瀚（han）
Name meaning
瀚 (han) suggests vast water, desert-sea imagery and broad learning. In names it feels expansive, ambitious and scholarly.
Practical naming use
瀚 (han) is larger and more dramatic than 涵 (han). It is good when the desired name image is vastness: wide water, broad knowledge, frontier scale or intellectual range. It still needs discipline, because a vast character needs a steady partner to avoid sounding inflated.
Pair 瀚 (han) with culture, clarity or steadiness: 瀚文 (Hanwen), 瀚明 (Hanming), 瀚宇 (Hanyu) or 瀚安 (Hanan). Avoid another vastness word that makes the name overblown.
瀚文 (Hanwen): Han contributes vast water, vast learning; Wen adds culture, writing.
Reference
Cen Shen · A Song of White Snow Sending Magistrate Wu Back to the Capital
Historical / name-use references
张瀚 (Zhang Han)
Ming dynasty Jiajing jinshi and official; 瀚 (Han) appears directly in this recorded name, style name, title, or literary nickname.