Abstract: The invention provides a semiconductor laser module which can suppress overcurrent flowing into a thermo-module, wherein the thermo-module (5) carries out a heating action when a reverse current flows from lead pin (16f) through lead pin (16a), and contrarily carries out a cooling action when a current flows from the lead pin (16a) through the lead pin (16f). An overcurrent limiting means (20) is provided, which can suppress overcurrent flowing into the thermo-module (5) in its heating direction. The overcurrent limiting circuit (20) is provided with a bypass line (21), a resistor (22), and a diode (23). When a current flows in the heating direction, the diode (23) is turned on, whereby the current is shunted to the thermo-module (5) and bypass line (21) for flow, and accordingly, the overcurrent flowing into the thermo-module (5) can be effectively suppressed.

Abstract: The present invention provides a circuit capable of driving a diode with multiple amounts of current with a low supply voltage without the requirement of alternating current coupling. The circuit provides for headroom voltage for the current sources allowing them to operate correctly without the requirement of external components such as inductors to provide coupling. The circuit may provide one of at least two different amounts of current depending upon the voltage of at least two inputs suitable for driving a vertical cavity surface emitting laser diode.

Abstract: A semiconductor laser driving circuit comprises a driving IC and a substrate on which the IC is mounted. The IC incorporates: a switching element for generating a driving signal; a high-potential power terminal and a low-potential power terminal for feeding supply voltage to the switching element; and a driving signal output terminal for outputting the driving signal generated at the switching element to an external device. These three terminals are disposed side by side at one of sides of a main body of the IC. The substrate incorporates three conductors to be connected to the three terminals. Two chip capacitors are disposed beside the one of the sides of the IC at which the three terminals are disposed. An end of each of the capacitors is connected to the high-potential power terminal while the other end is connected to the low-potential power terminal.

Abstract: A laser driver for generating drive waveforms that are suitable for driving a single VCSEL or an array of VCSELs. A digital controller is integrated into the laser driver and is utilized to initially program and selectively adjust during the operation of the driver one or more of the following VCSEL drive waveform parameters: (1) bias current, (2) modulation current, (3) negative peaking depth, and (4) negative peaking duration. The laser driver has an aging compensation mechanism for monitoring the age of the laser and for selectively adjusting the dc and ac parameters of the VCSEL drive waveform to compensate for the aging of the laser. The laser driver also has a temperature compensation mechanism for monitoring the temperature of the driver IC and selectively adjusting the dc and ac parameters of the VCSEL drive waveform to compensate for the changes in temperature.

Abstract: According to the present invention, there is provided a solid-state laser diode comprising: a laser diode for exciting a solid laser medium; a constant current source for supplying a constant current to the laser diode; voltage measurement unit for measuring a voltage at both ends of the laser diode; and abnormality detection unit for detecting an abnormality at the laser diode based on an output of the voltage measurement unit. Whereby a photodiode need not be arranged on the periphery of the solid laser medium and the laser diode, and an abnormality at the laser diode can be detected without increasing the size of the device and complicating the device and without deteriorating the laser emission efficiency.

Abstract: A laser driver circuit to provide a current signal to power a laser device is described. A bias current provided to the laser device may be changed while changes in the output power of a light signal from the laser device is monitored. A slope efficiency associated with the laser device may be determined based upon the changes in the bias current and changes in the output power.

Abstract: An automatic closed loop power control system is described for simultaneously adjusting an output power and an extinction ratio P1/P0 of a laser diode in order to maintain a desired average output power and a desired extinction ratio. The bias current component of a laser diode drive current is adjusted to compensate for changes in the average output power caused by ambient characteristics such as temperature and aging. Simultaneously, a modulation current component of the laser diode drive current is adjusted to maintain an extinction ratio of the laser diode output signal. The bias current and modulation current adjustments are based on the second order statistics of an average output power of the laser diode and a variance in the power output of the laser diode.

Abstract: A method and circuit for measuring the optical modulation amplitude in the operating region of a laser diode is described. The method utilises two measurements of OMA, each measurement being related to the slope in a specific portion of the operating region of the power/current characteristic curve of the laser diode. By combining the two measurement values, the invention provides a 1 measurement for OMA in the operating region of the laser diode that allows for the presence of a non-linear response in the region.

