Abstract: An intracavity-doubled laser device, includes a pumping laser-diode, a Nd:YAG amplifying medium stimulated by a laser beam with a fundamental wavelength emitted by the laser diode, the output face of the amplifying medium being cut at the Brewster angle for the fundamental wavelength and a birefringent frequency-doubling KNbO3 crystal. The device further includes an isotropic medium (3), inserted between the input face (8) of the birefringent crystal, the amplifying medium (2) and the birefringent crystal (4), being fixed to each other such as to provide a monolithic resonant cavity. Furthermore, the crystal axis “c” of the birefringent crystal includes a non-zero angle <c with relation to the orthogonal direction of polarization of the fundamental wave defined by the Brewster surface.

Abstract: A RF-synchronization system includes a laser that creates pulse trains for synchronization. A modulation means transfers the timing information of the pulse train into an amplitude modulation of an optical or electronic system. A synchronization module changes the driving frequency of the modulation means until it reaches a phase-locked state with the pulse train.

Abstract: A laser frequency stabilizing device comprises a laser light producer operative to produce and emit a laser light containing a first and a second longitudinal mode light having different wavelengths; a spectrometer operative to spectrally decompose the laser light into the first longitudinal mode light and the second longitudinal mode light; a first detector operative to detect the light output signal from a absorption cell; a second and third detector operative to detect the signal intensity of the first and second longitudinal mode light; an actuator operative to change the resonant cavity length; a first drive controller operative to detect the saturated absorption signal from the light output signal detected at the first detector and control driving the actuator based on the saturated absorption signal; a second drive controller operative to control driving the actuator such that the signal intensity of the first longitudinal mode light detected at the second detector and the signal intensity of the secon

Abstract: Method and apparatus are disclosed that enable lasers to be stabilized in absolute frequency to high precision. The principle of operation is to: 1) lock the laser frequency to an etalon transmission resonance, 2) phase modulate the laser beam at a frequency corresponding to the free spectral range of the etalon and lock the phase modulated sidebands to the etalon resonances, and 3) lock the etalon free spectral range frequency to a stable reference frequency derived from, e.g., a stable crystal oscillator. The result is that the laser frequency is locked to an integer multiple of the reference frequency. The invention has applicability to numerous situations where a stable frequency must be provided at a specific value, and has further applicability to stabilizing multiple lasers in different locations to the same value.

Abstract: Electro-optic amplitude varying elements (AVEs) or electro-optic multi-function elements (MFEs) are integrated into signal channels of photonic integrated circuits (PICs) or at the output of such PICs to provide for various optical controlling and monitoring functions. In one case, such PIC signal channels may minimally include a laser source and a modulator (TxPIC) and in another case, may minimally include a photodetector to which channels, in either case, an AVE or an MFE may be added.

Abstract: A wavelength determining apparatus is disclosed. The wavelength determining apparatus includes a reflection block, a light detection block, and a determination block. The reflection block receives at least part of a laser light beam emitted from an external cavity type semiconductor laser and emits a reflected light beam that has a distribution of light intensities of fringes. The light detection block detects the intensity of the light beam reflected from the reflection block in two or more light reception positions. The determination block obtains a difference value of detection signals in the two or more light reception positions and determines the wavelength of the laser light beam on the basis of the difference value. The two or more light reception positions are arranged in the direction of which the fringes take place.

Abstract: The invention discloses an optical transmission module with digital adjustment and method thereof. The module includes a laser (21), a laser driver (22), an automatic power adjustment circuit (23), an automatic temperature adjustment circuit (24), a digital adjustment circuit (25) and a memory (26). The digital adjustment circuit, consisted of a digital-to-analog converter or a digital adjustment potentiometer, receives a digital adjustment signal and outputs, respectively, a extinction ratio adjustment signal and a cross point adjustment signal to the laser driver, an optical power adjustment signal to the automatic power adjustment circuit and an optical wavelength adjustment signal to the automatic temperature adjustment circuit. The memory stores data, using for on-line adjustment of the optical transmission module, at least including parameters of said optical transmission module and said laser emitting optical power parameters, to be reported upward.

