摘要:
A method determines power of a modulated signal that is applied to a wavelength meter by summing bin values within a designated bin range of a frequency transformed interferogram representing the modulated signal and provided by the wavelength meter. In a first embodiment of the method, the bin range within which the bin values are summed is designated by mapping a series of signal characteristics indicative of the types of the modulated signals applied to the wavelength meter, to a series of bin spans within the frequency transformed interferograms that represent the modulated signals. The method then enables a selection of a signal characteristic from the series of signal characteristics to identify the modulated signal that is applied to the wavelength meter. In response to a selection, the bin values are summed within a bin range that is consistent with the mapping of the series of signal characteristics to the series of bin spans and that is positioned about a center bin of the frequency transformed interferogram. In a second embodiment of the method, the bin range within which bin values are summed is designated automatically based on attributes of the frequency transformed interferogram.
摘要:
An interferometer system is used to detect a wavelength of an unknown signal. The interferometer system includes a fringe pattern detection system and a power detecting system. The fringe pattern detection system measures an interference fringe pattern of the unknown signal. The power detecting system measures relative power of the unknown signal before the unknown signal enters the fringe pattern detection system. The relative power of the unknown signal is used to compensate for modulation within the unknown signal.
摘要:
An optical filter for generating a filter output signal from a filter input signal, the filter output signal consisting of light from the filter input signal in a predetermined bandwidth. The filter includes a grating, a first optical assembly and an optical signal path. A portion of the input signal traverses the optical signal path such that it is diffracted from the grating to form a first intermediate beam that is input to the first optical assembly, which generates a second intermediate beam therefrom. The second intermediate beam is directed back to the grating and is diffracted by the grating, a portion of the diffracted second intermediate beam forming a portion of the filter output signal. The second intermediate beam is the inverted image of the first intermediate beam, and hence, the second reflection from the grating compensates for the time dispersion introduced by the first reflection from the grating.
摘要:
Methods and an apparatus are disclosed, wherein a print head die includes a slot and ribs across the slot. The ribs are recessed from one or both sides of the die.
摘要:
An optical noise monitor measures noise power within narrow wavelength regions between channel signals of a dense wavelength division multiplexed (DWDM) signal. The noise monitor receives the DWDM signal and cascades the signal along a multipoint travel path where the signal is incident on a series of multi-pass filters. Each multi-pass filter selects a narrow, predefined wavelength region between channel signals of the DWDM signal. Noise power within the predefined wavelength region is detected and SNR is monitored by comparing the detected noise power to the power in the channel signal. According to a first preferred embodiment of the present invention, the noise monitor includes multi-pass filters that each have reflective surfaces to guide optical energy within a predefined wavelength region through multiple passes of an optical filter. According to a second preferred embodiment of the present invention, the noise monitor includes multi-pass filters each having a serial arrangement of multiple optical filters.
摘要:
Photodetectors having low reflectivity triangular groove, surface relief gratings on homogenous material or one layer of a heterostructure. Preferably, the photodetector is a PIN photodiode in which the p-type layer is triangularly grooved. The surface relief gratings have an optical repeat distance greater than the wavelenth of light which impinges on the photodetector surface. Thus, zero order backward diffracted waves are not coupled into optical reflections which would thereby decrease the optical return loss (ORL). Furthermore, the surface relief gratings have minimum side-wall angles to limit reflection at the heterostructure interfaces from contributing to the ORL. The side-angles of the gratings are chosen to ensure that the angle of the higher order backward diffracted wave is greater than the capture angle of an optical receiver into which the photodetector is incorporated. The free-space depth of the grooves is a half-wavelength of the light impinging on the photodetector. Additionally, a novel ion milling technique is disclosed. This technique involves providing a rectangular groove grating initially etched by conventional chemical etching and photoresistive techniques and then ion milling at particular ion mill angles to obtain triangular groove surface relief gratings provided in accordance with this invention.
摘要:
A wavelength monitor detects wavelength drifts of component channel signals within multi-wavelength light signals. Multiwavelength light incident on the wavelength monitor is cascaded along a multipoint travel path. Within the travel path, the component channel signals are incident on a series of wavelength discriminators arranged on an optically transmissive member. Each wavelength discriminator is selectively transmissive to a predetermined one of the channel signals and is reflective to the remaining component channel signals of the multi-wavelength light signal. According to a first preferred embodiment of the present invention, the optical transmission through each wavelength discriminator varies monotonically according to variations in the wavelength of the predetermined channel signal. Each selectively transmitted channel signal is intercepted by a detector which produces an output current that is mapped to corresponding signal wavelengths. According to a second preferred embodiment of the present invention, the wavelength discriminator includes a dispersive element that maps the applied channel signal to spatial locations dependent upon the signal wavelength. The dispersed signal is intercepted by a split-detector responsive to the spatial location of the dispersed signal. The output currents produced by the split-detector are used to monitor wavelength deviations of the incident channel signal from the predefined channel wavelength.
摘要:
An optical cross-connect switch incorporates a pin grid actuator to selectively position optical elements relative to optical beams in the switch. A high density array of aligned, optically reflective elements is attached to the ends of independently selectable and moveable pins in the pin grid actuator. The pin grid actuator is the type extensively used in dot matrix printers. Linear motion of the pins causes the reflective element attached to the pin to intercept optical beams provided by input fibers coupled to the switch. Intercepted optical beams are redirected to designated output fibers, also coupled to the switch. A staggered arrangement of the input and output fibers equalizes all of the signal pathlengths through the switch, regardless of which pin in the pin grid actuator is selected. According to an alternate preferred embodiment of the present invention, multiple optical cross-connect switches are cascaded using a staggered arrangement of interconnecting fibers.
摘要:
The invention increases the tuning range of a laser by altering the output coupler reflectivity. In a first embodiment of the invention, the tuning range of an external cavity laser is increased by applying a substantially spectrally flat reflective coating to the front facet of a semiconductor laser which has higher reflectivity than the uncoated front facet. In addition to increasing the tuning range, the increased reflectivity of the front facet reduces the laser threshold current for all laser wavelengths. In a second embodiment of the invention, various complex coatings were applied to the output coupler to generate reflective characteristics that change according to wavelength. The complex coatings enhance reflectance at the edges of the laser tuning curve without adversely affecting the output power at the center wavelengths. This further increases the tuning range of the laser while simultaneously maintaining high output power for each selected output wavelength.
摘要:
Methods and an apparatus are disclosed, wherein a print head die includes a slot and ribs across the slot. The ribs are recessed from one or both sides of the die.