Abstract: The present invention is directed to a system and method which provide a Raman pump which is spectrally tailored in response to feedback from control structure associated with the Raman pump source. In certain embodiments of the present inventions, an incoherently beam combined laser (IBC) is utilized to provide a spectrally tailored Raman pump. In these embodiments, emitters in an emitter array are either individually addressable or block addressable to facilitate adjustment of emitter output power. By adjustment of the output power, the Raman pump may be spectrally tailored. The spectral tailoring can occur by employing suitable control algorithms to algorithms to dynamically maintain reasonably flat Raman gain.

Abstract: A laser unit has a laser mode selection and provides a laser signal in accordance to a laser control parameter. A plurality of pairs of values is determined for the laser control parameter and a laser operation parameter indicative of the laser unit's operation to provide the laser signal. A target operating point for the laser unit is derived from the determined pairs of values in conjunction with a model and a selection criterion for selecting the target operating point, wherein the model represents an assumed relationship between the laser control parameter and the laser operation parameter. A curve for the relationship between the laser control parameter and the laser operation parameter is approximated based on the determined pairs of values in conjunction with the model, the curve limited on at least one side having a defined boundary in a range where mode hopping is likely, and the target operating point selected on the approximated curve based on the selection criterion.

Abstract: An apparatus for and a method of controlling an output of a laser diode in an optical recording/reproducing apparatus. The apparatus includes a sampling circuit sampling a present power value output from the laser diode with a predetermined frequency, an arithmetic unit connected to the sampling circuit, outputting a control power value applied to the laser diode in response to the present power value output from the sampling circuit and a reference power value, and a controller connected to the sampling circuit and the arithmetic unit, generating control signals, which control the operations of the sampling circuit and the arithmetic unit.

Abstract: A pulse current component of a driving current is determined, based on a current-optical output coefficient derived using average optical output information of a semiconductor light-emitting element. A bias current component can be set by adjusting an average optical output of the semiconductor light-emitting element while changing the bias current component by the driving current including the determined pulse current component. Since the current-optical output coefficient can be derived based on the average optical output under wide conditions, both the pulse current component and the bias current component can be determined under the wide conditions and without using a quick-response light detector.

Abstract: A method for determining a condition of the laser system includes determining a change in a laser current from an initial value. A method for measuring a laser current includes determining a difference between the values of a power supply current, which is the value of the laser current. A method for measuring a transmitted power includes generating a first control signal that sets a magnitude of a bias current supplied to a laser, generating a second control signal that sets a of a modulation current supplied to the laser, and determining a difference between values of a high and a low transmitted powers. A method for measuring a received optical power includes determining a received OMA corresponding to the power signal, which is the transmitted OMA minus a known loss through a calibration fiber that couples the laser transmitter to the laser receiver.

Abstract: The semiconductor laser apparatus includes a semiconductor laser, a detection element for detecting the intensity of the output light from the semiconductor laser, an error detection circuit containing a gain controllable operation amplifying circuit and a gain-fixed type control amplifying circuit connected to a next stage to the gain controllable operation amplifying circuit, to which a semiconductor laser drive control signal is input and an output signal of the detection element is input as a negative feedback signal, for outputting an error signal corresponding to a difference between the two input signals, a high-frequency signal generating circuit for generating a high-frequency signal having a predetermined frequency, a high-frequency signal superimposing circuit for superimposing the high-frequency signal onto the output signal from the error detection circuit, and a laser drive circuit for supplying a drive current to the semiconductor laser on the basis of the output signal from the high-frequency

Abstract: The light-emitting module includes a semiconductor light-emitting device, a first optical detector for monitoring the magnitude of light emitted from the semiconductor device, a second optical detector for monitoring an oscillation wavelength of the semiconductor device, and an Etalon. The first detector is located in a position where the wavelength variation of the transmitted light from the Etalon is relatively small, while the second detector is located in a position where the wavelength variation of the transmitted light is relatively large. The geometrical size of the second detector along the first direction is wider than that along the second direction normal to the first direction; this thus enhances the efficiency of wavelength sensitivity.