Abstract: An injection seed of an injection locking type light source includes a broadband light source, a seed circulator receiving and transmitting a light from the light source to a seed optical filter passing only a desired wavelength band among the light beams from the light source and passing through the seed circulator, and an injection light source receiving a light beam of a specific wavelength band passing through the seed optical filter and outputting the wavelength-locked light beam without modulation to the seed optical filter at a predetermined power. The seed optical filter receives and outputs the wavelength-locked light beam from the injection light source to the seed circulator, and the seed circulator receives and outputs the wavelength-locked light beam as a seed beam. Since noise signal of a seed beam is small, noise signal of a final transmitting beam is also small and preferable for the high speed communication.

Abstract: A method of controlling a laser is provided for generating an optical output. The method includes the step of making a change to an electrical input to the laser so as to move the optical output of the laser towards a target frequency, and also includes the step of changing the temperature of the laser in relation to the change in the electrical input or the movement of the optical output. The method further includes the step of making further changes to the electrical input as the temperature of the laser is changed so as to maintain the optical output of the laser at the target frequency.

Abstract: A method and system is disclosed for making timing alignment for a data transmission system, the method comprising providing a reference clock signal with a first frequency to a multiplexer through a phase shifter, generating a multiplexed signal with a second frequency by the multiplexer, wherein the second frequency follows the first frequency and is higher than the first frequency by a predetermined proportion, sending the multiplexed signal to a modulator, and phase shifting the reference clock signal by the phase shifter before the reference clock signal is provided to the multiplexer, wherein a timing of the multiplexed signal at the second frequency level can be adjusted by adjusting a timing of the reference clock signal at the lower first frequency level.

Abstract: An automatic bias controller for an optical modulator is provided. The automatic bias controller comprises a driver for providing an electrical data signal to the modulator and a bias voltage source for providing a bias voltage to the modulator. A microprocessor provides a low frequency digital modulation signal, which is converted to an analogue modulation signal by a digital to analogue converter. The analogue modulation signal is applied to the bias voltage source (so as to modulate the bias voltage) or to the driver (so as to modulate the amplitude of the data signal). Intensity detectors for detecting the intensity of light emitted by the modulator are provided, and an analogue to digital converter converts the output of the intensity detectors to a digital intensity signal which is passed to the microprocessor. The digital intensity signal is analysed, and the bias voltage source instructed to adjust the bias voltage on the basis of the analysed signal.

Abstract: The objective of the present invention is to provide with is to provide with a tunable laser module capable of adequately detecting the decay of the large variation in the wavelength of the light and then operating the shutter. The tunable laser module 1 comprises a tunable laser source 11˜13 capable of emitting light with a wavelength defined by wavelength control signal, and following controllers 14˜17, 18˜23, 24˜28. A temperature controller 14˜17 operates to perform the control of the temperature of the tunable laser source 11˜13. A wavelength controller 18˜23 operates to perform the control of the wavelength of the light emanating from the tunable laser source 11˜13. A power controller 24˜28 operates to perform the control of the power of the tunable laser source 11˜13.

Abstract: A method and apparatus for accurately retrieving the position of an optical feature. The method uses the optical properties of biaxial crystals to conically refract the optical feature and transform the image of the optical feature to a circular ring structure. The position of the optical feature is then calculated by locating a center point associated with the circular ring structure.

Abstract: A method for a fiber optic device to conserve power includes turning off components in the fiber optic device and turning them back on when a detection signal is at a specified level. A method for a laser system to adjust a threshold level for signal detection includes generating a digital gain signal, amplifying at least one data signal with a gain based on the gain signal, comparing the at least one amplified data signal with a reference signal, and generating a signal based on the comparison. A method for a laser system to set error warnings includes receiving control bits that indicate if a host desires to be notified of certain error conditions and generating at least one signal based on the control bits to indicate at least one error condition.

Abstract: Electro-optic amplitude varying elements (AVEs) or electro-optic multi-function elements (MFEs) are integrated into signal channels of photonic integrated circuits (PICs) or at the output of such PICs to provide for various optical controlling and monitoring functions. In one case, such PIC signal channels may minimally include a laser source and a modulator (TxPIC) and in another case, may minimally include a photodetector to which channels, in either case, an AVE or an MFE may be added.

Abstract: Optical devices and techniques for using optical polarization of light to transmit through an optical path four times to quadruple a total delay in the light through the optical path.

Abstract: A frequency-stabilized laser device comprises an actuator arranged to vary the cavity length; an actuator driver arranged to apply a voltage to the actuator for changing displacement; a temperature detector arranged to detect the temperature on the cavity; a temperature adjuster arranged to heat or cool the cavity; a cavity temperature controller arranged to control the temperature adjuster based on a previously given instruction temperature and the temperature on the cavity detected at the temperature detector; and an instruction temperature corrector arranged to correct the instruction temperature given to the cavity temperature controller such that the voltage applied to the actuator remains almost constant.

