| Patent application number | Description | Published |
|---|
| 20080292323 | SYSTEMS AND METHODS FOR REDUCING CLIPPING IN MULTICHANNEL MODULATED OPTICAL SYSTEMS - A system for reducing clipping may be used between a multichannel RF source and a laser to reduce or correct clipping that might occur in the laser as a result of negative spikes or peaks in a multichannel RF signal. The system generally includes a clipping correction circuit that receives the multichannel RF signal and responsive to the RF signal, prevents one or more of the negative peaks in the RF signal from causing clipping. The clipping correction circuit may either detect an envelope of the RF signal and/or may detect one or more peaks in the RF signal. One or more negative peaks may be prevented from causing clipping by adjusting a bias current provided by a bias control circuit and/or by modifying the RF signal with one or more clipping correction pulses coinciding with one or more negative peaks. | 11-27-2008 |
| 20080292324 | SYSTEMS AND METHODS FOR REDUCING CLIPPING IN MULTICHANNEL MODULATED OPTICAL SYSTEMS - A system for reducing clipping may be used between a multichannel RF source and a laser to reduce or correct clipping that might occur in the laser as a result of negative spikes or peaks in a multichannel RF signal. The system generally includes a clipping correction circuit that receives the multichannel RF signal and responsive to the RF signal, prevents one or more of the negative peaks in the RF signal from causing clipping. The clipping correction circuit may either detect an envelope of the RF signal and/or may detect one or more peaks in the RF signal. One or more negative peaks may be prevented from causing clipping by adjusting a bias current provided by a bias control circuit and/or by modifying the RF signal with one or more clipping correction pulses coinciding with one or more negative peaks. | 11-27-2008 |
| 20090016389 | LASER DRIVE CIRCUIT AND METHOD PROVIDING HIGH LIMIT CLIPPING CORRESPONDING TO LOW LIMIT CLIPPING IN A LASER - A laser drive circuit may be used to induce high limit clipping corresponding to natural low limit clipping in a laser, such as a laser diode, to reduce even order distortion such as composite second order (CSO) distortion. A drive current input may be provided to the active region of the laser to produce a modulated optical output in response to the drive current input. The laser drive circuit may include a current clamp at the drive current input, which clamps the drive current to provide the high limit clipping. The current clamp may receive an input current including current from a RF signal provided by a RF source together with a bias current provided by a bias current source. | 01-15-2009 |
| 20090016683 | ANGLED FIBER FERRULE HAVING OFF-AXIS FIBER THROUGH-HOLE AND METHOD OF COUPLING AN OPTICAL FIBER AT AN OFF-AXIS ANGLE - An angle-polished optical fiber may be mounted relative to a laser at an off-axis angle to allow coupled light from a laser to be substantially aligned with the axis of the fiber core. An angled fiber ferrule may facilitate providing the off-axis angle when coupling the angle-polished optical fiber to a laser package. The angled fiber ferrule includes a through hole including at least a portion that is off-axis. The axis of the off-axis portion of the through hole is angled at the off-axis angle with respect to an axis of the ferrule body portion. | 01-15-2009 |
| 20090196629 | DISTORTION COMPENSATION CIRCUIT AND METHOD BASED ON ORDERS OF TIME DEPENDENT SERIES OF DISTORTION SIGNAL - A distortion compensation circuit compensates for distortion generated by one or more non-linear elements such as a laser device. The distortion compensation circuit may be used in an optical transmitter, such as a laser transmitter used for forward path CATV applications. The distortion compensation circuit may include a primary signal path and a secondary signal path that receive an input signal. The secondary signal path produces distortion of a magnitude corresponding to the magnitude of, but at an opposite phase to, the distortion generated by the non-linear amplifier. The secondary signal path includes a plurality of distortion sub-paths with each of the distortion sub-paths configured to produce intermodulation distortion products of the same distortion order but for different frequency dependent orders in a time dependent series representative of the distortion produced by the non-linear amplifier. | 08-06-2009 |
| 20090196630 | Distortion Compensation Circuit Including One or More Phase Invertible Distortion Paths - A distortion compensation circuit compensates for distortion generated by one or more non-linear elements such as a laser device and may include a primary signal path for carrying an input signal and one or more secondary signal paths for generating distortion. The distortion compensation circuit may also include one or more controllable phase inverters on at least one of the paths. For example, the secondary signal path may include a distortion generator to produce distortion products from the input signal and a signal controlled phase inverter that inverts the phase of the distortion products. The distortion generator and phase inverter may be combined as an invertible distortion generator. The phase inversion may be controlled in response to a phase inversion control signal generated based on one or more parameters such as temperature. The secondary signal path may also include separate distortion sub-paths to produce frequency independent distortion products and frequency dependent distortion products. | 08-06-2009 |
| 20090237171 | REDUCING CROSS MODULATION IN MULTICHANNEL MODULATED OPTICAL SYSTEMS WITH ANTI-CLIPPING - A modulated optical system with anti-clipping reduces or corrects clipping that might occur in the laser as a result of negative spikes or peaks in a multichannel RF signal. The system generally detects an envelope of the RF signal to generate an anti-clipping signal that follows at least a portion of the envelope and prevents one or more negative peaks from causing clipping by adjusting a bias current in response to the anti-clipping signal. The system may also reduce cross modulation by clamping the anti-clipping signal at an anti-clipping limit during lower power periods of the RF signal. | 09-24-2009 |
| 20090278583 | CLIPPING CORRECTION SYSTEM AND METHOD FOR CORRECTING CLIPPED SIGNALS IN A RECEIVER - A system and method for restoring a clipped signal may be used in an optical receiver that detects a clipped modulated optical signal. The clipped modulated optical signal is detected to produce a clipped electrical signal including a series of clipped negative peaks and corresponding positive peaks. The clipped signal may be corrected by detecting at least one trigger peak preceding one or more clipped negative peaks to be restored and generating a replacement tip signal segment for the clipped negative peak(s) to be restored. The replacement tip signal segment may be combined with the clipped electrical signal such that the replacement tip signal segment coincides with a clipped end of the clipped negative peak to be restored to produce a restored negative peak. | 11-12-2009 |
| 20090290613 | EXTERNAL CAVITY LASER ASSEMBLY INCLUDING EXTERNAL CHIRPED EXIT REFLECTOR FOR IMPROVED LINEARITY - An external cavity laser assembly includes an external chirped exit reflector configured to reduce changes in reflectivity, thereby improving linearity. The chirped exit reflector may be configured to provide a reflectivity profile with a substantially flat peak portion, for example, as compared to the reflectivity profile of a uniform period fiber Bragg grating. The chirped exit reflector may also be configured such that an optical cavity length of the external cavity laser is shorter for higher wavelengths, thereby reducing wavelength fluctuations and changes in reflectivity caused by wavelength fluctuations. | 11-26-2009 |
| 20100086305 | REDUCING CROSS-MODULATION IN MULTICHANNEL MODULATED OPTICAL SYSTEMS - A modulated optical system with cross-modulation compensation reduces or corrects cross-modulation that might occur in a multichannel RF signal modulating a laser. The system detects the cross-modulation, for example, by detecting an envelope of the RF signal or by detecting RF power fluctuations, generates a cross-modulation detection signal, and imparts a compensating cross-modulation by adjusting a bias current of the laser in response to the cross-modulation detection signal. | 04-08-2010 |
