In 4-quart saucepan, stir 1 cup sugar, the water, vodka and liqueur. Cut slit down center of vanilla bean; scrape out seeds. Discard bean; add seeds to mixture in saucepan. Heat to boiling over medium-high heat; add pears. Reduce heat to low. Cover loosely; simmer 25 to 45 minutes or until pears are tender. (Poaching time will vary depending on ripeness of pears.) Remove from heat. Let pears cool in liquid 1 hour.