Did Japanese/Chinese warriors use exclusively katanas and other curved sword-type arms or did they use some type of broadswords like european did? I'm asking for great imperial and professional armies and not private knights and samurais.
The short answer is "no". They didn't exclusively use curved swords. The swords used included curved single-edged swords, straight single-edged swords, and straight double-edged swords. (There are some curved double-edged swords from the area as well, but these are rare enough so we can exclude them from standard military weapons.)
In both China and Japan, sword-armed ancient warriors/soldiers typically used short double-edged swords with large shields, analogous to Roman use of gladius and shield.
Chinese Warring States swords: https://commons.wikimedia.org/wiki/File:Iron_sword_and_two_bronze_swords,_Warring_States_Period.JPG
Japanese short double-edged sword (ken or tsurugi): https://commons.wikimedia.org/wiki/File:Ken_double_edge_straight_sword_Kofun_period_5th_century.jpg
These were followed in military use by two other types of swords. First, in China, in the late Warring States period through to the Han Dynasty, we see long double-edged bronze and iron/steel swords:
Bronze: https://commons.wikimedia.org/wiki/File:Qin_bronze_swords.jpg
Iron/steel: https://commons.wikimedia.org/wiki/File:Han_swords_146_cm.jpg
These don't appear to have been major military weapons for long. During the Han Dynasty, the straight single-edged sword became the common military sword:
Han Dynasty straight dao: https://i.pinimg.com/originals/12/7b/ba/127bba4cf7a54fc6e351de59252df5fa.jpg from Zhang Yun, The Complete Taiji Dao, Blue Snake Books, 2009, which includes a nice chapter on the history of the dao (i.e., single-edged Chinese sword): https://books.google.com/books?id=eQjLjqo774QC
Han Dynastry straight dao together with long double-edged sword and polearm head: https://commons.wikimedia.org/wiki/File:Han_iron_swords_and_halberd.jpg
Somewhat later, the straight single-edged sword displaced the double-edged sword as the main military sword in Japan (the Japanese sword above from the mid-Kofun Period is later than these Chinese examples immediately above - the single-edged short sword stayed in use later in Japan). By the late Kofun period, we see single-edged swords in common use in Japan, both short and long.
https://commons.wikimedia.org/wiki/File:Japanese_straight_swords_6th_7th_century_Kofun_period.jpg (These are somewhat similar in appearance to contempory Chinese swords, so the transition is probably at least partly due to Chinese influence.)
https://commons.wikimedia.org/wiki/File:Seven_stars_sword_Sitenoji_rotated.jpg
Into the Song Dynasty (China) and Heian Period (Japan), we see straight single-edged swords being usual, and during the Song Dynasty and Heian Period, curved single-edged swords largely replace them.
Song Dynasty straight dao: https://commons.wikimedia.org/wiki/File:Song_dao_hand_sword.jpg
Song Dynasty curved dao: https://i.imgur.com/9B9zBmh.png and https://i.imgur.com/iAlSbQt.png
Heian Period straight sword: http://www.kyohaku.go.jp/jp/img/dictio/kinkou/katana01_l.jpg (from http://www.kyohaku.go.jp/eng/dictio/kinkou/katana.html which has further info)
Heian Period curved swords: http://www.tnm.jp/modules/r_collection/index.php?controller=dtl&colid=F19933&lang=en and http://www.tnm.jp/modules/r_collection/index.php?controller=dtl&colid=F356&t=type&id=33
From then on, the main military swords in China and Japan (and Korea) were curved single-edged swords. These early Japanese curved swords were tachi, rather than katana. The katana, properly speaking, doesn't appear until about the 15th century. The main difference between the tachi and katana is the mountings - the tachi is suspended from the belt, edge-down, and the katana is worn with the scabbard tucked through the belt, edge-up. The tachi is also often longer (for use as a cavalry sword).
Double-edged swords and straight single-edged swords didn't disappear from military use in China and Korea (but did in Japan). The double-edged sword became much more of a civilian weapon and dress sword (so worn by officers rather than common soldiers), but still saw military use by the rank-and-file:
Ming Dynasty soldiers with double-edged sword and shield: https://2.bp.blogspot.com/-pX730TDEJyA/WOH4ENWYv0I/AAAAAAAADkA/IiTOqB7hZvIiLkSNZQcYiq6Cca4KxVNzACLcB/s1600/x_large_I6En_02ee000015c21263.jpg
Late Ming military manual presenting Korean techniques for the two-handed double-edged sword: https://static.wixstatic.com/media/065f0f_dcd62cbfca5342f7a0d2e97ec56583ed~mv2.gif - for more info on this manual: https://www.chineselongsword.com/straightsword
and had somewhat of a renaissance as a common weapon in late Qing militias.
The straight single-edged sword didn't vanish from use, either. Many Qing Dynasty dao are almost straight, or straight apart from a curved tip; these include cavalry dao in common use. Qing militias also used straight single-edged swords:
Finally, it should be noted that swords were often not the main weapons on the battlefield - the main weapons were usually spears and other polearms, and bows and crossbows (and later, guns).