Abstract: Electro-optic amplitude varying elements (AVEs) or electro-optic multi-function elements (MFEs) are integrated into signal channels of photonic integrated circuits (PICs) or at the output of such PICs to provide for various optical controlling and monitoring functions. In one case, such PIC signal channels may minimally include a laser source and a modulator (TxPIC) and in another case, may minimally include a photodetector to which channels, in either case, an AVE or an MFE may be added.

Abstract: A transmitter (11) emits a single wavelength optical signal and transmits this as a wavelength channel (13) in a compound multiplex signal through the WDM network. The receiver (12) selects the single wavelength optical signal (21) from the compound multiplex signal using a band-pass filter. A wavelength fit detector (15) determines a feedback signal by correlating variations of the amplitude of the received signal with variations of the traffic density. This feedback signal is then returned to the transmitter (11) via a back channel (16) and serves to tune the wavelength of the single wavelength optical signal.

Abstract: An optical apparatus including a tunable master laser from which all or some of a beam is injected into at least one “slave ” laser having a cavity with an amplifier medium and a dynamic holographic medium that forms a self-adapted spectral filter to maintain oscillation of the slave laser at a wavelength imposed by the master laser during injection after injection has stopped.

Abstract: A photonic integrated circuit (PIC) chip comprising an array of modulated sources, each providing a modulated signal output at a channel wavelength different from the channel wavelength of other modulated sources and a wavelength selective combiner having an input optically coupled to received all the signal outputs from the modulated sources and provide a combined output signal on an output waveguide from the chip. The modulated sources, combiner and output waveguide are all integrated on the same chip.

Abstract: In the laser system of the present invention, an acoustic grating (AG) established in an SBS cell by an initial laser pulse is forced into oscillation from noise. Since the process is nonlinear, SBS Phase Conjugation does not take place until a specific level is achieved based on several factors such as the physical conditions and the SBS media. The invention segments the initial laser pulse with a zonal lenslet array that produces a set of beams that have their foci distribute in space. By coupling this segmented lenslet array with a master lens, the separation of the foci from each other can be controlled. At a large separation distance each foci independently produces an associated AG. As each AG forms from a local noise source the coherence between the segmented beams has been lost. However, the master lens controls the entire focal envelope and hence the separation distance between the foci. Increasing the power of the master lens causes the separation between the foci to decrease.

Abstract: A photonic integrated circuit (PIC) chip comprising an array of modulated sources, each providing a modulated signal output at a channel wavelength different from the channel wavelength of other modulated sources and a wavelength selective combiner having an input optically coupled to received all the signal outputs from the modulated sources and provide a combined output signal on an output waveguide from the chip. The modulated sources, combiner and output waveguide are all integrated on the same chip.

Abstract: A semiconductor optical amplifier, an acousto-optic tunable filter, a phase shifter, a lens, and an internal etalon are arranged in a resonator. Outside the resonator, two lenses, two beam splitters, two photo-detectors, and an external etalon are arranged. The internal etalon is a quartz etalon and the external etalon is a crystal etalon. Therefore, the rate of change in transmission peak wavelength of the internal etalon to a temperature change is greater than that of the external etalon.

Abstract: A system of controlling a wavelength of a laser beam is provided. The system comprises a stage for supporting a wafer, an optical convergence unit for emitting the laser beam moving in an optical path toward the stage, and a specific wavelength detecting sensor. The specific wavelength detecting sensor is disposed between the optical convergence unit and the stage. It includes a laser beam absorbing structural body for absorbing a specific wavelength of the laser beam emitting toward the stage. A wavelength controlling unit for selectively controlling the wavelength of the laser beam is also provided.

Abstract: Protection methods and protection systems for semiconductor devices with diode junctions.

Abstract: A pulsed coherent fiber array laser system that includes a beam generating sub-system that provides a signal pulse beam having pulses of the desired duration that is split into several fiber channels. Optical leakage between the pulses in each split beam is measured and locked to a reference beam by a phase sensing circuit and phase adjusters so that the phase of each fiber pulsed beam is aligned with the phase of the reference beam. A pulse clipper or filter is employed to remove the pulses in the fiber beams so that they do not saturate the phase sensing circuit. The beam generating sub-system can employ any suitable combination of devices to generate the signal beam and the reference beam, including continuous wave master oscillators, amplitude modulators, frequency shifters, injection seed oscillators, Q-switched lasers, reference oscillators, frequency lockers, wavelength division multiplexers, time gated switches, etc.

