OE hlihhan / hlæhhan

Hello,

The only case of intervocalic <h> in Old English that I know of is <hlihhan> / <hlæhhan> "laugh". I recall seeing <hlihhan> explained as an onomatopoeic word (in other words, onomatopoeia accounts for its divergence from the pattern of Germanic *-h- > OE zero). But, <hlihhan> has at least partial cognates in other Germanic languages, including those that preserve intervocalic <h>: e.g., Goth. <hlahjan>.

Is the <-hh-> of OE <hlihhan> / <hlæhhan> generally thought to be onomatopoeic, or is it the expected outcome of earlier <-hj->?

Also, does the <-ch-> of German <lachen> have the same origin as the <-hh-> in its OE cognate?

Thanks