Silver–sodium ion exchange is a commonly used method for making waveguides in glass. This paper discusses two exchange media, KNO3:AgNO3 and AgNO3 in NaNO3:KNO3 which increase the flexibility of the process and decrease its cost. Exchange in the KNO3:AgNO3 can be performed at temperatures as low as 150°C, which is particularly useful for field assisted exchange. When exchange is performed in a NaNO3:KNO3 eutectic with small (≤5 mole %) added quantities of AgNO3, it is possible to control the guide’s surface index within the range Δn ≤ 0.01–0.09 and simultaneously allow the exchange to take place at temperatures as low as 220°C. Because the latter process requires very little of the relatively expensive AgNO3, it can reduce the cost of the process.
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