Abstract: Compactness is preserved while enabling beam monitoring of optical properties of an output beam by employing a combination of reflection and diffraction. An input beam is reflected, divided using reflection/diffraction, and re-reflected. As a consequence, both a light source and one or more beam monitoring detectors may be disposed along a single side of an optical module. In one embodiment, an input beam is introduced from a first side of an optical module, is reflected by a 45 degree mirror, and is divided by a diffraction grating which redirects a minor portion of the beam energy back to the 45 degree mirror. Following the second reflection from the mirror, the returned portion of the beam is used to measure one or more optical properties.

Abstract: A method for generating a laser projection by employing a laser gain medium for receiving an optical input projection from a laser pump. The method further includes a step of employing a mode selection filter comprising an electro-optical (EO) tunable layer disposed between two parallel reflection plates for generating a laser of a resonant peak.

Abstract: An optical transmitter comprises an array of modulated sources having different operating wavelengths approximating a standardized wavelength grid and providing signal outputs of different wavelengths. Signal outputs of the modulated sources are optically coupled to inputs of the wavelength selective combiner to produce a combined signal output from the combiner. The wavelength selective combiner has a wavelength grid passband response approximating the wavelength grid of the standardized wavelength grid. A first wavelength tuning element is coupled to each of the modulated sources and a second wavelength tuning element is coupled to the wavelength selective combiner. A wavelength monitoring unit is coupled to receive a sampled portion the combined signal output from the wavelength selective combiner. A wavelength control system is coupled to the first and second wavelength tuning elements and to the wavelength monitoring unit to receive the sampled portion of the combined signal output.

Abstract: The invention relates to a method and device for controlling the amplitude of the wavelength spectrum of ultra-short light pulses emitted by multipass laser amplifiers. According to the invention, a programmable acousto-optic device (8) is introduced into a laser cavity of a multipass amplifier (10), in order to modify slightly the amplitude of the spectrum of the light pulse with each passage, owing to a collinear or quasi-collinear interaction between the light pulse and a sound beam, the result from the filtering being used on the non-diffracted direct light beam from the acousto-optic interaction.

Abstract: A MIR laser source that produces a fixed frequency output beam that is within the MIR range includes a QC gain media, and a wavelength dependent (“WD') feedback assembly that is spaced apart from the QC gain media and that cooperates with the QC gain media to form an external cavity. The WD feedback assembly may be used to precisely tune and control a lasing wavelength of the external cavity, and the position of the WD feedback assembly relative to the QC gain media may be fixed to maintain the precise lasing wavelength of the external cavity. With this design, each MIR laser source can be individually tuned to achieve the desired fixed frequency output beam that is within the MIR range.

Abstract: The present invention provides an optical transceiver that enables to reduce the crosstalk from the optical transmitter to the optical receiver. The regenerator of the optical transceiver includes two main amplifiers, a selector, a selector control, and a re-shaper for shaping the receiving signal selected by the selector. The first main amplifier provides a first amplifier and a delay circuit connected in upstream to the first amplifier. The second main amplifier provides a second amplifier and a delay circuit connected in downstream to the second amplifier. The selector selects, based on the phase difference between the receiving signal Rx and the transmitting signal Tx, the output from the first main amplifier or that from the second main amplifier.

Abstract: A photonic integrated circuit (PIC) chip comprising an array of modulated sources, each providing a modulated signal output at a channel wavelength different from the channel wavelength of other modulated sources and a wavelength selective combiner having an input optically coupled to received all the signal outputs from the modulated sources and provide a combined output signal on an output waveguide from the chip. The modulated sources, combiner and output waveguide are all integrated on the same chip.

Abstract: An optical transmitter comprises a monolithic transmitter photonic integrated circuit (TxPIC) chip that includes an array of modulated sources formed on the PIC chip and having different operating wavelengths approximating a standardized wavelength grid and providing signal outputs of different wavelengths. A wavelength selective combiner is formed on the PIC chip having a wavelength grid passband response approximating the wavelength grid of the standardized wavelength grid. The signal outputs of the modulated sources optically coupled to inputs of the wavelength selective combiner to produce a combined signal output from the combiner. A first wavelength tuning element coupled to each of the modulated sources and a second wavelength tuning element coupled to the wavelength selective combiner. A wavelength monitoring unit is coupled to the wavelength selective combiner to sample the combined signal output.

