In a small saucepan, boil pomegranate juice until reduced to 1/4 cup, 5 to 6 minutes. Let cool. Whisk in lemon juice, oil, salt, thyme, and pepper.
In a salad bowl, gently mix spinach, radicchio, pomegranate seeds, and hazelnuts with dressing. Divide among 6 plates.
Quarter pear and core. Thinly slice crosswise, then stack slices and cut in matchsticks. Arrange pear on salads.
*Splatter-free seeding: Cut a pomegranate into chunks. Put chunks in a bowl of water, and, working under water, use your hands to break seeds free from pith.
Note: Nutritional analysis is per serving.