Abstract: A portable electronic device may include a housing having a wall defining an opening in the housing and at least a portion of four side surfaces of the portable electronic device. The portable electronic device may further include a display at least partially within the housing, a front cover positioned in the opening in the housing and over the display, the front cover defining a front surface, a peripheral side surface extending from the front surface and at least partially surrounded by the wall of the housing, and a notch that, together with a portion of the wall of the housing, defines an acoustic port of the portable electronic device. The electronic device may further include an acoustic port cover positioned at least partially in the acoustic port and a speaker at least partially within the housing and configured to direct sound through the acoustic port cover.

Abstract: An optical time distributor includes: a master clock including: a master comb; a transfer comb; and a free-space optical terminal; and a remote clock in optical communication with the master clock via a free space link and including: a remote comb that produces: a remote clock coherent optical pulse train output; a remote coherent optical pulse train; a free-space optical terminal in optical communication: with the remote comb; and with the free-space optical terminal of the master clock via the free space link, and that: receives the remote coherent optical pulse train from the remote comb; receives the master optical signal from the free-space optical terminal of the master clock; produces the remote optical signal in response to receipt of the remote coherent optical pulse train; and communicates the remote optical signal to the free-space optical terminal of the master clock.

Abstract: An optical time distributor includes: a master clock including: a master comb; a transfer comb; and a free-space optical terminal; and a remote clock in optical communication with the master clock via a free space link and including: a remote comb that produces: a remote clock coherent optical pulse train output; a remote coherent optical pulse train; a free-space optical terminal in optical communication: with the remote comb; and with the free-space optical terminal of the master clock via the free space link, and that: receives the remote coherent optical pulse train from the remote comb; receives the master optical signal from the free-space optical terminal of the master clock; produces the remote optical signal in response to receipt of the remote coherent optical pulse train; and communicates the remote optical signal to the free-space optical terminal of the master clock.