Abstract: A light source module including: an LD element outputting a laser light; a lens receiving the laser light and outputting a focused light; an optical filter having transmission wavelength characteristics, inputting the focused light, and outputting a transmitted light and a reflected light based on the transmission wavelength characteristics, a light-receiving element detecting the reflected light which passes thorough the lens and generating a detection signal; and a control unit configured to control an output wavelength of the LD element based on the detection signal.

Abstract: Various methods, systems, and apparatuses is described in which a passive-opticalnetwork includes a first multiplexer/demultiplexer, a second multiplexer/demultiplexer, a wavelength tracking component, and a transmission wavelength controller. The first multiplexer/demultiplexer is located in a first location. The second multiplexer/demultiplexer is located in a second location remote from the first location. The wavelength tracking component determines the difference between the transmission band of wavelengths of the first multiplexer/demultiplexer and the second multiplexer/demultiplexer to provide a control signal to match the transmission band of wavelengths of the first multiplexer/demultiplexer and the second multiplexer/demultiplexer. The transmission wavelength controller alters an operating parameter of the first multiplexer/demultiplexer based on the control signal to control the transmission band of wavelengths of the first multiplexer/demultiplexer.

Abstract: The present invention provides wavelength monitoring and/or control enabling size reduction and low power operation without requiring a complicated optical system in its wavelength monitoring and controlling mechanism. The measurement portion (1) measures temperature by a thermistor (5) in the measurement portion, and measures a bias current by using an LD drive current detecting circuit (6). The LD temperature, optical output and bias current are measured by the measurement portion. The relationship between the LD temperature and wavelengths or between the temperature, bias current and wavelengths is stored in a memory map of the storage portion (2). The central controlling portion (3) calculates wavelengths on the basis of the temperature and the bias current or the temperature information of the measurement portion, and the relationship between the LD temperature, bias current and wavelengths or between the temperature and wavelengths of the storage portion.

Abstract: An etalon functioning as a Fabry-Perot resonator is formed by bonding a quartz crystal bulk having a pair of Z-cut surfaces and a compensation bulk having a pair of Z-cut surfaces with one of the Z-cut surfaces of the quartz crystal bulk facing one of the Z-cut surfaces of the compensation bulk, reflection films being formed on the other of the Z-cut surfaces of the quartz crystal bulk and the other of the Z-cut surfaces of the compensation bulk, respectively. As for the compensation bulk, a LiCAF having a characteristic that (1/n)*(?n/?T)+? becomes negative, n being the refractive index, T the temperature and ? the linear expansion rate, and a ratio of the optical length of the quartz crystal bulk to that of the compensation bulk being approximately set to |(1/n)*(?n/?T)+?|:3×10?6.

Abstract: A laser apparatus having multiple laser devices coupled together. The laser devices include optical fibers with laser active regions. Each of the fibers has a reflector disposed at one end and is connected to a combiner on the other end. A laser pump device for each fiber provides pump energy to the laser active regions. Light propagating in the fibers interacts so as to form inphase states. The array of fibers may be coupled either in pairs or altogether between the reflector and the laser active region.

Abstract: An optical frequency comb generator includes a laser device arranged for generating input laser light having a predetermined input light frequency, a dielectric micro-resonator having a cavity exhibiting a third order nonlinearity, so that the micro-resonator is capable of optical parametric generation providing parametrically generated light, and a waveguide optically coupled to the micro-resonator, the waveguide being arranged for in-coupling the input laser light into the micro-resonator and out-coupling the parametrically generated light out of the micro-resonator, wherein the laser device, the waveguide and the micro-resonator being arranged for resonantly in-coupling the laser input light to a mode of the micro-resonator with a minimum power level so that an optical field inside the cavity exceeds a predetermined cascaded parametric oscillation threshold at which the parametrically generated light includes frequencies of frequency sidebands of the input light frequency and of the sidebands thereof.

Abstract: A device of detection of gas in trace amounts by a semiconductor laser coupled to a resonant optical cavity containing a chemical species to be analyzed. The device comprises a resonant optical cavity containing a chemical species to be analyzed; a semiconductor laser, coupled by optical feedback to the optical cavity and capable of being frequency-scanned; a means for adjusting the laser-cavity coupling rate; a means for finely adjusting the optical feedback phase; and a means for measuring the light transmitted by the cavity.

