Coherent falls after forecasting quarterly revenue below estimates

** Shares of laser and optical devices maker Coherent COHR.N fall 17.4% to $94.20 in after-hours trading

** Company forecasts first-quarter revenue between $1.46 billion and $1.60 billion, the midpoint of which is below analysts' average estimate of $1.54 billion, according to data compiled by LSEG

** Separately, Coherent says it will sell its aerospace and defense business to private equity investor Advent for $400 million

** COHR reports Q4 adj. profit of $1.00/shr, vs analysts' average estimate of 91 cents/shr

** Company's quarterly revenue of $1.53 billion beats analysts' average expectation of $1.51 billion

** Up to last close, stock up 20.4% YTD