Suddenly looking back, that person was in the dim light. Who wrote the poem?

Xin Qiji. According to the query on China Poetry Network.

1. Suddenly looking back to see that person in a dimly lit place is from Xin Qiji's "The Blue Jade Case on New Year's Eve", which means that when you look back suddenly, you find your sweetheart standing in the dark place.

2. Xin Qiji, whose original name was Tanfu, was later changed to You'an, and his middle-aged name was Jiaxuan. He was a native of Licheng County, Jinan Prefecture, Shandong East Road. He was an official, general, writer, and bold poet of the Southern Song Dynasty. He was known as the "Dragon of Ci". Together with Su Shi, he is called "Su Xin", and together with Li Qingzhao, he is called "Jinan Er'an".