Temperature controller and light-waveguide with the same

Details Temperature controller and light-waveguide with the same Temperature controller and light-waveguide with the same

2001-09-24

2003-08-05

Jiang, Chen Wen (Department: 3744)

Refrigeration

Structural installation

With electrical component cooling

C062S003300, C324S760020, C236S00100H

Reexamination Certificate

active

06601401

ABSTRACT:

BACKGROUND OF THE INVENTION
This application claims benefit of Japanese Patent Application No. 2000-289869 filed on Sep. 25, 2000, the contents of which are incorporated by the reference.
The present invention relates to temperature controllers and light-waveguide devices using these temperature controllers. More specifically, the present invention concerns temperature controllers for temperature controlling light-waveguides or like parts as subject of temperature control requiring highly accurate temperature control as accurately as possible and light-waveguide devices with such temperature controller.
Light-waveguides provide outputs of varying wavelengths depending on the ambient temperature of their installation spots.
FIG. 7
shows a light-waveguide device
11
as an example of the light-waveguide. An input side fiber array
13
is mounted on one end of the device
11
for connecting input fibers
12
thereto. An output side fiber array
15
is mounted on the other end of the device
11
for connecting output fibers
14
thereto. The device
11
has an array
16
of a plurality of channel waveguides disposed in a fashion of being curved in a predetermined direction with different radii of curvature in its substantially central position. An input side and an output side slub waveguides
17
and
18
are connected to the incidence and emission sides, respectively, of the channel waveguide array
16
. Input and output waveguides
19
and
20
are disposed between the input side fiber array
13
and the input side slub waveguide
17
and between the output side slab waveguide
18
and the output side fiber array
15
, respectively.
In this light-waveguide device
11
, multiplexed signal light beams incident from the input waveguides
19
on the input side slab waveguide
17
are let to proceed along expandingly spaced-apart paths to be incident in in-phase relation to one another on the channel waveguide array
16
. In the channel waveguide array
16
, predetermined optical path length differences are provided along the constituent waveguides such that the optical path lengths thereof are progressively longer or shorter. Thus, light beams that are propagated through the constituent waveguides reach the output side slab waveguide
18
in phases different from one another at a predetermined interval. Actually, waveguide dispersion is present, and thus the in-phase place is tilted depending on the wavelength. As a result, the light beams are focused (or converged) in the interface between the output side slab waveguide
18
and the output waveguides
20
at different positions of the plane in dependence on the wavelengths. A given wavelength component thus can be taken out from each of the output waveguides
20
, which are disposed at positions corresponding to the wavelengths.
In this light-waveguide device
11
, variations of the temperature of the zone, in which the input side slab waveguide
17
, the channel waveguide array
16
and the output side slab waveguide
18
are disposed, result in variations of the refractive index of the quartz glass itself constituting the zone, thus varying the slab length and the optical lengths of the channel waveguides. For example, with a temperature rise, the wavelength is shifted toward the longer wavelength side, thus increasing the optical loss.
Therefore, it has been in broad practice to control the temperature to be constant by cooling the light-waveguide device with a Peltier element. In this method, the device may be connected to a temperature sensor by disposing the device on the Peltier element. In this case, a problem is posed that the temperature of the device can not be controlled uniformly if the Peltier element is smaller in size than the device.
FIG. 8
shows an example of the temperature controller, which is proposed in Japanese Laid-Open No. 9-179078 as a solution to this problem. The illustrated temperature controller has a heat conductor member
33
, which is mounted such as to commonly cover to portions of a pair of temperature control elements
31
and
32
. A light-waveguide device
35
is mounted on the heat conductor member
33
via an intervening heat conductor medium
34
such as heat conductor grease. A temperature sensor
36
is disposed in a central portion of the heat conductor member
33
intermediate between the pair temperature control elements
31
and
32
, and detects the temperature of this portion. The temperature sensor
36
outputs its temperature detection output to a temperature controller means
37
, which controls the driving of the pair temperature control elements
31
and
32
to control the detected temperature to be constant.
In this proposed temperature controller, the heat conductor medium
34
is constant temperature controlled via the heat conductor member
33
having a certain heat capacity and thus without being influenced by the ambient temperature. For the temperature detection, the temperature sensor
36
is buried in the heat conductor member
33
.
This prior art temperature controller uses two relatively small temperature control elements
31
and
32
for the temperature control of the light-waveguide
35
. For uniform temperature control of the light-waveguide
35
, the single heat conductor member
33
is interposed over the temperature control elements
31
and
32
. For uniform temperature control of the light-waveguide
35
, however, the heat conductor member
33
should have a certain great heat capacity. Therefore, a problem is posed that the temperature controller itself consumes increased power.
In the meantime, the temperature sensor
36
is buried in the heat conductor member
33
in an ordinary way such as providing a slight recess. In this case, the temperature-detecting tip of the temperature sensor
36
is enclosed in the heat conductor member
33
. Thus, compared to the case of mounting the temperature sensor
36
on the outer surface of the heat conductor member
33
, the temperature sensor
36
is less subject to the influence of the external temperature.
This temperature controller, however, has a problem that it is impossible to temperature control the light-waveguide
35
with sufficiently high accuracy even by enclosing the portion of the light-waveguide
35
with a heat-insulating member (not shown) or by enclosing the portion including the temperature control elements
31
and
32
as well as the light-waveguide
35
likewise with a heat-insulating member (not shown). The inventor of this invention confirmed that the most significant cause of this problem is that the temperature sensor
36
itself, such as thermistor, picks up the external temperature condition.
FIG. 9
expresses an example of the temperature sensor. While this example concerns a thermistor, the temperature sensor
36
has a temperature sensing portion
41
constituting its tip and a pair of leads
42
and
43
and a pair of lead lines
42
and
43
. The distal ends of the pair lead lines
42
and
43
are connected to electric wires or the like (not shown) on the side of the temperature control means
37
for the transmission of a signal representing the temperature.
In the temperature sensor
36
, the temperature sensing portion
41
at the tip is partly or fully buried in the heat conductor member
33
. In some case, end portions of the lead lines
42
and
43
are buried. Most portion of the lead lines
42
,
43
are, however, exposed to the outside of the hest conductor member
33
. These lead lines
42
and
43
thus pick up the ambient temperature condition, and change the detected temperature itself of the temperature sensing portion
41
.
To avoid this influence, it is conceivable to adopt such measure as cutting off portions of the lead lines
42
and
43
exposed to the outside of the heat conductor member
33
and connecting these portions to thicker electric wires or soldering these portions to a printed circuit board. In such case, however, the temperature of the electric wires or the soldered portions has greater influence on the temperature sensing portion
41
. Therefore,

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