Abstract: A laser control circuit comprises a temperature control circuit and a data processing circuit. The temperature control circuit adjusts the temperature of a laser diode by controlling a temperature regulator. The data processing circuit receives the output of a wavelength monitor. The data processing circuit first adjusts the, temperature of the laser diode to a temperature value previously associated with the target wavelength. Then the data processing circuit finely adjusts the temperature of the laser diode according to the output of the wavelength monitor. Because rough adjustment has been carried out, it is not necessary to change the wavelength significantly according to the output of the wavelength monitor. Therefore, the periodic wavelength dependence of the output of the wavelength monitor does not decrease the accuracy of the control.

Abstract: An optical margin testing system is provided for automatic power control loops. An optical circuit includes a laser diode and a monitor diode coupled to the automatic power control loop. A bias generator circuit generates a control signal. The control signal is applied to the automatic power control loop. The control signal enables an operation point of the laser diode to both increase and decrease by a set percentage value for optical margin testing. The bias generator circuit includes a tri-state receiver. An input signal is applied to the tri-state receiver for selecting one of a normal operational mode, an increased set percentage value operational mode, and a decreased set percentage value operational mode. A current mirror is coupled to the tri-state receiver provides the control signal that is applied to the automatic power control loop.

Abstract: A delay circuit delays an input signal. Further, a level shift circuit, which has a variable level shift amount, is provided between the delay circuit and an OR circuit, thereby making it possible to adjust a time during which a logic of active of the delayed signal is kept. Moreover, the OR circuit performs an OR operation of the input signal and an output signal of the level shift circuit so as to obtain a signal of an OR logic, which drives a light emitting element. With this arrangement, the level shift amount is adjusted in response to a control signal externally supplied, in an optical transmitter arranged such that the input signal and output light emitted from the light emitting element with a delay in the emission, have the equal duty ratio. In this way, property unevenness among finished products of the light emitting element is cancelled out. Thus, it is possible to drive the light emitting element at a higher speed.

Abstract: A method for controlling a modulation current and a bias current of a laser driver includes generating a differential signal that has a voltage offset, for setting the modulation current, over a pair of differential inputs from a pre-driver circuit to a laser driver circuit. A voltage is generated for setting the bias current over a bias/monitor pin from the pre-driver circuit to the laser driver circuit. The voltage offset is sensed at the laser driver circuit and the modulation current is set based on the voltage offset. The voltage is sensed at the laser driver circuit and the bias current is set based on the voltage. A photo current is delivered over the bias/monitor pin from the laser driver circuit to the pre-driver circuit wherein no interaction occurs between the photo current and the voltage. The voltage is then modified based on the photo current.

Abstract: An optical transmitter is equipped with a laser diode and a light detector provided on a packaging base, in which the light detector has a semiconductor substrate side arranged on a packaging base side, a semiconductor junction plane, a side surface which is roughly orthogonal to the semiconductor junction plane, and a facing surface which faces the side surface, wherein the facing surface is partially or completely inclined to reflect the output light from the laser diode incident from the side surface to the semiconductor junction plane of the light detector.

Abstract: Optical logic circuits are based on lazing semiconductor optical amplifiers, such as vertical lazing semiconductor optical amplifiers. For example, one or more VLSOAs with selected depletion thresholds are combined to form various optical logic devices.

Abstract: A laser system includes a pump source that produces a first output. The pump source has a feedback loop with a first summing junction and a first command that has step quantization or digitized set point. An output device is coupled to the pump source to receive the first output and produce a second output. A feedback loop is coupled to the first summing junction. The feedback loop includes a second summing junction coupled to at least a portion of the second output. The second summing junction receives a second command and provides an input to the first summing junction. The feedback loop reduces the step quantization from the first output to provide finer control step of a property of the second output.

Abstract: A tunable laser comprising a laser source for providing light with a wavelength along an optical path. A diffractive element is positioned in the optical path and spaced from the laser source for redirecting the light received from the laser source. A reflective element is positioned in the optical path and spaced from the diffractive element for receiving the light redirected by the diffractive element and for further redirecting the light back along the optical path to the reflective element. The diffractive element receives the light further redirected by the reflective element and returns the light along the optical path to the laser source. The optical path created by the laser source, the diffractive element and the reflective element causes the light to lase at the wavelength. At least one microactuator is coupled to one of the diffractive element and the reflective element for moving such element to select the wavelength of the light.

