A system of lasers which produces a single pulsed laser beam carrying many channels of digital information simultaneously. The information content of each laser output pulse is determined by the presence or absence of one or more input signal channel frequencies. The presence or absence of each frequency is provided by a plurality of low power CW lasers operating at different frequencies and which are selectively gated in a binary fashion by pulse coded digital input signals to provide digitized low power laser outputs in accordance with the digital input signals. The low level pulses of the various optical frequencies are combined and utilized to preload a relatively high power pulsed CO.sub.2 output laser. A pair of mirror assemblies are utilized to respectively combine the multifrequency channel pulses and transmit a single pulsed output laser beam generated by the pulsed output laser. The presence or absence of each frequency component in each output pulse is determined by the frequency components preloading the cavity modes of the pulsed high power output laser.
A first (1) and a second (6) narrowband laser device (1, 6) are each connected to an optical coupler means (3, 8) and also to each an input (13, 14) of a directional coupler (15). The coupler means (3, 8) have their respective outputs (5, 10) connected to a photo detector (18). The laser devices (1, 6) are each connected to their respective control circuit (17, 20). The control circuit (20) of the second laser device (6) is in turn connected to the output (19) of the photo diode (18) and to an exterior control signal (V2) with a frequency f.sub.0. Controlled by its control circuit (17) the first laser device (1) transmits a light signal (S1) with a fixed frequency f.sub.1, and the second laser device (6) transmits a light signal (S3) with a frequency f.sub.2. The photo detector (18) transmits a signal (V1) with a frequency f.sub.2 -f.sub.1 and the second control circuit (20) controls the second laser device (6) so that f.sub.2 -f.sub.1 =f.sub.0. An information carrying signal (V.sub.3) resets the directional coupler (15) and alternatingly switches the laser devices (1, 6) to the output (16) of the directional coupler (15). From this output there is sent a coherent frequency modulated signal S7 with the frequencies f.sub.1 and f.sub.2.
A technique for generating a large number of stabilized optical frequencies suitable for use in a wide variety of applications, including a multi-channel optical communications system, optical processing, optical computing, and heterodyne generation of stabilized RF frequencies. The technique contemplates stabilizing the cavity of a master laser and using the cavity modes as the carrier frequencies. Preferably, the modes are coupled, as by mode-locking, in order to prevent the modes from competing with each other for the laser gain, which would cause large amplitude variations. Since the cavity is stabilized, all of the cavity modes are stabilized. In one set of embodiments, the master laser is used directly as the laser source, the components at the different mode frequencies are spatially separated (demultiplexed) so that the component at each mode frequency can be individually amplified and modulated (e.g., by electro-optic (EO) modulators). In a second set of embodiments, a set of slave lasers is locked to respective modes. Each of these slave lasers may be individually modulated (e.g., by injection current modulation). The multifrequency source is useful even when the modes are not individually modulated, but serve only as heterodyne reference frequencies, as for example in radar applications.
An optical communications transceiver comprises a transmitter for transming a communications signal having at least two wavelengths and a receiver for concurrently detecting the communications signal on each wavelength. The receiver compares the data content of the communications signal received on each wavelength and detects errors in the received data. A display displays valid received data.