Abstract: A method and system is disclosed for making time alignment for a data transmission system. A first reference clock signal is provided to a first multiplexer coupled to a data modulator through a data driver, and a second reference clock signal is provided to a second multiplexer coupled to a clock modulator through a clock driver. Phase adjustment of the reference clock signal are conducted before the first reference clock signal is provided to the first multiplexer, wherein the phase adjustment aligns a timing of data modulated by the data modulator with a periodically modulated light source generated by the clock modulator.

Abstract: A method relating to the calibration of tuneable lasers is described. The method provides for the provision of correct control currents so as to achieve each of desired output frequencies from the laser. The correct currents are determined by forming a matrix of the output characteristics of the laser at specific tuning currents and processing that matrix to determine stable operating points within the matrix.

Abstract: A wavelength tunable laser unit has a laser mode selection, and is adapted to provide a laser signal in accordance with one or more laser control parameters. For operating the laser unit, the laser signal is swept in a wavelength range, a laser operation signal indicative of the laser unit's operation during the sweep is received, and the laser operation signal is analyzed for detecting an indication of a mode hop occurred in the generated laser signals during the sweep. At least one correction value is determined based on the detected mode hop indication, and at least one of the one or more laser control parameters, applicable for a next wavelength sweep, is modified based on the determined at least one correction value.

Abstract: A wavelength detector capable of distinguishing between the changes of a transverse mode and of a longitudinal mode of a laser light and thus detecting the change of the wavelength of the laser light with high accuracy is provided. In a wavelength detector 13: a diffraction grating 16 diffracts a laser light emerging from a laser light source 10; photodetectors 50a and 50b are positioned symmetrically with respect to a 0-order diffracted light diffracted by the diffraction grating 16; and light incidence surfaces 51a and 51b of the photodetectors 50a and 50b, respectively, have the same shape and are each divided into a plurality of areas.

Abstract: A laser apparatus is disclosed. An optical element receives at least a part of laser light emitted from a laser generation source and generates interference fringes. Each of first and second two-divided detectors has two detectors arranged in the direction of which the interference fringes appear. Each of the detectors detects an amount of light of the interference fringes. These two-divided detectors are spaced apart for an odd-number multiple of nearly ¼ period of interference fringes and disposed on a plane perpendicular to an optical path of the interference fringes. Each of first and second calculation sections calculates a first difference signal of detection signals of two detectors of the two-divided detector. A selection section selects one of the first and second difference signals. A determination section determines a wavelength of the laser light corresponding to a value of the difference signal selected from the first and second difference signals.

Abstract: A wavelength of an optical source is monitored by first and second adjacent detectors on a common base. A bulk reflective component has first and second partially reflective surfaces that respectively direct first and second portions of energy from the source to the first and second detectors. A wavelength discriminator is positioned between the first detector and first surface. An optical isolator downstream of the reflective component prevents radiation from the source and exiting the component from being coupled to the detectors and back to the source.

Abstract: An optical transceiver in which one or more bias currents provided to the laser driver are adjusted at cold temperatures such that transition speeds are reduced. A preliminary current generation circuit generates a preliminary current. In addition, a programmable cold temperature bias current compensation circuit draws a configurable amount of current from the preliminary current if the ambient temperature is below a threshold temperature to generate a final current. A laser driver bias current delivery circuit then provides at least one laser driver bias current to the laser driver. These delivered bias currents are dependent at least in part upon the final current. Accordingly, the bias currents provided to the laser current reduce the transition speed of the optical signal at low temperatures, thereby reducing jitter and electromagnetic interference, and allowing user control over the amount of compensation.

Abstract: An optical spread spectrum communication system includes a tunable laser which sequentially outputs optical signals having different wavelengths. The laser produces a frequency spectrum having a plurality of closely spaced modes relative to optical frequencies. The system further includes an optical modulator and a frequency synthesizer. The frequency synthesizer controls the optical modulator to allow specific modes from the frequency spectrum to pass through. Additionally, the system includes a tunable filter and a phase locked loop (PLL) control circuit. The PLL control circuit controls the filter to select specific channels. The selection of the specific modes by the modulator and the selection of channels by the tunable filter are performed independent of each other and are based on randomly assigned codes generated in accordance with one or more algorithms.