Abstract: The invention relates to an electrical circuit for a directly modulated semiconductor radiation source having a semiconductor radiation source, to which a modulated current is supplied in a manner dependent on a digital data signal, the falling signal edge of said current exhibiting peaking. According to the invention, provision is made of circuit means which are connected to an electrical contact point of the circuit and which reduce peaking of the falling signal edge when a predetermined value of the forward voltage across the semiconductor radiation source is undershot. This allows higher data rates to be achieved.

Abstract: A laser power control circuit that is constituted by CMOS transistors reduces variations in a laser power that is emitted from a semiconductor laser, which are caused by a mismatch of the transistors. An offset amount of a differential amplifier is digitally calculated using an A/D converter that is located on the same chip, and a voltage value of a variable voltage source is controlled for applying a voltage in a direction opposite to the offset voltage of the differential amplifier to correct the offset voltage of the laser power control circuit, thereby reducing the variations in the laser power emitted from the semiconductor laser.

Abstract: Apparatus and methods to control laser duty cycle are disclosed. According to one example, a driver circuit may include a duty cycle adjustment circuit, an output stage configured to receive an input signal having a duty cycle and a replica output stage configured to receive the input signal and to produce an output signal that is coupled to a duty cycle adjustment circuit. In such an arrangement, the duty cycle adjustment circuit is configured to affect the duty cycle of the input signal.

Abstract: A driving method of a semiconductor laser having an active layer region, a phase adjustment region and a distributed Bragg reflector region includes the steps of: calculating an average value of multipulse modulation currents modulated between a peak current and a bottom current input to said active layer region; calculating a difference between the average value of the multipulse modulation currents and a bias current input to the active layer region; and applying a first compensation current to the phase adjustment region when the multipulse modulation current is input to the active layer region, and applying a second compensation current corresponding to the difference to the phase adjustment region when the bias current is input to the active layer region.

Abstract: An apparatus and method for providing cooling to a magnetic circuit element having a magnetic core disposed around a centrally located core support member having at least one core support member wall is disclosed which may comprise a core support coolant inlet; a core support coolant outlet; a plurality of interconnected coolant flow passages contained within the core support member wall and interconnected and arranged to pass coolant from one coolant flow passage to the next within the core support member wall along a coolant flow path within at least a substantial portion of the core support member wall from the core support coolant inlet to the core support coolant outlet.

Abstract: Method and system for providing stabilization techniques for high repetition rate gas discharge lasers with active loads provided in the discharge circuitry design which may include a resistance provided in the discharge circuitry.

Abstract: Apparatus for digitally driving a laser in a passive optical network includes a programmable current source having an output terminal connected to supply current to the laser. The programmable current source includes a plurality of output pins, each of the outputs pins has a voltage thereon, all of the output pins are connected to the output terminal, and one or more of the output pins is connected to the output terminal through a resistor. A controller supplies a digital control signal to the programmable current source to specify which of the output pins are to be turned on, to thereby determine the magnitude of a current supplied to the laser from the output terminal.

Abstract: The invention is directed to a laser diode assembly having a laser diode and a support, whereon the laser diode is arranged or formed in one single piece. The laser diode assembly further includes a coupling capacitor integral therewith, wherein the laser diode is subjected to the action of a laser driver circuit via the coupling capacitor associated with the assembly. The invention is also directed to a device for operating a laser diode, wherein the device includes a coupling capacitor integral with a laser diode assembly. The invention enables a reduction in the number of coupling paths between a laser driver circuit and a laser diode assembly, thereby reducing the occurrence of parasitic elements.

Abstract: A laser system including a controller for monitoring and controlling various functions of a laser assembly. The laser controller may include a wavelength tuning circuit for adjusting and locking the wavelength of the external cavity. To perform various monitoring and control functions, the controller may include circuitry for monitoring various parameters associated with operation of the laser, such as temperature indicating signals and/or signals from light detectors such as photodiodes.

Abstract: An all-silicon nonlinear transmission line (NLTL) is integrated with a pulse-forming circuit in the form of a reverse-biased diode. Relatively short, e.g., 27 ps, optical signals can be generated from the all-silicon NLTL circuit by laser modulation of the electrical NTLT output in an electro-optical system.

Abstract: A lithography laser system for incorporating with a semiconductor processing system includes a discharge chamber filled with a laser gas including molecular fluorine and a buffer gas, multiple electrodes within the discharge chamber and connected with a discharge circuit for energizing the laser gas, a resonator including the discharge chamber for generating a laser beam, and a processor. The processor runs an energy control algorithm and sends a signal to the discharge circuit based on said algorithm to apply electrical pulses to the electrodes so that the laser beam exiting the laser system has a specified first energy distribution over a group of pulses. The energy control algorithm is based upon a second energy distribution previously determined of a substantially same pattern of pulses as the group of pulses having the first energy distribution.

