Abstract: An apparatus for cavity enhanced optical detection having an improved flow cell is provided. Sensitivity of the cavity resonance condition to changes in refractive index of an analyte flowing through the flow cell is reduced. More specifically, the round trip optical path defined by the resonant cavity intersects a curved cavity input mirror at a point. This point has a location on the input mirror that is substantially independent of the refractive index of the analyte. In this manner, changes in sample refractive index do not lead to misalignment of the resonant optical cavity.

Abstract: A tunable laser and laser tuning method, based on the interaction of a spectrally dependent beam distortion and a spatial filter within a laser cavity. One embodiment of this laser is an external cavity semiconductor laser in which broad tunability is obtained by the insertion of an acousto-optic tunable filter (AOTF) into the laser cavity such that the intra-cavity laser beam passes through the AOTF in zeroth order.

Abstract: A laser tuning mechanism which embodies “spectrally dependent spatial filtering” (SDSF) and contemplates two key elements of the tuning mechanism. The first element of the SDSF tuning mechanism is a spectrally dependent beam distortion (i.e. alteration of the amplitude and/or phase profile of the beam) provided by an SDSF tuning element in a laser cavity. The second element of the SDSF tuning mechanism is an intracavity spatial filter which makes the round trip cavity loss a sensitive function of both beam distortion and cavity alignment. Such a laser can be aligned so that a specific beam distortion, which is provided by the SDSF tuning element at a tunable wavelength, is required to obtain minimum round trip cavity loss, thereby providing tunable laser emission. A preferred embodiment of the SDSF tuning mechanism is an external cavity semiconductor laser having a zeroth order acousto-optic tuning element.

Abstract: A laser tuning mechanism which embodies “spectrally dependent spatial filtering” (SDSF) and contemplates two key elements of the tuning mechanism. The first element of the SDSF tuning mechanism is a spectrally dependent beam distortion (i.e. alteration of the amplitude and/or phase profile of the beam) provided by an SDSF tuning element in a laser cavity. The second element of the SDSF tuning mechanism is an intracavity spatial filter which makes the round trip cavity loss a sensitive function of both beam distortion and cavity alignment. Such a laser can be aligned so that a specific beam distortion, which is provided by the SDSF tuning element at a tunable wavelength, is required to obtain minimum round trip cavity loss, thereby providing tunable laser emission. A preferred embodiment of the SDSF tuning mechanism is an external cavity semiconductor laser having a zeroth order acousto-optic tuning element.

Abstract: A tunable laser and laser tuning method, based on the interaction of a spectrally dependent beam distortion and a spatial filter within a laser cavity. One embodiment of this laser is an external cavity semiconductor laser in which broad tunability is obtained by the insertion of an acousto-optic tunable filter (AOTF) into the laser cavity such that the intra-cavity laser beam passes through the AOTF in zeroth order.

Abstract: An apparatus for cavity enhanced optical detection comprising: a) a source of optical radiation b) a resonant optical cavity which provides a round trip path for said optical radiation the cavity comprising: i) a plurality of mirrors, the first mirror being an input mirror which receives the optical radiation and inputs it into the cavity; ii) a flow cell positioned within said cavity, said flow cell comprising at least a first analysis channel which accommodates a flow of analyte fluid there through, iii) a second mirror, which second mirror receives the radiation from the optical source after its passage through both said input mirror and said analysis channel and reflects said received radiation.

Abstract: Methods and apparatus for decreasing the time required to calculate a ring-down time from sampled ring-down data and/or increasing the accuracy of the calculated ring-down time are provided. The time required to obtain an accurate calculation of a ring-down time is reduced by performing a linear least squares fit using an estimate B1 of the background, then using the results of the fit to estimate the error in B1. The estimated error in B1 is then used to provide an improved estimate of the ring-down time. Alternatively, the time required to accurately calculate a ring-down time is reduced by averaging consecutive data points into “bins” and performing a linear least squares fit to the resulting binned signal. The parameters obtained from the fit to the binned signal are then used to obtain an improved estimate B2 of the background, and the ring-down time is calculated by performing a linear least squares fit using B2.

Abstract: An optical fiber transmitter for emitting an information-carrying laser beam comprises an optically or electrically pumped single mode MQW (multi-quantum well) semiconductor amplifying mirror as a gain medium and a separate external reflector to form a cavity. The external cavity length defines a comb of optical modes, all or a subset of which correspond to channel wavelengths of an optical telecommunications system having plural optical channels. The semiconductor gain element has a homogeneously broadened gain region; a tuning arrangement tunes the laser from mode to mode across the gain region, thereby selecting each one of the plural optical channels. When the maximum gain bandwidth is less than mode-to-mode spacing defined by the cavity, the tuning arrangement includes a means of altering the temperature of the amplifying mirror, thereby translating the frequency of the gain peak from one mode to another.

Abstract: An optical fiber transmitter for emitting an information-carrying laser beam comprises an optically or electrically pumped single mode MQW (multi-quantum well) semiconductor amplifying mirror as a gain medium and a separate external reflector to form a cavity. The external cavity length defines a comb of optical modes, all or a subset of which correspond to channel wavelengths of an optical telecommunications system having plural optical channels. The semiconductor gain element has a homogeneously broadened gain region; a tuning arrangement tunes the laser from mode to mode across the gain region, thereby selecting each one of the plural optical channels. When the maximum gain bandwidth is less than mode-to-mode spacing defined by the cavity, the tuning arrangement includes a means of altering the temperature of the amplifying mirror, thereby translating the frequency of the gain peak from one mode to another.

Abstract: A laser tuning mechanism which embodies “spectrally dependent spatial filtering” (SDSF) and contemplates two key elements of the tuning mechanism. The first element of the SDSF tuning mechanism is a spectrally dependent beam distortion (i.e. alteration of the amplitude and/or phase profile of the beam) provided by an SDSF tuning element in a laser cavity. The second element of the SDSF tuning mechanism is an intracavity spatial filter which makes the round trip cavity loss a sensitive function of both beam distortion and cavity alignment. Such a laser can be aligned so that a specific beam distortion, which is provided by the SDSF tuning element at a tunable wavelength, is required to obtain minimum round trip cavity loss, thereby providing tunable laser emission. A preferred embodiment of the SDSF tuning mechanism is an external cavity semiconductor laser having a zeroth order acousto-optic tuning element.