Abstract: An optical device having a self-repair component capable of curing a defective component(s) is disclosed. To improve reliability as well as manufacturing yield, a photonic integrated circuit (“PIC”) for as a multi-channel optical line terminal (“OLT”) contains spare lasers or standby lasers configured to replace a failed laser(s). In one aspect, PIC includes a set of fixed-wavelength lasers (“FWLs”), a tunable-wavelength auxiliary laser (“TWAL”), a photonic detector, and a tuner. FWLs, for example, generate optical wavelengths representing optical signals. TWAL generates an optical signal with a spectrum of wavelengths based on a setting generated by the tuner. The photonic detector detects a defective wavelength. The tuner adjusts output wavelength of TWAL in response to the defective wavelength. Alternatively, PIC includes a working laser array, standby laser array, and spare laser array capable of providing two-layer laser defective protections.

Abstract: An optical device having a self-repair component capable of curing a defective component(s) is disclosed. To improve reliability as well as manufacturing yield, a photonic integrated circuit (“PIC”) for as a multi-channel optical line terminal (“OLT”) contains spare lasers or standby lasers configured to replace a failed laser(s). In one aspect, PIC includes a set of fixed-wavelength lasers (“FWLs”), a tunable-wavelength auxiliary laser (“TWAL”), a photonic detector, and a tuner. FWLs, for example, generate optical wavelengths representing optical signals. TWAL generates an optical signal with a spectrum of wavelengths based on a setting generated by the tuner. The photonic detector detects a defective wavelength. The tuner adjusts output wavelength of TWAL in response to the defective wavelength. Alternatively, PIC includes a working laser array, standby laser array, and spare laser array capable of providing two-layer laser defective protections.

Abstract: An optical device having a self-repair component capable of curing a defective component(s) is disclosed. To improve reliability as well as manufacturing yield, a photonic integrated circuit (“PIC”) for as a multi-channel optical line terminal (“OLT”) contains spare lasers or standby lasers configured to replace a failed laser(s). In one aspect, PIC includes a set of fixed-wavelength lasers (“FWLs”), a tunable-wavelength auxiliary laser (“TWAL”), a photonic detector, and a tuner. FWLs, for example, generate optical wavelengths representing optical signals. TWAL generates an optical signal with a spectrum of wavelengths based on a setting generated by the tuner. The photonic detector detects a defective wavelength. The tuner adjusts output wavelength of TWAL in response to the defective wavelength. Alternatively, PIC includes a working laser array, standby laser array, and spare laser array capable of providing two-layer laser defective protections.

Abstract: An optical device having a self-repair component capable of curing a defective component(s) is disclosed. To improve reliability as well as manufacturing yield, a photonic integrated circuit (“PIC”) for as a multi-channel optical line terminal (“OLT”) contains spare lasers or standby lasers configured to replace a failed laser(s). In one aspect, PIC includes a set of fixed-wavelength lasers (“FWLs”), a tunable-wavelength auxiliary laser (“TWAL”), a photonic detector, and a tuner. FWLs, for example, generate optical wavelengths representing optical signals. TWAL generates an optical signal with a spectrum of wavelengths based on a setting generated by the tuner. The photonic detector detects a defective wavelength. The tuner adjusts output wavelength of TWAL in response to the defective wavelength. Alternatively, PIC includes a working laser array, standby laser array, and spare laser array capable of providing two-layer laser defective protections.

Abstract: An optical device having a self-repair component capable of curing a defective component(s) is disclosed. To improve reliability as well as manufacturing yield, a photonic integrated circuit (“PIC”) for as a multi-channel optical line terminal (“OLT”) contains spare lasers or standby lasers configured to replace a failed laser(s). In one aspect, PIC includes a set of fixed-wavelength lasers (“FWLs”), a tunable-wavelength auxiliary laser (“TWAL”), a photonic detector, and a tuner. FWLs, for example, generate optical wavelengths representing optical signals. TWAL generates an optical signal with a spectrum of wavelengths based on a setting generated by the tuner. The photonic detector detects a defective wavelength. The tuner adjusts output wavelength of TWAL in response to the defective wavelength. Alternatively, PIC includes a working laser array, standby laser array, and spare laser array capable of providing two layer laser defective protections.

Abstract: An optical device having a self-repair component capable of curing a defective component(s) is disclosed. To improve reliability as well as manufacturing yield, a photonic integrated circuit (“PIC”) for as a multi-channel optical line terminal (“OLT”) contains spare lasers or standby lasers configured to replace a failed laser(s). In one aspect, PIC includes a set of fixed-wavelength lasers (“FWLs”), a tunable-wavelength auxiliary laser (“TWAL”), a photonic detector, and a tuner. FWLs, for example, generate optical wavelengths representing optical signals. TWAL generates an optical signal with a spectrum of wavelengths based on a setting generated by the tuner. The photonic detector detects a defective wavelength. The tuner adjusts output wavelength of TWAL in response to the defective wavelength. Alternatively, PIC includes a working laser array, standby laser array, and spare laser array capable of providing two layer laser defective protections.

Abstract: A heat sink includes a heat sink body having a central portion and at least a first extended portion, and heat dissipation elements extending from at least the first extended portion, the heat dissipation elements extending no further than a plane formed by an upper surface of the central portion, the central portion having a recess configured to receive a heat generating element, the central portion being free of heat dissipation elements.

Abstract: A digital activity detection circuit is provided for monitoring digital input signals such as telecommunications DS1 or DS2 signals, and for generating an alarm when a predetermined input signal loss threshold is reached, such that the input signal loss threshold does not vary with temperature, with component value or with power supply variations. Precise resolution and simplified hardware are achieved in a novel arrangement of counters in the signal activity detector to determine the resolution and signal loss threshold of the detector, all in a digital arrangement without the use of analog devices or retriggerable monostable multivibrators, and in an ASIC fabricable integrated circuit technology such as CMOS.

Abstract: A retiming circuit is provided which accurately converts half-width dual rail data with up to one unit interval of jitter with respect to the data clock, into full-width data. The circuit is comprised of D-flip-flops and associated logic elements which capture and hold a data pulse until the captured data pulse can be accurately transferred to the next circuit stage by a positive clock transition.

Abstract: A digital duplex communication system includes an echo canceller of the look-up table type. The echo canceller has a random access memory (RAM), a digital to analog converter (DAC), a subtractor, adaption means, and an address generator. The echo canceller stores echo replicas for combinations of data bits transmitted by the transmitter and subtracts these echo replicas from a received signal on line before application to the receiver. The capacity required for the RAM is reduced by storing only one echo replica for each of two complementary sets of data. To achieve this the address generator is split into a primary address generator and a complementary address generator so that complementary sets of data present the same address to the RAM. The primary address generator produces a signal to indicate which of the two complementary data sequences is being transmitted and appropriately sets the adaption means over line and a complementing circuit over line.

Abstract: A digital duplex communication system for data signals having a power-versus-frequency spectrum having two side bands located one each side of a symbol frequency, the system comprising a transmitter/receiver which includes an echo canceller. The received signal is sampled at a multiple of the bit rate and has in each symbol period a first time during which data is valid (true eye) and a second time during which data is invalid (false eye). The receiver includes circuitry to decode the data from the sampled signal during the true eye. The echo canceller is designed to be operative only during the sampling instant in the true eye and at one of the zero crossing instants in each bit period. Thus the echo canceller is operative at the instants t.sub.1 and t.sub.2 but not at the instants t.sub.3 and t.sub.4 when no information is being extracted from the received signal.