Abstract: A ceramic substrate is provided through a stem of a can-package, the desired number of wirings including the high speed signal wirings are formed on this ceramic substrate and the necessary electronic components other than a light-emitting/photosensitive element such as driver LSI and amplifying LSI or the like are also accommodated within the can-package.

Abstract: A light beam detection device includes a light-receiving element for receiving a light beam and outputting a detection signal. A light detection circuit generates and outputs a light-emission signal based on the detection signal. A light-emitting element emits light based on the light-emission signal. The light-receiving element and the light-emitting element are arranged on a detection member. A supporting member supports the detection member. A driving device moves the supporting member in a reciprocative manner in an X axis direction and a Y axis direction to form a detection region with the detection member. The light-emitting means forms an afterimage on the detection region when the light beam irradiates the detection region.

Abstract: A method of controlling a tuneable laser that has been characterized with respect to one or more suitable laser operation points. Each operation point is determined by the manner in which the different laser sections are controlled, in order to operate the laser at a predetermined operation point. The voltage across the different laser section is determined for different operation points when controlling the laser, and the voltages across the different laser sections are held constant when the laser is in operation to maintain a predetermined operation point.

Abstract: In a gas laser device, a compensation time according to electric charges accumulated in a charging capacitor is calculated and, when the compensation time lapsed from a time when an outer trigger was input, a compensation trigger is output to a semiconductor switch to electrically connect the charging capacitor and a first-stage capacitor, whereby a time between the input of the outer trigger and the occurrence of light emission across discharge electrodes becomes constant in each pulse and a semiconductor substrate can be exposed to light with higher accuracy even when any components of a pulse power source are affected by a temperature change.

Abstract: A method and apparatus for driving a laser diode source, such as a laser diode or a laser diode array. The driver controlling current in response to a signal indicative of excessive current or current density. The signal may be derived from the drive current, the voltage across the laser diode source or the impedance of the laser diode source. The circuit may be pulsed using a switch, such as a GCT. The current to generate drive the laser diode source provided by a capacitive or inductive charging circuit.

Abstract: An auto laser power control circuit is provided which improves the response of the optical output level of a laser diode in accordance with variations in the operation mode. In an auto laser power control circuit for comparing a voltage corresponding to the optical output from the laser diode which emits a light in accordance with a supplied driving current with a reference voltage, and controlling the driving current so as to reduce the difference at the time of the steady operation, by controlling a switch connected between the input and output terminals of an operational unit which compares the voltage corresponding to the optical output from the laser diode and the reference voltage, the driving current to the laser diode is controlled with a smaller time constant upon the start such as a transition of from a read operation mode to a write operation mode as compared with the time of the steady operation.

Abstract: A wavelength stabilized laser module is provided which is so configured as to be simplified and smaller in size and is capable of emitting semiconductor laser light whose wavelength is stablized with high accuracy. The wavelength stablized laser module includes a semiconductor laser, a substrate, a lens to convert emitted semiconductor laser light to parallel luminous flux, a first photoelectric converter to receive a part of the parallel luminous flux and to convert it to electric signals, a filter to receive a part of the parallel luminous flux, a second photoelectric converter to receive light transmitted through the filter and to convert it to electric signals, wherein a control signal to be used for stabilization obtained by computations of electric signals fed from the converters is fed back to the semiconductor laser device and/or the substrate so that said semiconductor laser is able to stably emit laser light having a reference wavelength to be used as a target for stabilization.

Abstract: A laser driver circuit includes a pair of transistors having base electrodes respectively coupled to a differential input signal. The respective collector electrodes are coupled to a first power supply rail and the respective emitter electrodes are coupled to a laser diode via respective impedances and to respective controllable current sources to provide an average modulation voltage at the more positive of the emitter electrodes. By having the transistors in an emitter follower configuration, rather than the usual collector open collector configuration, the problem of mismatch between the output impedance of the transistors and the input impedance of the laser diode is reduced.

