Mitsuru Kihara

Return loss characteristics of optical fiber connectors

This paper describes the return loss characteristics for four typical contact type connectors: perpendicular and oblique endface connectors employing either physical contact or contact via index matching material. The high index layer on the polished fiber endface and the index matching material, which are important connector parameters, are investigated by measuring the return loss from one perpendicular fiber endface coated with the material and by etching the fiber endface. It is useful to apply two materials with different refractive indices to derive the refractive index and thickness of high index layers on perpendicular fiber endfaces. The index matching material we use has a refractive index of 1.467 at 20/spl deg/C and a thermal coefficient of -2.9/spl times/10/sup -4///spl deg/C at 1.3 /spl mu/m. We performed return loss calculations and experiments of the four contact type connectors. The worst value at any temperature from -40 to 80/spl deg/C can be estimated, by measuring the return loss of these connectors at room temperature.

Design and performance of an angled physical contact type multifiber connector

An angled, physical contact type multifiber connector is developed on the basis of a structural design which enables direct fiber endface contact between multifiber arrays. The direct contact is achieved by utilizing the elastic nature of a ferrule material under compressive force. The fabricated connector provides a low insertion loss of 0.2 dB and a high return loss of 58.8 dB without index-matching. This connector is used in the successful development of push-on type and backpanel type 16-fiber connectors with a low insertion loss of 0.25 dB and a high return loss of 58.0 dB for future subscriber networks.

Temperature dependence of return loss for optical fiber connectors with refractive index-matching material

This letter describes the temperature dependence of return loss for optical fiber connectors with refractive index-matching material. We have performed return loss calculations and experiments for mated flat endface plugs whose fiber endfaces had a high index layer. We used index-matching material with a refractive index of 1.467 at 20/spl deg/C and a thermal coefficient of -2.9/spl times/10/sup -4///spl deg/C. We confirmed that almost all the connectors with a return loss of /spl ges/40 dB at 20/spl deg/C had return loss values of /spl ges/35 dB between -40/spl deg/C and 80/spl deg/C.<<ETX>>

Influence of Wavelength and Temperature Changes on Optical Performance of Fiber Joints With Small Gap

We have investigated the characteristics of optical fiber joints with a small gap over wide wavelength and temperature ranges. When there is a small air gap between fiber ends, the insertion loss increases between 0.0 and 0.6 dB over a wide wavelength range of 0.7-1.7 mum and a wide temperature range of -40 degC to +80 degC. The return loss varies greatly and the worst value is about 9 dB. The return loss depends on temperature with fiber end joints that employ index matching material. The value varies from more than 50 dB to a worst value of 35 dB at low temperature

Design and performance of a multifiber backpanel type connector

A compact multifiber backpanel type connector has been constructed by applying backpanel housings to multifiber push-on (MPO) type plugs. Fabricated backpanel type connectors for 8-fiber ribbons exhibit a low insertion loss of 0.2 dB and a high return loss of 60 dB.

A new type of demountable optical device for coupling single-mode planar waveguides to a multifiber array using passive alignment

A novel demountable optical device is developed for coupling single-mode waveguides to a multifiber array using passive alignment. This device is fabricated by forming V-grooves on a waveguide chip and precisely molding both end portions of the chip. The 1/spl times/8 coupling device exhibits a low insertion loss of 10.7 dB and a small loss change of /spl plusmn/0.2 dB for 100 reconnections.

Investigation Into Optical Performance of Fiber Connections With Imperfect Physical Contact

We theoretically and experimentally investigated the optical performance of fiber connections with various air-filled gaps. Such gaps might occur when a fiber connection realized using physical contact (PC) fails unexpectedly resulting in imperfect PC. The experimental results suggested that the optical performance of these fiber connections depends on both wavelength and gap width. When the air-filled gap between the fiber ends is narrow (of wavelength order) the insertion loss increases between 0.0 and 0.6 dB. The return loss varies greatly and the worst value is about 8.7 dB. When the gap is much wider than the wavelength, the insertion losses are mainly affected by the radiation loss in the air-filled gap between the fiber ends and the return losses are close to 14.7 dB, which is the Fresnel reflection value at a fiber end in air. We also found that in the worst case the insertion and return losses for fiber connections with imperfect PC can deteriorate respectively to ~ 18 and 9.4 dB at a wavelength of 1.31 μm and ~ 17 and 9.9 dB at a wavelength of 1.55 μm. In addition, we studied the characteristics of multi-connected PC-type connectors with an air-filled gap. We discovered that the total returned light from multi-connected joints with an air-filled gap could deteriorate to 5.9 dB at worst for four-connected connectors. These results support the practical use of PC-type connectors in the construction and operation of optical network systems.

Fault analysis: optical performance investigation of fiber connections with imperfect physical contact.

We investigated the insertion and return losses of optical fiber connections with various air-filled gaps. Such gaps might occur when a fiber connection using physical contact unexpectedly fails, resulting in imperfect physical contact. The optical performance of these fiber connections depends on wavelength and gap size. We revealed that the measured optical performance of fiber connections with an imperfect physical contact, i.e., with an air-filled gap, might deteriorate to ~18 dB for insertion loss and 9.4 dB for return loss at worst.

Analyzing return loss deterioration of optical fiber joints with various air-filled gaps over wide wavelength range

We experimentally investigated the return loss of optical fiber joints with various air-filled gaps. We discovered that the return loss might deteriorate to 8.6 dB for one connector and 5.9 dB for four-connected connectors at worst.

Analysis on performance deterioration of optical fiber joints with mixture of refractive index matching material and air-filled gaps

We experimentally investigated the performance of optical fiber joints with a mixture of refractive index matching material and air-filled gaps. We revealed that the insertion loss might deteriorate more than 30 dB at most.