polarcor™?
The variations of the Polarcor™ product we have available on the market now are 0.5 millimeters thick, 0.2 millimeters thick, and our recently launched 0.12 millimeter thick polarizer. We also have an UltraThin polarizer.
The difference here depends on what you want to do from your system standpoint in terms of how rugged it needs to be. Most transceiver makers are in the 0.2 range and will use a 0.2 milimeter thick Polarcor™.
The 0.12, which is 40% smaller per substrate used, will allow a free space isolator to be about a third of the width that it is today. This gives transceiver makers and designers about 200 microns of space to realign something in their optical path. It gives them design flexibility in case they want to move or change the way the optical train in that transceiver is laid out.
The biggest reason is that the world of optics continues to shrink. As we have made this polarizer even smaller, the whole transceiver package can keep getting smaller. Think about a data center with lots of wires hanging out of the back. Our products allow you to get a larger number of wires in the same area. It increases the number of possibilities and possible connections, which data center companies can use to save money.
Our UltraThin product is a 30 millimeter, 30-micron thick product. It is about a third of the thickness of a sheet of paper and the thinnest available on the market today. It is extremely hard to handle and most customers that are using it use it in a very small chip - approximately one millimeter by one millimeter square size.
The Polarcor from Corning is now even thinner - Learn more
They will typically use that as a fiber lens filter, so they will attach it to the end of a fiber in whatever design set they might do. Because of its thinness, it does usually have a substantially lower contrast or extinction ratio. A lot of the time customers need enough contrast ratio, but they need it really, really thin because of how they are going to connect different things to the other side of that fiber.
About Michael Jordan
Michael Jordan is the Product Line Manager for Specialty Fiber and Polarcor for Corning Incorporated, Corning Optical Communications Division. Michael has been with Corning for over 20 years in various finance and business management roles across many of Corning’s divisions.
Michael focus as PLM, is to work directly with customers to help identify solutions to customer’s challenges as it relates to specialty fiber optic and polarization needs.
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