Abstract: A driver circuit for a laser diode or other optical source includes an input stage, an output stage, and a current generator circuit. The current generator circuit is adapted to establish a modulation current for application to one of a first output and a second output of the output stage in accordance with a differential input data signal applied to the input stage. The input stage includes first and second differential pairs. The first differential pair has the differential input data signal applied thereto, is implemented using MOS devices, and has substantially unity gain. The second differential pair receives as its inputs corresponding outputs of the first differential pair, is implemented using bipolar devices, and has a gain greater than unity.

Abstract: A device for driving a semiconductor laser in which, when a high frequency signal is superposed on a driving signal for the semiconductor laser for suppressing the scoop noise in the semiconductor laser, the amplitude of the high frequency signal can be controlled reliably and satisfactorily without dependency on temperature characteristics or chronological changes in the semiconductor laser.

Abstract: An apparatus and method for programmable control of laser diode modulation and operating point provides control for laser diodes having widely varying characteristics, such as laser diodes from a variety of manufacturers. Operating a wide variety of lasers is useful for implementation of a device independent integrated circuit for control of a laser diode. Laser diode maximum AC drive levels, AC input circuit response and DC operating point are programmed via a programmable storage coupled via control circuits to a drive amplifier and a bias circuit. The laser diode modulation control may be combined with laser diode bias control in a single integrated circuit, providing a single-chip solution for laser diode transceiver module manufacturers. The programmable storage may be one-time programmable for factory customization of laser diode transceiver module diodes, or may be an electrically alterable storage.

Abstract: An improved laser system and method of operation provides signal continuity and safety in the event of accidental interruption of the laser beam. At the transmitting end, a main laser generates a beam, which is surrounded by a low powered guard beam generated by a pulsed laser. At the receiver, a leas system includes a main lens for receiving the main laser beam and a surrounding annular segmented set of lenses acting as a set of parallel receivers for the surrounding guard beam. A trigger circuit is connected to the parallel receivers. In operation, the guard beam insulates the main laser beam and detects interruptions. When the guard beam is interrupted at any point along the length of the beam, one or more of the parallel receivers will be blocked, and a signal will be generated by the trigger circuit to activate a return laser to alter the performance of the main laser, including shutdown of the beam. Upon shutdown, the current stream of bits or packets to the main laser is buffered.

Abstract: In one embodiment of the present invention, an apparatus operates a control loop for a tunable optical device. A digital reference signal is converted to an analog reference signal and then introduced into the optical path of the tunable optical device. An analog feedback signal, corresponding to the digital reference signal, is recovered from the tunable optical device. The analog feedback signal is converted to a digital feedback signal. The apparatus sends tuning information to the tunable optical device based on analysis of the digital reference signal and the digital feedback signal. In one embodiment, the tuning information is used for wavelength locking of the tunable optical device. In another embodiment, the operation of the control loop is synchronized with another function of the tunable optical device.

Abstract: An object of the present invention is to provide a semiconductor laser device which is capable of selectively emitting two kinds of laser light of light emitting characteristics differing in wavelength, light emission point, beam shape, light emission power, longitudinal mode and so on, by switching the direction of the voltage applied to the device. There is provided the semiconductor laser device including first and second laser units, each unit having a ridge type structure and each unit comprising a multilayer structure body made of at least an n-type semiconductor layer, an active layer and a p-type semiconductor layer deposited in this order, and a p-side electrode and an n-side electrode, wherein the p-side electrode and the n-side electrode of the first laser unit and the n-side electrode and the p-side electrode of the second laser unit are electrically connected, respectively.

Abstract: A system and a method for handling laser-communication multiplexing in chaotic secure communications are disclosed. The messages to be multiplexed are encoded by chaotic laser signals of a transmitter system. The transmitted signals are then coupled to another chaotic system, the receiver system, so that the receiver and the transmitter are asymptotically synchronized. The decoding of the multiplexed messages encoded by chaotic behaviors is achieved by using a low-pass filter. This low-pass filter can effectively increase the fractal dimension of the chaotic system and enhance the periodicity of the transmitted time sequences, so that the multiplexed messages can be recovered.

Abstract: A laser transmitter is configured to use a dynamic bias signal in place of a conventional dc bias current. In particular, the envelope of the applied RF signal is detected and the envelope used to dynamically adjust the laser bias. In this manner, clipping of the laser output is avoided as the value of the RF input is changed.