Manufacturing process for striae-free multicomponent chalcogenide glasses via multiple fining steps

A striae-free chalcogenide glass made by the method, comprising:

• loading chalcogenide glass precursors into an ampoule, sealing the ampoule, and placing the ampoule in a rocking furnace, wherein the rocking furnace comprises a top zone and a bottom zone, wherein the top and bottom zones are two independently controllable temperature zones;
• heating both the top and bottom zones at a rate of 3° C. per minute to a Step 1 temperature, wherein the Step 1 temperature is the same for both the top and bottom zones;
• maintaining the Step 1 temperature in the top and bottom zones while rocking the furnace at an inclination angle of ±45° for about 15 hours;
• increasing the temperature of the top zone at a rate of 3° C. per minute to a Step 3 top zone temperature and decreasing the temperature of the bottom zone at a rate of 3° C. per minute to a Step 3 bottom zone temperature while rocking the furnace at an inclination angle of ±45°, wherein there is a temperature gradient of 100° C. between the Step 3 top zone temperature and the Step 3 bottom zone temperature;
• setting the furnace to a vertical position and maintaining the Step 3 top zone temperature and the Step 3 bottom zone temperature for about 3 hours;
• decreasing the temperature of the top zone at a rate of 10° C. per minute to a Step 5 top zone temperature, decreasing the temperature of the bottom zone at a rate of 10° C. per minute to a Step 5 bottom zone temperature, and maintaining the Step 5 top zone temperature and Step 5 bottom zone temperature for about 3 hours, wherein the Step 5 top zone temperature is about 100° C. lower than the Step 3 top zone temperature, and wherein the Step 5 bottom zone temperature is about 100° C. lower than the Step 3 bottom zone temperature;
• decreasing the temperature of the top zone at a rate of 10° C. per minute to a Step 6 top zone temperature, decreasing the temperature of the bottom zone at a rate of 10° C. per minute to a Step 6 bottom zone temperature, and maintaining the Step 6 top zone temperature and Step 6 bottom zone temperature for about 3 hours, wherein the Step 6 top zone temperature is about 100° C. lower than the Step 5 top zone temperature, and wherein the Step 6 bottom zone temperature is about 100° C. lower than the Step 5 bottom zone temperature;
• decreasing the temperature of the top zone at a rate of 10° C. per minute to a Step 7 top zone temperature, decreasing the temperature of the bottom zone at a rate of 10° C. per minute to a Step 7 bottom zone temperature, and maintaining the Step 7 top zone temperature and Step 7 bottom zone temperature for about 30 minutes, wherein the Step 7 top zone temperature is at least 100° C. lower than the Step 6 top zone temperature, and wherein the Step 7 bottom zone temperature is at least 100° C. lower than the Step 6 bottom zone temperature;
• and
• removing the ampoule from the furnace and water quenching the glass.