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US 2003/0118283 A1Published application
Eye-safe optical fibre transmitter unit
AssigneeAgilent Technologies, Inc.
InventorDavid Healy
Life of this patent
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AssigneeAgilent Technologies, Inc.
InventorDavid Healy
Estimating the term…
The present invention relates to an eye-safe optical fibre transmitter unit (1), and to a method of producing such an unit. The unit (1) comprises a laser diode (9), an optical port (24), an optical fibre stub (18) with a fibre core (31) for carrying optical radiation (51) emitted by the laser (9) to the optical port (24). The core (31) is an index-guided core (31) surrounded by cladding (29). Focussing optics (12) focussing laser optical radiation (36) to a focus spot (50) on an entrance face (17) of the fibre stub (18) in order to increase the coupling efficiency of optical radiation (36,51) into the fibre core (31) and to decrease the coupling efficiency of optical radiation (36,52) into the surrounding cladding (29). The coupling efficiency into the core (31) is a maximum at a particular orientation of the entrance face (17) with respect to a focus axis (35) when the focus spot (50) is on the entrance face (17). However, the entrance face (17) is not oriented at this particular orientation, but is angled and/or rotated (53) away from said particular orientation in order to reduce the efficiency of coupling said optical radiation (36,51,52,) into both the fibre core (31) and cladding (29).
An optical transmitter unit (1,201), comprising a laser diode (9) for emitting optical radiation (32,36,51,251), an optical fibre stub (18) having a fibre core (31) for carrying said optical radiation (51,251) and being surrounded by a cladding (29), said optical fibre stub being disposed in a ferrule (19), and focussing optics (12) for focussing said optical radiation (36) from the laser diode (9) into an entrance face (17,40) of the fibre stub (18), characterised in that:
An optical transmitter unit (1,201), comprising a laser diode (9) for emitting optical radiation (32,36,51,251), an optical port (24) for connection to an optical fibre transmission link (23,25,28), an optical fibre stub (18) with a fibre core (31) for carrying said optical radiation (51,251) to the optical port (24), said core (31) being an index-guided core (31) surrounded by cladding (29), and focussing optics (12) for focussing said optical radiation (36) from the laser diode (9) into an entrance face (17,40) of the fibre stub (18), characterised in that:
An optical transmitter unit (1,201) as claimed in any preceding claim, in which the entrance face (17,40) is angled at a non-normal angle (47,247) to said focus axis (35).
An optical transmitter unit (1,201) as claimed in any preceding claim, in which the entrance face of the fibre stub (18) is a face (40) of a linear polarising element (39) with a polarisation axis (60) set at an angle (62) to a linear polarising direction (61) of the focussed optical radiation (36) in order to reduce the efficiency of coupling said optical radiation (36,251,252) into the fibre core (31) and cladding (29).
An optical transmitter unit (1,201) as claimed in any preceding claim, in which the optical coupling efficiency into the fibre core (31) is reduced by at least 10% from the maximum coupling efficiency at said particular orientation.
An optical transmitter unit (1,201) as claimed in any preceding claim, in which the emitted radiance from the unit (1,201) with no optical transmitter link (23,25,28) connected to the optical port (24) conforms to the US Standard CDRH Class 1 and/or the European Standard IEC 825.
An optical transmitter unit (1,201) as claimed in any preceding claim, in which the fibre stub (18) is less than 10 mm long.
An optical transmitter unit (1,201) as claimed in any preceding claim, in which the transmitter unit (1,201) includes a housing (2,7), said housing encompassing the laser diode (9), focussing optics (12) and entrance face (17,40) of the optical fibre stub (18), wherein the housing (2,7) is divided into parts by the focussing optics (12) including a first part (70) encompassing the laser diode (9) and a second part (71) encompassing the entrance face (17,40) of the optical fibre stub, wherein the division between the first part (70) and the second part (71) of the housing (2,7) helps to prevent uncoupled optical radiation (55) in the second part (71) of the housing (2,7) from reaching the first part (70) of the housing (2,7).
An optical transmitter unit as claimed in any preceding claim, in which said focus spot is a beam waist (50).
A method of assembling an optical transmitter unit (1,201), said transmitter unit comprising a laser diode (9) for emitting optical radiation (32,36,51,251), an optical port (24) for connection to an optical fibre transmission link (23,25,28), an optical fibre stub (18) with a fibre core (31) for carrying said optical radiation (51,251) to the optical port (24), said core (31) being an index-guided core (31) surrounded by cladding (29), and focussing optics (12) for focussing said optical radiation (36) from the laser diode (9) into an entrance face (17,40) of the fibre stub (18), characterised in that the method comprises the steps of:
Dependencies are inferred from the claim text.