This paper studies the diversity-multiplexing tradeoff (DMT) for the block fading optical wireless communication (OWC) channel when the number of transmit antennas is not less than that of receive antennas. Inputs in this channel represent optical intensities, and hence are real-valued and non-negative. Moreover, inputs are subject to a per-antenna peak-power and a total average-power constraint. Considering these input constraints and assuming the channel fading follows the negative exponential distribution, we establish the outage diversity and average error probability bounds by using a random truncated exponential coding argument. By these derived bounds, we characterize the optimal DMT curve. Interestingly, the DMT result is fundamentally different from its counterpart in traditional radio frequency (RF) channels. This is due to the fact that inputs in this channel are real-valued and bounded, while in RF channels inputs are usually complex-valued and unbounded.